B
Catalog of Emerging Infectious Disease Agents
The material in this appendix is provided for those who are interested in more detail on each of the agents considered by this committee to be emerging or reemerging and listed earlier in the report (see Table 2-1). It is a brief summary of information compiled from three sources, listed below, as well as additional data provided by committee and task force members, and other experts. The individual summaries are separated into three sections, corresponding to the categorizations of the earlier charts.
Benenson, Abram S. (ed.) 1990. Control of Communicable Diseases in Man, 15th edition. Washington, D.C.: American Public Health Association.
Mandell, Gerald L.; Douglas, R. Gordon, Jr.; and Bennett, John E. (eds.) 1990. Principles and Practice of Infectious Disease, 3rd edition. New York: Churchill Livingstone.
Wilson, Mary E. 1991. A World Guide to Infections: Diseases, Distribution, Diagnosis. New York: Oxford University Press.
EMERGENT BACTERIA, RICKETTSIAE, AND CHLAMYDIAE
Aeromonas
DISEASE(S) AND SYMPTOMS
Aeromonad gastroenteritis
-
acute diarrhea lasting several days, abdominal pain
-
vomiting, fever, and bloody stools may be present
Cellulitis, wound infection, and septicemia
-
septicemia occurs most often in predisposed patients
DIAGNOSIS
-
identification of the organism in patient's feces or in wound secretions
INFECTIOUS AGENT
-
Aeromonas hydrophila, A. veronii (biovariant sobria), A. caviae
-
other species of Aeromonas (A. jandaei, A. trota, A. schubertii, and A. veronii biovariant veronii) have also been associated with human disease
-
the natural habitats of Aeromonas bacteria are water and soil
MODE OF TRANSMISSION
-
ingestion of contaminated water
-
entry of organism through a break in the skin
DISTRIBUTION
-
presence of organism in clinical specimens has been documented in the Americas, Africa, Asia, Australia, and Europe
-
distribution is worldwide
INCUBATION PERIOD
-
undefined; probably 12 hours to several days
-
organism may persist for weeks to months in gastrointestinal tract
TREATMENT
-
antibiotics: trimethoprim-sulfamethoxazole, the quinolones, aminoglycosides, and tetracyclines
-
organisms tend to be resistant to penicillins and cephalosporins
PREVENTION AND CONTROL
-
proper treatment of drinking water and monitoring of well water
-
predisposed individuals should avoid aquatic environments
FACTORS FACILITATING EMERGENCE
-
predisposition (e.g., immunosuppression)
-
improved technology for detection and differentiation
-
increased awareness
Borrelia burgdorferi
DISEASE(S) AND SYMPTOMS
Lyme disease
-
distinctive skin lesion (erythema migrans) at site of tick bite that
-
appears as a red papule and expands in an annular fashion to at least 5 cm. in diameter
-
fatigue, headache, stiffness, myalgia, lymphadenopathy
-
neurologic (10 to 15% of patients) and cardiac (6 to 10% of patients) abnormalities may develop weeks to months after lesion
-
months to years after onset, swelling and pain in large joints may develop and persist for years ("Lyme arthritis")
DIAGNOSIS
-
currently based on clinical findings and serologic tests
-
tests are poorly standardized and are insensitive during the first several weeks of infection
INFECTIOUS AGENT
-
Borrelia burgdorferi, a spirochete bacterium
MODE OF TRANSMISSION
-
bite of an Ixodes tick; transmission does not occur until tick has fed for several hours
-
wild rodents (especially the white-footed mouse) and white-tailed deer maintain transmission cycle; tick depends on deer to reproduce and feeds on mice to become infected
-
no evidence for person-to-person transmission
-
transplacental transmission has been documented
DISTRIBUTION
-
in the United States: Atlantic coastal states from Maine to Georgia; upper midwestern states (concentrated in Minnesota and Wisconsin); California and Oregon
-
abroad: Europe, Canada, Japan, Australia, China, and the Commonwealth of Independent States
INCUBATION PERIOD
-
erythema migrans appears 3 to 32 days after tick exposure
TREATMENT
-
oral antibiotics (tetracycline, doxycycline, amoxicillin, erythromycin) for 10 to 30 days
-
high-dose intravenous penicillin or ceftriaxone is used if neurologic abnormalities develop
-
novel drug regimens are undergoing evaluation
PREVENTION AND CONTROL
-
avoidance of tick-infested areas; securing of clothing at entry points (ankles, cuffs, etc.); application of tick repellent to outer clothing
-
host (mice and deer) reduction
FACTORS FACILITATING EMERGENCE
-
reforestation and consequent proliferation of deer
-
housing development in wooded areas
Campylobacter jejuni
DISEASE(S) AND SYMPTOMS
Campylobacteriosis, campylobacter enteritis
-
abdominal pain, diarrhea, fever
-
illness typically lasts two to five days
-
prolonged illness and relapses may occur
-
infection is asymptomatic in many cases
DIAGNOSIS
-
detection of organism in the stool
INFECTIOUS AGENT
-
Campylobacter jejuni, a bacterium
-
other species within the genus Campylobacter have been associated with similar disease
MODE OF TRANSMISSION
-
ingestion of contaminated food, water, or milk
-
fecal-oral spread from infected person or animal
DISTRIBUTION
-
worldwide
-
organism has a vast reservoir in animals
INCUBATION PERIOD AND COMMUNICABILITY
-
incubation period is 2 to 5 days
-
disease is communicable throughout the course of infection
TREATMENT
-
rehydration and replacement of electrolytes
-
antibiotic therapy is used in some cases, though it rarely shortens duration of symptoms
PREVENTION AND CONTROL
-
chlorination of water
-
proper cooking of foods (particularly poultry) and pasteurization of milk
-
handwashing after animal contact
FACTORS FACILITATING EMERGENCE
-
improved recognition of the organism
-
an increase in poultry consumption in recent years
Chlamydia pneumoniae (TWAR Strain)
DISEASE(S) AND SYMPTOMS
TWAR infection, TWAR pneumonia
-
fever, myalgias, cough, sore throat, sinusitis
-
illness is usually mild, but recovery is slow; cough tends to last for more than two weeks
DIAGNOSIS
-
isolation of organism from throat or sputum
INFECTIOUS AGENT
-
Chlamydia pneumoniae (TWAR), a chlamydia
-
strain name is derived from designation of first two isolates, TW-183 from Taiwan and AR-39 (acute respiratory)
MODE OF TRANSMISSION
-
person to person; thought to be acquired by inhalation of infective organisms
-
possibly by direct contact with secretions of an infected person
DISTRIBUTION
-
probably worldwide
-
the majority of cases have occurred in North America, Asia, and Europe
INCUBATION PERIOD AND COMMUNICABILITY
-
1 to 4 weeks
-
period of communicability is unknown but presumed to be long, based on duration of documented outbreaks
TREATMENT
-
antibiotics: tetracycline or erythromycin
PREVENTION AND CONTROL
-
avoidance of overcrowding in living and sleeping quarters
FACTORS FACILITATING EMERGENCE
-
increased recognition
Chlamydia trachomatis
DISEASE(S) AND SYMPTOMS
Genital chlamydia
-
urethritis in males, mucopurulent cervicitis in females (opaque discharge, itching, burning upon urination)
-
asymptomatic infection can occur
-
in women, infertility and ectopic pregnancy can result from chronic infection
DIAGNOSIS
-
identification of organism on intraurethral or endocervical swab material
INFECTIOUS AGENT
-
Chlamydia trachomatis, a bacterium
MODE OF TRANSMISSION
-
sexual intercourse
DISTRIBUTION
-
worldwide; recognition has increased in the United States, Canada, Europe, and Australia over the past two decades
INCUBATION PERIOD AND COMMUNICABILITY
-
incubation period is poorly defined, probably 7 to 14 days or longer
-
period of communicability is unknown
TREATMENT
-
oral antibiotics: tetracycline, doxycycline, or quinolone
PREVENTION AND CONTROL
-
condom use during sexual intercourse
-
prophylactic treatment of sexual partners
FACTORS FACILITATING EMERGENCE
-
probably increased sexual activity
Clostridium difficile
DISEASE(S) AND SYMPTOMS
Clostridium difficile colitis
-
antibiotic-associated colitis
-
pseudomembranous colitis
-
watery diarrhea, bloody diarrhea, abdominal pain
DIAGNOSIS
-
detection of C. difficile toxin in the stool
-
visualization of characteristic pseudomembranes during endoscopy of colon
INFECTIOUS AGENT
-
Clostridium difficile, a toxin-producing bacterium
MODE OF TRANSMISSION
-
fecal-oral transmission
-
acquisition of organism from the environment
DISTRIBUTION
-
worldwide
-
an estimated 3 percent of healthy adults carry the organism in the gut
INCUBATION PERIOD AND COMMUNICABILITY
-
colitis typically begins during, or shortly after, antibiotic administration (changes in gastrointestinal tract flora due to antibiotic use allow proliferation of the organism and its production of toxins)
TREATMENT
-
discontinuation of aggravating antibiotic treatment if possible
-
antibacterial agents: metronidazole, vancomycin, bacitracin
PREVENTION AND CONTROL
-
avoidance of unnecessary antibiotic administration
FACTORS FACILITATING EMERGENCE
-
immunosuppression
-
increased recognition
Ehrlichia chaffeensis
DISEASE(S) AND SYMPTOMS
Ehrlichiosis
-
fever, malaise, headache, lymphadenopathy, anorexia
-
fever usually lasts 2 weeks
-
meningitis is occasionally reported
DIAGNOSIS
-
poor; few laboratories have antigen for immunoflourescence serology by surrogate E. canis antigen
INFECTIOUS AGENT
-
Ehrlichia chaffeensis, a rickettsia
-
reservoir is unknown
MODE OF TRANSMISSION
-
an undetermined tick transmits the agent (possibly the widely distributed species, Amblyomma americanum)
-
no evidence of person-to-person transmission
-
although other types of Ehrlichia are transmitted to dogs by the brown dog tick, dogs have not been found to be reservoirs of human disease
DISTRIBUTION
-
Southern and mid-Atlantic United States
INCUBATION PERIOD
-
unknown; possibly 1 to 3 weeks
TREATMENT
-
oral antibiotics: tetracycline
PREVENTION AND CONTROL
-
avoidance of tick-infested areas; securing of clothing at entry points (ankles, cuffs, etc.); application of tick repellent to outer clothing
FACTORS FACILITATING EMERGENCE
-
organism is probably newly recognized
-
possible increase in reservoir and vector populations
Escherichia coli O157:H7
DISEASE(S) AND SYMPTOMS
-
Hemorrhagic colitis; hemolytic uremic syndrome
DIAGNOSIS
-
identification of antibodies to O157:H7 serotype
INFECTIOUS AGENT
-
Escherichia coli O157:H7, a bacterium
-
one of several ''EHEC" (enterohemorrhagic E. coli) strains
-
EHEC bacteria produce potent cytotoxins, called Shiga-like toxins 1 and 2
-
cattle are believed to be the reservoirs of EHECs
MODE OF TRANSMISSION
-
ingestion of contaminated food, typically poorly cooked beef and raw milk
-
transmission by direct contact may occur in high-risk populations
DISTRIBUTION
-
probably worldwide
-
most cases have occurred in North America and Europe
INCUBATION PERIOD
-
12 to 60 hours
TREATMENT
-
oral replacement of fluids and electrolytes (intravenous if necessary)
PREVENTION AND CONTROL
-
proper cooking of meat
-
hand washing
-
proper sewage and water treatment
FACTORS FACILITATING EMERGENCE
-
probably spread of a bacterial virus carrying the gene for Shiga-like toxin production into the otherwise unremarkable host, E. coli O157:H7
Haemophilus influenzae biogroup aegyptius
DISEASE(S) AND SYMPTOMS
Brazilian purpuric fever
-
irritation of the conjunctivae of the eyes, followed by edema of the eyelids, photophobia, and mucopurulent discharge
-
high fever appears 3 to 15 days after conjunctivitis, along with vomiting and purpura
-
case fatality rate is 70 percent, with death occurring shortly after onset of systemic symptoms
-
disease was first recognized in 1984
DIAGNOSIS
-
microscopic examination of bacterial culture of conjunctival discharge
-
detection of organism in the blood
INFECTIOUS AGENT
-
Haemophilus influenzae biogroup aegyptius, a bacterium
MODE OF TRANSMISSION
-
contact with the conjunctival or respiratory discharges of infected persons
-
eye flies are suspected mechanical vectors
DISTRIBUTION
-
nearly all reported cases of Brazilian purpuric fever have occurred in southern Brazil (most cases have been in young children)
-
one case was reported from Australia
INCUBATION PERIOD AND COMMUNICABILITY
-
incubation period is unknown
-
disease is communicable for the duration of active infection
TREATMENT
-
high-dose intravenous antibiotics: ampicillin, chloramphenicol
PREVENTION AND CONTROL
-
prompt treatment of patients and close contacts
-
avoidance of exposure to eye flies
-
possibly vector control
FACTORS FACILITATING EMERGENCE
-
possibly an increase in bacterial virulence due to mutation
Helicobacter pylori
DISEASE(S) AND SYMPTOMS
-
dyspepsia, abdominal pain
-
chronic infection may result in peptic ulcer, gastric cancer
DIAGNOSIS
-
detection of antibodies in blood by ELISA
-
biopsy and culture
INFECTIOUS AGENT
-
Helicobacter pylori, a bacterium (formerly known as Campylobacter pylori)
MODE OF TRANSMISSION
-
unknown; some studies suggest a zoonotic origin
DISTRIBUTION
-
worldwide
INCUBATION PERIOD AND COMMUNICABILITY
-
unknown
TREATMENT
-
antibiotics: metronidazole, ampicillin, tetracycline
-
bismuth
PREVENTION AND CONTROL
-
none
FACTORS FACILITATING EMERGENCE
-
increased recognition
Legionella pneumophila
DISEASE(S) AND SYMPTOMS
Legionnaires' disease, Pontiac fever
-
initial symptoms include malaise, headache, myalgias, fever, chills, and cough
-
fever rises rapidly within 1 day, and may precede the development of pulmonary symptoms
-
changes in mental status occur in 25 to 75 percent of patients
-
complications include renal failure, lung abscesses, and extrapulmonary infection
-
Pontiac fever may represent a reaction to inhaled antigen rather than bacterial invasion; patients recover in 2 to 5 days without treatment
DIAGNOSIS
-
isolation of the organism on special media
-
demonstration of organism by direct immunofluorescence stain of involved tissue or respiratory secretions
INFECTIOUS AGENT
-
Legionella pneumophila, a bacterium
MODE OF TRANSMISSION
-
aerosol transmission via aerosol-producing devices (especially air cooling systems)
-
person-to-person transmission has not been documented
DISTRIBUTION
-
documented as an important cause of pneumonia in North America, Europe, Asia, and Australia
-
also identified in South America and Africa
INCUBATION PERIOD
-
2 to 10 days for Legionnaires' disease
-
5 to 66 hours for Pontiac fever
TREATMENT
-
for Legionnaires' disease, antibiotics: erythromycin and rifampin
PREVENTION AND CONTROL
-
drainage of cooling towers when not in use
-
hyperchlorination and elevation of hot water temperature have been partially successful in interrupting waterborne outbreaks
FACTORS FACILITATING EMERGENCE
-
recognition in an epidemic situation
Listeria monocytogenes
DISEASE(S) AND SYMPTOMS
Listeriosis
-
typically manifested as meningoencephalitis and/or septicemia (preceded by fever, headache, and vomiting)
-
delirium, shock, and coma may occur
-
disease is particularly dangerous to pregnant women, whose infants may be stillborn if infected
-
immunosuppressive conditions facilitate infection
-
fetuses and newborn infants are especially susceptible to infection
DIAGNOSIS
-
isolation of organism from the blood or cerebrospinal fluid
INFECTIOUS AGENT
-
Listeria monocytogenes, a bacterium
MODE OF TRANSMISSION
-
ingestion of contaminated foods (particularly nonreheated hotdogs, undercooked chicken, various soft cheeses, and food purchased from store delicatessen counters1)
-
direct contact with organism or with soil contaminated with infected animal feces
-
transmission can also occur by inhalation of the organism
DISTRIBUTION
-
worldwide
INCUBATION PERIOD AND COMMUNICABILITY
-
incubation period is extremely variable (from 3 to 70 days)
-
disease is communicable for duration of infection
TREATMENT
-
antibiotics: penicillin, ampicillin, contrimoxazole
PREVENTION AND CONTROL
-
for pregnant women, avoidance of certain foods (see above) is recommended
-
proper food-handling practices
-
pasteurization of dairy products
FACTORS FACILITATING EMERGENCE
-
increased awareness, recognition, and reporting
Mycobacterium tuberculosis
DISEASE(S) AND SYMPTOMS
Tuberculosis
-
cough, weight loss, night sweats, and low-grade fever
-
hemoptysis and chest pain are common
-
extrapulmonary tuberculosis can cause symptoms involving any organ system including kidneys, liver, and central nervous system
DIAGNOSIS
-
identification of tubercle bacteria in patient's sputum
-
characteristic changes visible in chest x-ray
INFECTIOUS AGENT
-
Mycobacterium tuberculosis, a mycobacterium
MODE OF TRANSMISSION
-
inhalation of droplet nuclei containing the bacteria (droplet nuclei can remain suspended in the air for up to 2 hours)
DISTRIBUTION
-
worldwide
-
annually, 8 million people develop clinical tuberculosis and 3 million people die of tuberculosis
-
it is estimated that up to 50 percent of the world's population (2 billion people) are infected, clinically or subclinically, with tuberculosis
INCUBATION PERIOD AND COMMUNICABILITY
-
4 to 12 weeks
-
disease is communicable as long as viable bacteria remain in the sputum
TREATMENT
-
chemotherapy involving a combination of antibiotics (esp. isoniazid and rifampin) for a period of 6 to 12 months
PREVENTION AND CONTROL
-
treatment of patients with active infection to prevent spread
-
strict respiratory isolation for patients with active pulmonary infection
-
preventive antibiotic treatment of contacts
FACTORS FACILITATING EMERGENCE
-
an increase in immunosuppressed populations
Staphylococcus aureus (and Toxic Shock Syndrome)
Toxic shock syndrome
-
although symptoms of infection with S. aureaus can range from a single pustule to septicemia to death, "toxic shock syndrome," a newly emerged disease caused by S. aureus is the focus of this summary
-
symptoms of toxic shock syndrome (TSS) include sudden onset of high fever, vomiting, profuse diarrhea, myalgia, hypotension, and, in severe cases, shock
-
a sunburn-like rash is present in the acute phase of the disease, often accompanied by desquamation of the plams and soles
-
disorientation and alterations in consciousness may be present
DIAGNOSIS
-
isolation of the bacteria from the vagina or from abscess
INFECTIOUS AGENT
-
Staphylococcus aureus, a bacterium
MODE OF TRANSMISSION
-
TSS has been associated with use of super-absorbent tampons, prolonged use of diaphragms, and cesarean section deliveries
-
reported cases of TSS in males have been linked to local S. aureus infections such as abscesses and postsurgical infections
-
not directly transmitted from person to person
DISTRIBUTION
-
sporadic cases throughout the world
-
TSS epidemic in the United States occurred 1980-1981
INCUBATION PERIOD
-
unknown
TREATMENT
-
initial treatment involves replacement of lost fluids/electrolytes
-
intravenous antibiotics
PREVENTION AND CONTROL
-
avoidance/minimal use of highly absorbent tampons
-
a better understanding of factors associated with nonmenstrual cases is needed
FACTORS FACILITATING EMERGENCE
-
use of super-absorbent tampons
Streptococcus pyogenes (Group A)
DISEASE(S) AND SYMPTOMS
-
the most common conditions caused by group A streptococcal bacteria are sore throat and skin infection
-
other conditions caused by the bacteria include scarlet fever, rheumatic fever, puerperal fever, septicemia, wound infections, and pneumonia
-
rarely, group A bacteria cause sepsis and streptococcal toxic shock syndrome (which can be fatal)
DIAGNOSIS
-
identification of group A streptococcal antigen in pharyngeal secretions
INFECTIOUS AGENT
-
Streptococcus pyogenes (group A), a bacterium
MODE OF TRANSMISSION
-
direct or intimate contact with infected persons/carriers of the organism
-
outbreaks of streptococcal sore throat have been linked to contaminated food
DISTRIBUTION
worldwide
INCUBATION PERIOD AND COMMUNICABILITY
1 to 3 days
with antibiotic therapy, period of communicability is as short as 1 to 2 days
untreated cases, especially those involving purulent discharges, can be communicable for weeks to months
TREATMENT
antibiotics: penicillin
PREVENTION AND CONTROL
in some cases, prophylactic treatment of close contacts with penicillin
people with respiratory infections or skin infections should not directly handle food
FACTORS FACILITATING EMERGENCE
probably a change in the virulence of some streptococci in this group has been responsible for deadly infections
Vibrio cholerae
DISEASE(S) AND SYMPTOMS
Cholera
sudden onset of profuse, watery diarrhea followed by profound dehydration
can progress to shock within 4 to 12 hours
in severe untreated cases, death can occur within hours
DIAGNOSIS
isolation of organism from stool or rectal swab
INFECTIOUS AGENT
Vibrio cholerae serogroup O1, biotypes cholerae and El Tor (bacteria)
MODE OF TRANSMISSION
ingestion of water contaminated with the feces of infected persons (organism is easily killed with chlorination but can survive in ice cubes, salt water, and mineral water)
ingestion of food washed with contaminated water
DISTRIBUTION
-
epidemics are sporadic, the most recent being in South America in 1991
-
disease is endemic in southern Asia
INCUBATION PERIOD AND COMMUNICABILITY
-
from a few hours to 5 days; usually 2 to 3 days
-
direct, person-to-person transmission is of minor importance in areas with good sanitary facilities
TREATMENT
-
replacement of fluids and electrolytes (oral rehydration therapy [ORT])
-
antibiotics eradicate organisms and shorten duration of illness, but are secondary in importance to rehydration
PREVENTION AND CONTROL
-
currently available vaccine provides only partial protection (50%) of short duration (3 to 6 months) and thus is of no practical value in epidemic control
-
avoidance of contaminated food and water, as well as raw and undercooked crabs and shellfish harvested from potentially contaminated water
FACTORS FACILITATING EMERGENCE
-
breakdown of sanitation measures protecting water supplies
-
in Peru, miscalculation of risks involved in chlorine use (and consequent lack of chlorine use)
Vibrio vulnificus
DISEASE(S) AND SYMPTOMS
-
varies from cellulitis to fatal bacteremia associated with chronic cutaneous ulcers
-
soft tissue infection and septicemia can occur if organism enters body percutaneously
-
organism has occasionally been associated with diarrheal illness
DIAGNOSIS
-
isolation of the organism from blood or cutaneous lesions in bacteremic cases
INFECTIOUS AGENT
-
Vibrio vulnificus, a bacterium
MODE OF TRANSMISSION
-
contact of superficial wounds with seawater or seafood containing the organism
-
ingestion of contaminated water or food (usually raw or undercooked seafood) by immunocompromised persons, especially those with hepatic cirrhosis
-
not transmitted person to person
DISTRIBUTION
-
organism is most commonly found in the Gulf states of the United States and is probably part of the normal marine flora in warmer climates
INCUBATION PERIOD
-
incubation period is 10 to 20 hours
TREATMENT
-
antibiotic therapy
-
surgical drainage may be necessary with soft tissue infections
-
supportive treatment for diarrheal illness (e.g., oral fluid replacement)
PREVENTION AND CONTROL
-
avoidance of exposure of open skin wounds to seawater
-
careful handling of raw or undercooked seafood by persons with superficial wounds
-
avoidance of raw or undercooked seafood, particularly by immunocompromised persons
FACTORS FACILITATING EMERGENCE
-
increased recognition
EMERGENT VIRUSESBovine Spongiform Encephalopathy Agent
DISEASE(S) AND SYMPTOMS
Bovine spongiform encephalopathy (BSE) in cattle
-
progressive neurological disease, staggering
-
BSE agent has not caused any cases of human disease
DIAGNOSIS
-
histology of brain tissue
-
epidemiological characteristics
-
no serological tests are currently available
INFECTIOUS AGENT
-
BSE agent, a virus-like agent similar to scrapie prion in sheep
MODE OF TRANSMISSION
-
probably ingestion by cattle of poorly disinfected sheep offal
DISTRIBUTION
-
epidemic in England in 1990; cases in France and Switzerland
INCUBATION PERIOD AND COMMUNICABILITY
-
unknown
TREATMENT
-
none
PREVENTION AND CONTROL
-
destruction of infected animals to prevent spread
-
control measures instituted during 1990 epidemic: restrictions on use of cattle serum and cells for pharmaceutical (including vaccines) manufacturing in Europe
-
changes in the rendering process (a return to batch processing and solvent use) will probably provide effective control
FACTORS FACILITATING EMERGENCE
-
changes in the rendering process: continuous processing and elimination of solvents
California Serogroup Viruses (LaCrosse, Jamestown Canyon, California Encephalitis)
DISEASE(S) AND SYMPTOMS
-
acute, inflammatory viral diseases of short duration involving parts of the brain, spinal cord, and meninges
-
many infections are asymptomatic; severe infections involve acute onset, headache, high fever, stupor, disorientation, tremors, spasticity, and coma
-
case fatality rate is 0.5 percent
DIAGNOSIS
-
demonstration of antibodies in blood or cerebrospinal fluid
INFECTIOUS AGENT
-
California serogroup viruses: LaCrosse, Jamestown Canyon, California encephalitis, and snowshoe hare virus
MODE OF TRANSMISSION
-
bite of an infective mosquito
-
not directly transmitted from person to person
DISTRIBUTION
-
United States, Canada, and Commonwealth of Independent States
-
cases typically occur in temperate latitudes in summer and early fall
INCUBATION PERIOD
-
usually 5 to 15 days
TREATMENT
-
supportive only
PREVENTION AND CONTROL
-
avoidance of exposure to mosquitoes during hours of biting (dusk to dawn)
-
mosquito control (elimination of breeding sites)
FACTORS FACILITATING EMERGENCE
-
reforestation
-
poor vector control
-
increasing interface between human activity and endemic areas
-
discarded tires as a source of mosquito breeding sites
Chikungunya Virus
DISEASE(S) AND SYMPTOMS
Chikungunya fever
-
abrupt onset of fever, headache, myalgias
-
joint pain, arthritis, hemorrhagic fever
-
disease is usually acute and self-limited
-
isolation of the virus from patient's blood
INFECTIOUS AGENT
-
Chikungunya virus, a single-stranded RNA virus
MODE OF TRANSMISSION
-
bite of an infective Aedes mosquito
-
not directly transmitted from person to person
DISTRIBUTION
-
primarily Africa, South Asia, and the Philippines
INCUBATION PERIOD
-
3 to 12 days
TREATMENT
-
supportive only
PREVENTION AND CONTROL
-
mosquito control in endemic areas
-
a live, attenuated vaccine is being tested
FACTORS FACILITATING EMERGENCE
-
unknown
Crimean-Congo Hemorrhagic Fever Virus
DISEASE(S) AND SYMPTOMS
Crimean-Congo hemorrhagic fever
-
abrupt onset of fever, headache, chills, photophobia, myalgia, and abdominal pain
-
nausea, vomiting, and diarrhea may be present; rash is common
-
infection to death ratio is estimated at 25:1
-
in pregnant women, infection is severe and often results in death
DIAGNOSIS
-
isolation of the virus from cerebrospinal fluid, blood, or other tissues
INFECTIOUS AGENT
-
Crimean-Congo virus, an RNA virus
MODE OF TRANSMISSION
-
bite of an infective tick
-
contact with blood or secretions/excretions of an infected person or animal
-
virus has also spread by aerosolization
DISTRIBUTION
-
Eastern Europe, central and western Asia, Middle East, Sub-Saharan and southern Africa
INCUBATION PERIOD AND COMMUNICABILITY
-
3 to 6 days
-
blood of an infected person has high concentration of virus for 8 to 10 days
TREATMENT
-
supportive
-
ribavirin may be helpful
PREVENTION AND CONTROL
-
strict isolation of infected patients
-
avoidance of contact with ticks and infected persons and animals
-
in the Commonwealth of Independent States, a killed vaccine is used in high-risk populations, with uncertain efficacy
FACTORS FACILITATING EMERGENCE
-
lack of effective tick control
-
lack of effective animal quarantine
Dengue Virus
Dengue/dengue hemorrhagic fever (DHF)/dengue shock syndrome (DSS)
-
sudden onset of fever, headache, joint and muscle pain
-
nausea, vomiting, abdominal pain, and rash may be present
-
fever typically lasts 3 to 7 days; convalescence may be prolonged
-
initial phase of DHF/DSS may be similar to the above, but is followed by hemorrhagic phenomena, bleeding from multiple sites, and vascular collapse
DIAGNOSIS
-
isolation of virus from blood
-
serologic studies (ELISA, etc.)
INFECTIOUS AGENT
-
dengue viruses, serotypes 1-4 (all four types can cause dengue hemorrhagic fever)
MODE OF TRANSMISSION
-
bite of an infective Aedes aegypti or Aedes albopictus mosquito
-
not directly transmitted from person to person
Distribution
-
epidemic and endemic in tropical and subtropical areas of Africa, the Americas, Asia, Oceania, and Australia
-
widespread in the Caribbean basin
INCUBATION PERIOD AND COMMUNICABILITY
-
3 to 14 days, average 7 to 10 days
-
while disease is not transmitted from person to person, patients can be infective for mosquitoes from the day before to the end of the febrile period (5 to 7 days)
TREATMENT
-
supportive only
PREVENTION AND CONTROL
-
control of mosquitoes
-
vaccine is not yet available
FACTORS FACILITATING EMERGENCE
-
lack of effective mosquito control
-
increased urbanization in the tropics
-
increased air travel
Filoviruses (Marburg, Ebola)
DISEASE(S) AND SYMPTOMS
-
sudden onset of fever, headache, joint and muscle pain, followed by sore throat, diarrhea, abdominal pain, vomiting, and rash
-
after 3 to 5 days of fever, hemorrhagic manifestations begin
-
case fatality rate for Marburg virus infection is 25 percent
-
case fatality rates for Ebola infection have ranged from 50 to 90 percent
DIAGNOSIS
-
isolation of virus from blood, other tissues, or body fluids
-
serological detection of antibodies
INFECTIOUS AGENT
-
Ebola virus
-
Marburg virus
MODE OF TRANSMISSION
-
close contact with infected persons or infected blood, tissues, secretions, or excretions
-
transplacental and venereal transmission have occurred
-
possibly contact with infected animal vectors (primates)
DISTRIBUTION
-
Ebola: epidemics have taken place in Sudan and Zaire; virus may be endemic in other parts of Africa; monkeys infected with an Ebola-like virus were imported to the United States from the Philippines in 1989 (no human illness resulted)
-
Marburg: scattered human cases have occurred in central, eastern, and southern Africa; cases reported in Germany were a result of handling material from infected African green monkeys imported from Uganda
INCUBATION PERIOD AND COMMUNICABILITY
-
for both virus infections, 5 to 10 days
-
both viruses can persist in humans for at least 2 months
TREATMENT
-
supportive only
PREVENTION AND CONTROL
-
avoidance of contact with infected persons and their blood, other tissues, and body fluids
-
strict isolation of infected persons
FACTORS FACILITATING EMERGENCE
-
virus-infected monkeys shipped from developing countries via air
Hantaviruses (Hantaan, Puumala, and Seoul)
DISEASE(S) AND SYMPTOMS
Hemorrhagic fever with renal syndrome
-
abrupt onset of fever, headache, and myalgias; abdominal pain, vomiting, and diarrhea
-
the appearance of petechiae (reddish purple, blood-filled spots) on the palate
-
in the severe form of the disease, initial febrile period may be followed by hypotension and hemorrhage from multiple sites
-
most survivors regain normal renal function
-
the most severe disease is caused by the Hantaan virus
DIAGNOSIS
-
demonstration of specific antibodies using IFA or ELISA
INFECTIOUS AGENT
-
hantaviruses, a group of RNA viruses
-
several different subtypes exist, each associated with a single rodent reservoir species (Hantaan—Apodemus field mouse; Puumala—Clethrionomys bank vole; Seoul—rats)
MODE OF TRANSMISSION
-
contact with infective material (feces, urine, saliva, tissue, etc.) of rodents
-
contact is usually by aerosol
-
transplacental transmission has been documented; other person-to-person spread has not been reported
DISTRIBUTION
-
hantaviruses are found on all continents
-
endemic and epidemic disease in China, Korea, and the Commonwealth of Independent States
-
Hantaan virus is widely distributed in eastern Asia
-
Puumala virus is common to Scandinavia and western Europe
INCUBATION PERIOD
-
4 to 42 days; average is 12 to 16 days
TREATMENT
-
supportive only
-
recent studies show that ribavirin may shorten illness and reduce mortality
PREVENTION AND CONTROL
-
rodent control
FACTORS FACILITATING EMERGENCE
-
human invasion of virus ecologic niche
Hepatitis B Virus
DISEASE(S) AND SYMPTOMS
Hepatitis B
-
insidious onset of anorexia, abdominal pain
-
sometimes arthralgias and rash, often progressing to jaundice
-
chronic infection leads to cirrhosis of the liver
DIAGNOSIS
-
elevated levels of certain liver enzymes
-
serological antibody tests (RIA, ELISA)
INFECTIOUS AGENT
-
Hepatitis B virus, a double-stranded DNA virus
MODE OF TRANSMISSION
-
virus enters body through a break in the skin or through mucous membranes
-
transmission via contaminated needles, transfusions of blood or blood products, sexual contact
-
transplacental transmission
DISTRIBUTION
-
worldwide
INCUBATION PERIOD AND COMMUNICABILITY
-
45 to 180 days, average 60 to 90 days
-
blood containing the virus has been shown to be infective many weeks before the onset of first symptoms and to remain infective during the acute clinical course of the disease
-
chronic carriers are infectious
TREATMENT
-
supportive only
PREVENTION AND CONTROL
-
immunization with Hepatitis B vaccine
-
testing of donor blood
FACTORS FACILITATING EMERGENCE
-
possibly increased sexual activity and intravenous drug abuse
Hepatitis C Virus
DISEASE(S) AND SYMPTOMS
Classic non-A, non-B hepatitis
-
onset is insidious and accompanied by anorexia, nausea, vomiting, and jaundice
-
course is similar to hepatitis B, but more prolonged
-
strong tendency to progress to chronic hepatitis and liver disease, which can be asymptomatic
-
the most common form of posttransfusion hepatitis
DIAGNOSIS
-
diagnosed by exclusion of hepatitis A, B, and delta viruses and other causes of liver injury
-
blood tests are now available for clinical use
INFECTIOUS AGENT
-
exact viral agent is unknown
-
agent appears to be a flavivirus
MODE OF TRANSMISSION
-
percutaneous exposure to contaminated blood and plasma derivatives
-
the role of sexual activity in transmission is not well defined
DISTRIBUTION
-
worldwide
-
common among dialysis patients, hemophiliacs, health care workers, and drug addicts
INCUBATION PERIOD AND COMMUNICABILITY
-
20 to 90 days (mean: 50)
-
period of communicability extends from one week after exposure into chronic stage
TREATMENT
-
existing antivirals have little effect
-
interferon may be helpful to chronic carriers
PREVENTION AND CONTROL
-
no vaccine is available
-
monitoring of blood supply for anti-HCV and elevated liver enzyme levels
-
pasteurization of clotting factor concentrates
FACTORS FACILITATING EMERGENCE
-
application of molecular virology techniques to identify etiologic agent
-
an old disease syndrome newly documented
Hepatitis E Agent
DISEASE(S) AND SYMPTOMS
Hepatitis E
-
also known as epidemic non-A, non-B hepatitis; waterborne non-A, non-B hepatitis; enterically transmitted non-A, non-B hepatitis
-
sudden onset of fever, malaise, nausea, and anorexia
-
disease varies in severity from a mild illness lasting 7 to 14 days, to a severely disabling disease lasting several months (rare)
-
jaundice can be present
-
no evidence of a chronic form
DIAGNOSIS
-
liver function tests
-
exclusion of other etiologies of hepatitis (especially hepatitis A) by serologic tests
INFECTIOUS AGENT
-
virus is not yet fully characterized
-
virus-like particles have been detected in the feces of infected patients
MODE OF TRANSMISSION
-
ingestion of contaminated water (most outbreaks have been linked to fecal contamination of water)
-
fecal-oral transmission
DISTRIBUTION
-
may be widespread
-
majority of outbreaks have been reported from Asia, Africa, the Commonwealth of Independent States, and Mexico
INCUBATION PERIOD AND COMMUNICABILITY
-
30 to 40 days
-
period of communicability is unknown; may be similar to hepatitis A
TREATMENT
-
supportive only
PREVENTION AND CONTROL
-
educational programs stressing importance of sanitary disposal of feces, careful hand washing after defecation and before handling food
FACTORS FACILITATING EMERGENCE
-
agent and disease are newly recognized
Human Herpesvirus-6
DISEASE(S) AND SYMPTOMS
-
sudden onset of fever (fever lasts 3 to 5 days)
-
maculopapular rash (exanthem subitum/roseola infantum) that appears on the trunk and spreads to rest of body
-
febrile seizures have been reported in very few cases
DIAGNOSIS
-
serology
-
ELISA is now available experimentally
INFECTIOUS AGENT
-
Human herpesvirus-6
MODE OF TRANSMISSION
-
unknown
DISTRIBUTION
-
appears ubiquitous in United States and Japan (antibody prevalence as high as 90 percent)
-
disease usually occurs in children under 4 years of age
-
incidence is highest in the spring
INCUBATION PERIOD AND COMMUNICABILITY
-
incubation period is 10 days
TREATMENT
-
supportive only
PREVENTION AND CONTROL
-
none
FACTORS FACILITATING EMERGENCE
-
newly recognized
Human Immunodeficiency Virus (HIV), Types 1 and 2
DISEASE(S) AND SYMPTOMS
HIV disease; acquired immunodeficiency syndrome (AIDS); AIDS-related complex (ARC)
-
clinical features of infection are correlated with degree of immune dysfunction and range from asymptomatic to progressive and lethal
-
manifestations can involve any organ system of the body
-
initially: fever, weight loss, diarrhea, fatigue, cough, lymphadenopathy, oral thrush, and skin lesions (AIDS-related complex)
-
several opportunistic infections and cancers are very common and are considered specific indicators of HIV infection, including tuberculosis and other mycobacterial infections; Pneumocystis carinii pneumonia; chronic cryptosporidiosis; toxoplasmosis of the central nervous system (CNS); esophageal or lower respiratory tract candidiasis; disseminated cryptococcosis; pulmonary, gastrointestinal, CNS, or ocular cytomegalovirus infection; disseminated herpes simplex infection; and (cancers) Kaposi's sarcoma, primary B-cell lymphoma, and non-Hodgkin's lymphoma
-
clinical findings of common infections are often atypical (e.g., increased frequency of extrapulmonary tuberculosis)
DIAGNOSIS
-
serologic tests for HIV antibodies (ELISA, IFA, Western blot)
-
isolation of virus
INFECTIOUS AGENT
-
human immunodeficiency virus, types 1 and 2 (retroviruses)
-
types 1 and 2 are serologically and geographically distinct but have similar epidemiologic and pathologic characteristics
-
humans are reservoirs
MODE OF TRANSMISSION
-
sexual exposure to an infected person
-
exposure to the blood or blood products (transfusions and needle sharing) or tissues (transplantation) of an infected person
-
transmitted from mother to fetus
-
routine social or community contact with HIV-infected persons carries no risk of transmission
DISTRIBUTION
-
worldwide
-
more than 200,000 reported cases of AIDS in the United States as of January 1992; approximately 1 million additional persons asymptomatically infected with HIV
-
worldwide, 8 to 10 million persons infected with HIV-1 by June 1990
-
HIV-2 is currently endemic only in West Africa, although cases have appeared in Europe, South America, North America, and other parts of Africa
-
cases were initially clustered among male homosexuals, intravenous drug users, prostitutes, and transfusion recipients
-
distribution patterns have changed in the past 10 years and continue to change (fewer cases of transfusion-induced HIV disease, more cases of infection acquired from heterosexual sex, more cases of transplacental transmission)
INCUBATION PERIOD AND COMMUNICABILITY
-
days to months until virus is detectable in the blood
-
months to years before appearance of clinical HIV disease (about half of HIV-infected persons will have developed AIDS 10 years after infection in the absence of specific antiviral treatment)
-
period of communicability is unknown but is presumed to begin early after onset of HIV infection and to extend through life
TREATMENT
-
early recognition and treatment of treatable infections and neoplasms (often chronic suppressive/maintenance therapy is recommended because of high infection relapse rates)
-
there are currently three Food and Drug Administration (FDA)-approved
-
anti-HIV agents: zidovudine (AZT), dideoxyinosine (also known as VIDEX or ddI), and dideoxycytodine (also known as HIVID or ddC; approved for use only in combination with AZT); these agents do not cure HIV disease but have been shown to slow its progression
PREVENTION AND CONTROL
-
screening of blood (and other tissue) donors
-
avoidance of sexual intercourse (vaginal, anal, oral) with persons known or suspected to be infected with HIV
-
use of latex condoms and spermicide to reduce the risk of sexual transmission (there is no risk of HIV transmission in a long-term, mutually monogamous, heterosexual relationship between two partners known not to be infected with HIV)
-
caution by health care workers in handling, using, and disposing of needles and other sharp instruments, and wearing of latex gloves when coming into contact with bodily fluids of any patient
FACTORS FACILITATING EMERGENCE
-
urbanization
-
changes in lifestyles/mores
-
increased intravenous drug abuse
-
international travel
-
medical technology (transfusions)
Human Papillomavirus (HPV)
DISEASE(S) AND SYMPTOMS
-
a variety of skin and mucous membrane lesions, from the common wart to laryngeal warts (in infants infected by their mothers during birth) to venereal warts (most often seen in the moist areas in and around the genitalia and anus)
-
HPV has been strongly implicated in the etiology of cervical cancer (especially HPV types 16 and 18)
DIAGNOSIS
-
usually based on lesion appearance
-
in some cases, excision and histological examination are necessary
INFECTIOUS AGENT
-
human papillomavirus (there are at least 60 types identified)
MODE OF TRANSMISSION
-
usually by direct contact
-
also by autoinoculation (e.g. by a shaving razor) and by contact with contaminated floors
-
genital warts are sexually transmitted
-
virus can be transmitted from mother to infant during birth
DISTRIBUTION
-
worldwide
INCUBATION PERIOD AND COMMUNICABILITY
-
1 to 20 months; average is 2 to 3 months
-
period of communicability is unknown but is probably at least as long as visible lesions persist
TREATMENT
-
freezing of warts with liquid nitrogen
-
application of salicylic acid or podophyllin to remove warts
-
interferon has been shown to be effective in the treatment of genital warts
-
surgical removal or laser therapy is required for laryngeal and cervical warts
PREVENTION AND CONTROL
-
avoidance of direct contact with lesions
-
use of a condom during sexual intercourse
FACTORS FACILITATING EMERGENCE
-
possibly increases in sexual activity
Human Parvovirus B19
DISEASE(S) AND SYMPTOMS
Erythema infectiosum
-
classic infection in childhood is characterized by erythema of cheeks (slapped cheek appearance) and rash on extremities
-
adults have more severe illness, with fever and arthritis that can last for months or years
-
may cause aplastic crisis in patients with chronic hemolytic anemias
DIAGNOSIS
-
made on clinical grounds, can be confirmed by testing for antibodies
INFECTIOUS AGENT
-
human parvovirus B19, a single-stranded DNA virus
MODE OF TRANSMISSION
-
most commonly, contact with infectious respiratory secretions
-
also transmitted transplacentally and via blood and blood products
DISTRIBUTION
-
worldwide; common in children
INCUBATION PERIOD AND COMMUNICABILITY
-
4 to 20 days to development of rash
-
probably not communicable after onset of rash; immunosuppressed persons with chronic infection may be communicable up to years after onset
TREATMENT
-
supportive only
PREVENTION AND CONTROL
-
isolation not practical in community at large
-
hospitalized patients with transient aplastic crisis should be isolated
-
hand washing after patient contact
FACTORS FACILITATING EMERGENCE
-
a pervasive virus that has only recently drawn increased attention
-
as a hematogenous infection, it may increase in importance in immunosuppressed persons and as a threat to the blood supply
Human T-Cell Leukemia Virus (HTLV), Types 1 and 2
DISEASE(S) AND SYMPTOMS
Adult T-cell leukemia/lymphoma (ATLL); chronic progressive myelopathy; tropical spastic paraparesis (TSP)
-
lymphadenopathy, hepatomegaly, splenomegaly, lymphomatous meningitis
-
cutaneous lesions (generalized erythroderma, papules, nodules, plaques, and maculopapular rashes)
fever and abdominal symptoms may occur
-
arthritis is frequently reported
-
disease ranges from subacute to rapidly lethal (median survival for ATLL is 8 months)
DIAGNOSIS
-
isolation of the virus from the blood
-
detection of antibodies
INFECTIOUS AGENT
-
human T-cell leukemia virus
-
type 1 has been implicated in the causation of leukemia and lymphoma by serologic, virologic, and epidemiologic evidence
-
type 2 was initially isolated from two cases of hairy cell leukemia (causality has not yet been established)
MODE OF TRANSMISSION
-
person-to-person transmission by blood (transfusions and shared needles) and by sexual contact
-
transplacental transmission is possible
DISTRIBUTION
-
virus is present on all continents
-
cases of HTLV-1 infection have clustered in the Caribbean, south-western Japan, parts of Central and South America, Africa, Italy, and the southern United States
-
HTLV-2 is commonly found in intravenous drug abusers
INCUBATION PERIOD AND COMMUNICABILITY
-
incubation period is several years and may be as long as 20 years
-
communicability is unknown
TREATMENT
-
response of ATLL to conventional chemotherapeutic regimens has been poor
-
corticosteroids are helpful in some cases
PREVENTION AND CONTROL
-
avoidance of sexual or blood contact with an infected person
-
screening of donated blood for the virus (types 1 and 2)
FACTORS FACILITATING EMERGENCE
-
medical technology (transfusion)
-
possibly increased intravenous drug abuse
Influenza A Virus
DISEASE(S) AND SYMPTOMS
Drift influenza; pandemic influenza
-
sudden onset of fever, myalgias, cough, headache, and profound fatigue
-
nasal discharge, sore throat, and hoarseness are common
-
fever lasts from 1 to 5 days; respiratory symptoms and malaise may persist another 7 to 14 days
-
severe cases involve complications such as pneumonia
-
infection can be fatal, especially in the elderly and in those debilitated by chronic cardiac, pulmonary, renal, or metabolic disease, as well as in the immunosuppressed
-
pandemic influenza is typically more severe, since populations have no immunity to pandemic strains
DIAGNOSIS
-
recognition is commonly by epidemiological characteristics
-
isolation of virus from respiratory tract
-
detection of viral antigen in respiratory secretions
INFECTIOUS AGENT
-
influenza A virus, an RNA virus that undergoes frequent mutations
-
virus isolates are described by character of hemagglutinin (H) and neuraminidase antigens; type A includes 3 subtypes (H1N1, H2N2, and H3N2)
-
emergence of completely new subtypes (antigenic shift) occurs at irregular intervals and typically results in pandemic influenza
-
minor antigenic changes (antigenic drift) are responsible for annual epidemics and regional outbreaks
MODE OF TRANSMISSION
-
airborne spread among crowded populations in enclosed spaces
-
transmission also occurs by direct contact with mucus of an infected person (influenza virus can persist for hours in dried mucus)
-
transmission from animal to human has been demonstrated rarely
DISTRIBUTION
-
worldwide
-
in temperate regions, influenza outbreaks occur during colder months
-
in tropical regions, influenza occurs year round
INCUBATION PERIOD AND COMMUNICABILITY
-
1 to 2 days
-
period of communicability is probably 3 to 5 days from clinical onset
TREATMENT
-
amantadine and rimantadine, if given early, shorten clinical illness in acute influenza A
PREVENTION AND CONTROL
-
immunization (vaccine is less effective in the elderly, in the immunosuppressed, and in people who have chronic renal failure)
-
prophylactic amantadine is recommended for selected individuals (e.g., those at high risk of complications from immunization)
FACTORS FACILITATING EMERGENCE
-
antigenic drift leads to small changes in the virus
-
significant mutations in the virus (antigenic shift) may result from animal-human virus reassortment
Japanese Encephalitis Virus
DISEASE(S) AND SYMPTOMS
Japanese encephalitis virus disease
-
clinical features range from inapparent to fatal
-
mild infections involve fever, headache, and myalgias
-
severe disease involves high fever, nausea, vomiting, and altered consciousness
-
hyperthermia, seizures, paralysis, and coma can occur
-
convalescence is prolonged; up to 80 percent of survivors experience neurologic sequelae
-
with optimal care, case fatality rate is 10 percent (as high as 40 percent in young children and in persons over 65 years of age)
DIAGNOSIS
-
isolation of the virus from cerebrospinal fluid or blood
-
isolation of viral antibodies from the blood and cerebral spinal fluid
INFECTIOUS AGENT
-
Japanese encephalitis virus
-
pigs are important amplification hosts for the virus
MODE OF TRANSMISSION
-
bite of an infective mosquito
-
transplacental transmission has been documented
-
not directly transmitted from person to person
DISTRIBUTION
-
widely distributed in eastern and southern Asia, the far eastern Commonwealth of Independent States, and the Pacific islands
INCUBATION PERIOD
-
6 to 8 days
TREATMENT
-
supportive only
PREVENTION AND CONTROL
-
mosquito control
-
an inactivated vaccine is widely used in Japan (95 percent efficacy in clinical trials)
-
a live, attenuated vaccine has been used in China
FACTORS FACILITATING EMERGENCE
-
changes in agricultural practices facilitating mosquito breeding
Lassa Virus
DISEASE(S) AND SYMPTOMS
Lassa fever
-
gradual onset of fever, malaise, headache, dizziness, and sore throat
-
nausea, vomiting, and diarrhea are common
-
in severe cases, hypotension, shock, and seizures may result
-
acute illness lasts 7 to 31 days, with an average of 12 days
DIAGNOSIS
-
isolation of virus from blood, urine, or throat washings
-
serological tests (ELISA or IFA)
INFECTIOUS AGENT
-
Lassa virus, an arenavirus named after a town in Nigeria
MODE OF TRANSMISSION
-
contact with excreta of infected rodents deposited on surfaces such as beds and floors, or in food
-
transmission also occurs via contact with blood, secretions, or excretions of an infected person
-
transplacental transmission can occur
DISTRIBUTION
-
widely distributed over West Africa, especially Nigeria, Sierra Leone, and Liberia
INCUBATION PERIOD AND COMMUNICABILITY
-
8 to 14 days
-
person-to-person transmission may occur during the acute febrile phase when virus is present in the throat
TREATMENT
-
antiviral agents: ribavirin
-
mechanical ventilation and renal dialysis may be required
PREVENTION AND CONTROL
-
avoidance of contact with rats and infected persons
-
strict isolation of infected persons
FACTORS FACILITATING EMERGENCE
-
unknown
Measles Virus
DISEASE(S) AND SYMPTOMS
Measles
-
fever, conjunctivitis, coryza, cough, and Koplic spots on the buccal mucosa
-
red blotchy rash beginning on forehead and neck, later spreading to trunk and limbs
DIAGNOSIS
-
usually made on clinical and epidemiological grounds
INFECTIOUS AGENT
-
measles virus
MODE OF TRANSMISSION
-
airborne transmission by droplet spread
-
direct contact with the nasal or throat secretions of infected persons
DISTRIBUTION
-
worldwide
-
incidence in a population determined largely by levels of immunization
INCUBATION PERIOD AND COMMUNICABILITY
-
10 to 14 days
-
infective virus is present from the 5th day of incubation through 4 days after onset of rash
-
measles is one of the most highly communicable infectious diseases (measles virus can survive in droplet nuclei for more than 2 hours)
TREATMENT
-
none
PREVENTION AND CONTROL
-
immunization with live measles vaccine
-
children should be kept out of school at least four days after the onset of rash
-
deterioration of public health infrastructure supporting immunization
Norwalk and Norwalk-like Agents
DISEASE(S) AND SYMPTOMS
Gastroenteritis, epidemic diarrhea
-
vomiting, diarrhea, headache, and low-grade fever lasting 2 to 3 days
-
disease often occurs in outbreaks involving people of all age groups
-
identification of the agent in the stool by electron microscopy and/or immunologic assay (RIA and ELISA)
INFECTIOUS AGENTS
-
Norwalk agent (virus-like), Snow Mountain agent, Hawaii agent, and other Norwalk-like agents
MODE OF TRANSMISSION
-
most likely fecal-oral transmission
-
respiratory transmission may occur via aerosolized vomitus
-
alleged vehicles of transmission include drinking water, swimming water, and uncooked foods (shellfish and salads)
DISTRIBUTION
-
worldwide
-
in developing countries, disease is more common in children; in the United States, disease typically occurs in older children and adults
INCUBATION PERIOD AND COMMUNICABILITY
-
typical incubation period is 1 to 2 days
-
disease is communicable up to 2 days after diarrhea stops
TREATMENT
-
supportive only (e.g., oral fluid replacement)
PREVENTION AND CONTROL
-
effective preventive measures are undetermined
-
possibly avoidance of alleged vehicles of transmission
FACTORS FACILITATING EMERGENCE
-
increased recognition
Rabies Virus
DISEASE(S) AND SYMPTOMS
Rabies
-
primarily a disease of animals; all warm-blooded mammals are susceptible
-
acute encephalomyelitis
-
fever, malaise, myalgia, vomiting, agitation or hydrophobia upon attempt to swallow
-
initial symptoms followed by hyperventilation, aphasia, paralysis, seizures
-
cardiac arrhythmias and coma can follow
DIAGNOSIS
-
isolation and identification of rabies virus from saliva, cerebrospinal fluid, urine, brain, or other tissue
INFECTIOUS AGENT
-
rabies virus
-
dogs are most common reservoir host; in some areas, vampire bats, mongooses, wolves, foxes, raccoons, and other wild and domestic animals are important reservoir hosts; also, newly emerging in felines in the eastern United States
MODE OF TRANSMISSION
-
a bite (that breaks the skin) from an infected animal; bites around head, face, or hands carry highest risk of infection
-
mucous membrane exposure to saliva of an infected animal
DISTRIBUTION
-
worldwide; causes an estimated 30,000 human deaths per year, mostly in developing countries
INCUBATION PERIOD AND COMMUNICABILITY
-
1 to 2 months
-
period of communicability for animals includes week before clinical signs and throughout the course of the disease
TREATMENT
-
immediate and thorough cleansing of bite wound
-
administration of rabies immune globulin (RIG) around wound and intramuscularly to prevent infection, and vaccine intramuscularly to prevent infection
-
the only treatment for disease is supportive; more than 99% of patients with symptomatic infection die
PREVENTION AND CONTROL
-
pre-exposure vaccination is recommended for persons whose occupations or travel will place them at risk for exposure to rabid animals
-
vaccination of dogs and cats
-
isolation and destruction of infected animals
FACTORS FACILITATING EMERGENCE
-
changing movements of reservoir host species
-
absence or failure of rabies control programs
Rift Valley Fever Virus
DISEASE(S) AND SYMPTOMS
Rift Valley fever
-
abrupt onset of fever, severe headache, myalgias, and arthralgias
-
complications include jaundice and hemorrhagic complications
-
encephalitis and retinitis may occur
-
some survivors are left with neurologic sequelae and permanent visual damage
-
(in animals: enzootic hepatitis)
DIAGNOSIS
-
virus isolation from the blood
-
demonstration of virus antibodies in the cerebrospinal fluid or acute serum
INFECTIOUS AGENT
-
Rift Valley fever virus
MODE OF TRANSMISSION
-
bite of an infective mosquito
-
contact with infected animals or their tissues
-
possible transmission via unpasteurized milk
-
not directly transmitted from person to person
DISTRIBUTION
-
widespread in Africa; initially described in Rift Valley in Kenya
INCUBATION PERIOD
-
3 to 5 days
TREATMENT
-
supportive only
PREVENTION AND CONTROL
-
an inactivated vaccine is available for persons at high risk of infection (veterinarians, laboratory personnel) in endemic areas
-
a candidate live, attenuated vaccine is under development
-
immunization of animals
-
mosquito control
FACTORS FACILITATING EMERGENCE
-
importation of infected mosquitoes and/or animals
-
creation of mosquito habitats through dam building and irrigation
Ross River Virus
DISEASE(S) AND SYMPTOMS
Ross River fever
-
a self-limited disease characterized by arthritis (especially in the wrist, knee, ankle, and small joints of the extremities), which lasts from days to months
-
a maculopapular rash on the trunk and limbs commonly follows the onset of arthritis; rash resolves within 7 to 10 days
-
fever is frequently present, lasting 6 to 7 days
-
in 25 percent of cases, rheumatic symptoms continue one year or longer
DIAGNOSIS
-
isolation of virus from serum
-
detection of virus antibodies in serum
INFECTIOUS AGENT
-
Ross River virus
MODE OF TRANSMISSION
-
bite of an infective mosquito
-
transplacental transmission may occur
-
not directly transmitted from person to person
-
virus reservoir is probably the kangaroo
DISTRIBUTION
-
Australia, Tasmania, Papua New Guinea, Indonesia, and several South Pacific islands
INCUBATION PERIOD
-
3 to 11 days
TREATMENT
-
supportive only
PREVENTION AND CONTROL
-
mosquito control
FACTORS FACILITATING EMERGENCE
-
importation of infected mosquitoes and/or travel by infected people
-
creation of mosquito habitats through dam building and irrigation
Rotavirus
DISEASE(S) AND SYMPTOMS
Rotaviral enteritis
-
varies from asymptomatic to severe and sometimes fatal gastroenteritis; group A viruses predominate in infants and young children, group B in older children and adults
-
watery diarrhea, vomiting, low-grade fever, and dehydration
-
illness typically lasts 3 to 10 days
DIAGNOSIS
-
identification of the virus in the stool by immunologic assay (ELISA), electron microscopy, or isolation in cell culture
INFECTIOUS AGENT
-
one of three groups (A, B, or C) of rotavirus (A is the most common cause of illness in humans)
MODE OF TRANSMISSION
-
primarily fecal-oral
-
fecal-respiratory transmission may also occur
DISTRIBUTION
-
worldwide
INCUBATION PERIOD AND COMMUNICABILITY
-
incubation period is 1 to 2 days
-
virus shedding occurs throughout duration of illness and continues for several days following the disappearance of symptoms
TREATMENT
-
supportive only (e.g., oral fluid replacement)
PREVENTION AND CONTROL
-
effective preventive measures are uncertain
-
avoid exposure of infants to persons with acute gastroenteritis
-
passive immunization by oral immunoglobulin has been effective in protecting low-birth-weight newborns
-
a number of oral vaccines are in various stages of development
FACTORS FACILITATING EMERGENCE
-
increased recognition
Venezuelan Equine Encephalitis (VEE) Virus
Disease(s) and Symptoms
Venezuelan equine encephalitis
-
sudden onset of fever, chills, severe headache, nausea, and vomiting
-
pharyngitis and facial erythema may be present
-
central nervous system manifestations (stupor, coma, seizures, and spastic paralysis) can accompany severe cases
-
most infections are fairly mild; symptoms last 3 to 5 days
-
in patients with encephalitis, illness typically lasts 3 to 7 days
DIAGNOSIS
-
isolation of the virus or of viral antibodies in the blood
-
sometimes based on epidemiological grounds (in areas that have experienced a recent equine epizootic)
INFECTIOUS AGENT
-
Venezuelan equine encephalomyelitis virus
-
virus is maintained in rodents
-
transmission cycle involves horses, which serve as the major source of virus to infect mosquitoes
MODE OF TRANSMISSION
-
bite of an infective mosquito
-
transmission also occurs transplacentally and in laboratories via inhalation
-
not directly transmitted from person to person
-
no evidence of aerosol transmission from horses to humans
DISTRIBUTION
-
disease is enzootic and epizootic in tropical South America, Central America, the Caribbean, southern North America, and Mexico
INCUBATION PERIOD
-
2 to 5 days
TREATMENT
-
supportive only
PREVENTION AND CONTROL
-
mosquito control
-
a live, attenuated vaccine is available for laboratory workers and other adults at high risk of infection
-
a killed, attenuated vaccine exists for cases in which the live vaccine is ineffective
-
control of infection in horses by vaccination
FACTORS FACILITATING EMERGENCE
-
introduction into new regions via infected mosquitoes and horses
Yellow Fever Virus
DISEASE(S) AND SYMPTOMS
Yellow fever
-
clinical features range from inapparent to fatal
-
typical attacks are characterized by abrupt onset, fever, chills, headache, muscle pain, nausea, and vomiting
-
as disease progresses, jaundice, hemorrhagic complications, and renal failure may occur
-
pulse may be slow despite high fever
-
the case fatality rate among indigenous populations of endemic regions is less than 5 percent; this rate may exceed 50 percent among nonindigenous groups and in epidemics
-
recovery is slow but complete in survivors
DIAGNOSIS
-
isolation of virus from the blood
-
demonstration of viral antigen in the blood or liver tissue by ELISA
INFECTIOUS AGENT
-
Yellow fever virus
MODE OF TRANSMISSION
-
bite of an infective mosquito
-
not directly transmitted from person to person
DISTRIBUTION
-
disease is endemic in tropical South and Central America and in Africa
-
potential for outbreaks exists in other areas where vector mosquito is found (including the United States)
INCUBATION PERIOD
-
range is 3 to 14 days; usually 1 to 6 days
-
blood of patients is infective for mosquitoes 3 to 5 days after onset of illness
TREATMENT
-
supportive only
PREVENTION AND CONTROL
-
a live viral vaccine prepared from chick embryos is safe and highly effective (more than 95 percent of those vaccinated will have immune response within 7 to 10 days; immunity lasts at least 10 years)
-
mosquito control
FACTORS FACILITATING EMERGENCE
-
lack of effective mosquito control
-
lack of widespread vaccination
-
urbanization in the tropics
-
increased air travel
EMERGENT PROTOZOANS, HELMINTHS, AND FUNGI
Anisakis
DISEASE(S) AND SYMPTOMS
Anisakiasis, herring worm disease, cod worm disease
-
severe epigastric pain, nausea, vomiting, fever
-
obstruction, ulceration, and bleeding in the gastrointestinal tract are possible
DIAGNOSIS
-
recognition of the 2 to 3 cm. larva invading the oropharynx
-
visualization of larvae through gastroscopic examination
INFECTIOUS AGENT
-
larval nematodes of the Anisakidae family, common parasites of marine mammals and fish
MODE OF TRANSMISSION
-
ingestion of larvae in raw or undercooked fish, squid, or octopus (larvae are colorless, tightly coiled, and not easily seen in fish flesh)
-
not transmitted directly from person to person
DISTRIBUTION
-
most cases are reported from Japan
-
cases are also sporadically reported from North and South America, Europe, Asia, and the South Pacific
-
infected fish can potentially be shipped to any region of the world
INCUBATION PERIOD
-
1 to 12 hours for gastric attachment; 7 to 14 days for intestinal attachment
TREATMENT
-
endoscopic removal of larva
-
surgery may be necessary to remove obstruction
PREVENTION AND CONTROL
-
heating marine fish to 140°F for 10 minutes or freezing at -4°F for at least five days kills the larvae
FACTORS FACILITATING EMERGENCE
-
increasing popularity of raw fish dishes in the United States and elsewhere
Babesia
DISEASE(S) AND SYMPTOMS
Babesiosis
-
fever, fatigue, chills, and hemolytic anemia lasting from several days to a few months
DIAGNOSIS
-
blood smear contains red blood cells with visible parasites
INFECTIOUS AGENT
-
Babesia microti and other Babesia species (protozoan parasites)
-
nymphal Ixodes ticks (carried by deer mice) are vectors; adult ticks live on deer
MODE OF TRANSMISSION
-
bite of a nymphal Ixodes tick
-
not directly transmitted from person to person
-
occasional transmission by blood transfusion has been reported
DISTRIBUTION
-
widespread in areas where ticks are present
-
majority of cases are from northeastern United States
-
also reported from France and other European countries
INCUBATION PERIOD
-
variable; 1 week to 12 months reported
TREATMENT
-
a combination of antiparasitic agents (clindamycin and quinine) has been effective in most patients
-
exchange blood transfusion may be required in patients with very high-grade parasitemia
PREVENTION AND CONTROL
-
avoidance of tick exposure in endemic areas (protective clothing, tick repellant)
-
control of rodents around human habitations
FACTORS FACILITATING EMERGENCE
-
reforestation and subsequent increase in deer population
-
housing development in wooded areas
Candida
DISEASE(S) AND SYMPTOMS
Candidiasis
-
fungal infections usually confined to the superficial layers of skin or mucous membranes: oral thrush, intertrigo, vulvovaginitis, paronychia, or onychomycosis
-
ulcers may be formed in the esophagus, gastrointestinal tract, or bladder
-
dissemination in the blood may produce lesions in other organs (kidney, spleen, liver, lung, endocardium, eye, or brain)
DIAGNOSIS
-
microscopic demonstration of yeast cells in infected tissue or body fluid
-
fungal culture
INFECTIOUS AGENT
-
species of the fungus, Candida
MODE OF TRANSMISSION
-
contact with secretions or excretions of mouth, skin, or vagina of infected persons, or with the feces of infected persons
-
passage from mother to infant during childbirth
-
endogenous spread
-
disseminated candidiasis can originate from indwelling urinary catheters and percutaneous intravenous catheters
DISTRIBUTION
-
worldwide
-
the fungus (C. albicans) is often part of the normal human flora
INCUBATION PERIOD AND COMMUNICABILITY
-
incubation period is variable
-
infection is presumably communicable while lesions are present
TREATMENT
-
topical antifungal agents: imidazole, nystatin
-
oral clotrimazole troches or nystatin suspension is effective for treatment of oral thrush
-
oral ketoconazole is effective for treatment of infected skin and mucous membranes of the mouth, esophagus, and vagina
PREVENTION AND CONTROL
-
detection and treatment of infection early to prevent systemic spread
-
detection and treatment of vaginal candidiasis during third trimester of pregnancy to prevent neonatal thrush
-
amelioration of underlying causes of infection (e.g., removal of indwelling venous catheters)
FACTORS FACILITATING EMERGENCE
-
immunosuppression
-
medical management (catheters)
-
antibiotic use
Crytococcus
DISEASE(S) AND SYMPTOMS
Cryptococcosis
-
a fungal infection, usually presenting as a subacute or chronic meningitis
-
skin may show acneiform lesions, ulcers, or subcutaneous tumor-like masses
-
infection of lungs, kidneys, prostate, bone, and liver may occur
-
untreated cryptococcal meningitis terminates fatally within several months
DIAGNOSIS
-
visualization of fungus on microscopic examination of cerebrospinal fluid
-
tests for antigen in serum and cerebrospinal fluid
INFECTIOUS AGENT
-
Crytococcus species, typically C. neoformans, a fungus
-
fungus grows saprophytically in external environment (can be isolated from the soil in many parts of the world)
-
fungus can consistently be isolated from old pigeon nests and pigeon droppings
MODE OF TRANSMISSION
-
presumably by inhalation
-
waterborne transmission can also occur
-
not transmitted directly from person to person or between animals and people
DISTRIBUTION
-
worldwide
-
infection occurs mainly in adults
-
disseminated or central nervous system cryptococcosis is often a sentinel infection for HIV-infected persons
-
infection also occurs in dogs, cats, horses, cows, monkeys, and other animals
INCUBATION PERIOD
-
unknown
TREATMENT
-
antifungal agents: amphotericin B is effective in many cases
-
very difficult to cure in persons with HIV disease
PREVENTION AND CONTROL
-
careful removal (preceded by chemical decontamination and wetting with water or oil to prevent aerosolization) of large accumulations of pigeon droppings
FACTORS FACILITATING EMERGENCE
-
immunosuppression
Cryptosporidium
DISEASE(S) AND SYMPTOMS
Cryptosporidiosis
-
a parasitic infection of the epithelial cells of the gastrointestinal, biliary, and respiratory tracts of man, as well as other vertebrates (birds, fish, reptiles, rodents, cats, dogs, cattle, and sheep)
-
symptoms of infection include watery diarrhea, nausea, vomiting, malaise, myalgias, and, in about half of cases, fever
-
symptoms usually come and go, but subside in fewer than 30 days in most healthy, immunocompetent persons
-
immunocompromised persons may not be able to clear the parasite, with disease becoming prolonged and fulminant and contributing to death
DIAGNOSIS
-
identification of oocysts in fecal smears
-
identification of parasites in intestinal biopsies
INFECTIOUS AGENT
-
Cryptosporidium, a protozoan parasite
MODE OF TRANSMISSION
-
fecal-oral spread from contaminated fingers, food, and water
-
occasional transmission by aerosolized organisms has been reported
DISTRIBUTION
-
worldwide; organism has been found wherever sought
INCUBATION PERIOD AND COMMUNICABILITY
-
probably 1 to 12 days
-
oocysts, the infectious stage of the parasite, appear in the stool from the onset of symptoms to several weeks after symptoms resolve
-
outside the body, oocysts can remain infective for 2 to 6 months in a moist environment
TREATMENT
-
fluid and electrolyte replacement; nutritional support
-
effective, specific therapy has not yet been identified
PREVENTION AND CONTROL
-
careful handling of animal excreta
-
hand washing by those in contact with calves and other animals with diarrhea
-
effective water treatment
FACTORS FACILITATING EMERGENCE
-
development near watershed areas
-
immunosuppression
Giardia lamblia
DISEASE(S) AND SYMPTOMS
Giardiasis
-
infection of the upper small intestine
-
frequent diarrhea, bloating, abdominal cramps, fatigue, low-grade fever, malaise, and weight loss
-
symptoms typically subside after 2 to 3 weeks, but chronic or relapsing diarrhea may occur
DIAGNOSIS
-
identification of cysts or trophozoites in feces or of trophozoites in biopsy material from the small intestine
INFECTIOUS AGENT
-
Giardia lamblia, a protozoan parasite
MODE OF TRANSMISSION
-
ingestion of cysts in fecally contaminated food or water
-
direct person-to-person spread via hand-to-mouth transfer of cysts from an infected individual (especially in day care centers and chronic care institutions)
DISTRIBUTION
-
worldwide; causes both sporadic outbreaks and epidemics
INCUBATION PERIOD AND COMMUNICABILITY
-
incubation period ranges from 3 days to 6 weeks; usually 1 to 3 weeks
-
infected persons can be a source of infection for as long as they carry the organism
TREATMENT
-
antiparasitic agents: quinacrine, metronidazole, furazolidine
PREVENTION AND CONTROL
-
avoidance of drinking untreated surface water
-
disposal of feces in a sanitary manner
FACTORS FACILITATING EMERGENCE
-
infection in the animal population (beavers and dogs)
-
capability of the organism to survive in water supply systems that use superficial water
-
immunosuppression
-
international travel
Microsporidia
DISEASE(S) AND SYMPTOMS
Microsporidiosis
-
chronic gastroenteritis, diarrhea, and wasting in patients with HIV disease
-
conjunctivitis, scleritis, diffuse punctate keratopathy, and corneal ulceration have also been reported, primarily in patients with HIV disease
-
other findings include fever, hepatitis, muscle weakness, and neurologic changes
DIAGNOSIS
-
requires electron microscopy of biopsy specimen
INFECTIOUS AGENT
-
protozoan parasites from the phylum Microspora (phylum consists of about 80 genera, of which at least four cause human disease: Encephalitozoon, Enterocytozoon, Nosema, and Pleistophora)
-
microsporidia typically infect animals and have only recently been recognized as human pathogens
MODE OF TRANSMISSION
-
unknown; probably by ingestion of contaminated food or water
-
spores of some species survive up to 4 months in the environment
DISTRIBUTION
-
worldwide
-
human infections have been reported from Africa, North and South America, Asia, and Europe
-
the majority of reported patients have been immunosuppressed
INCUBATION PERIOD AND COMMUNICABILITY
-
unknown
TREATMENT
-
no clearly effective therapy is available
-
some patients have improved with antiparasitic drugs pyrimethamine and metronidazole
PREVENTION AND CONTROL
-
unknown at this time
FACTORS FACILITATING EMERGENCE
-
immunosuppression
-
parasite is newly recognized
Plasmodium
DISEASE(S) AND SYMPTOMS
Malaria
-
fever, headache, nausea, vomiting, diarrhea, myalgias, and malaise
-
in 30 to 40 percent of acute cases, the spleen is enlarged and liver may be tender
-
respiratory and renal failure, shock, acute encephalopathy, pulmonary
-
and cerebral edema, coma, and death may result from severe cases (especially P. falciparum infections)
-
duration of an untreated primary attack ranges from 1 week to 1 month or longer; relapses of febrile illness can occur at irregular intervals for up to 2 to 5 years
-
chronically infected persons develop hyperreactive malarial splenomegaly or nephrotic syndrome
-
case fatality rates among untreated children and nonimmune adults exceed 10 percent
DIAGNOSIS
-
identification of characteristic intraerythrocytic parasites on a blood smear
INFECTIOUS AGENT
-
Plasmodium falciparum, P. vivax, P. ovale, and P. malariae
-
protozoan parasites with an asexual cycle in humans and sexual cycle in mosquitoes
MODE OF TRANSMISSION
-
bite of an infective mosquito
-
not directly transmitted from person to person
-
transmission by transfusion and transplacental transmission account for a small percentage of infections
DISTRIBUTION
-
indigenous malaria persists in about 100 tropical and subtropical countries
-
disease occurs in Africa, Asia, Mexico, Central and South America, the Caribbean, the South Pacific Islands, and in parts of the Commonwealth of Independent States
-
worldwide, an estimated 200 to 300 million infections occur annually, with 2 to 3 million deaths (most are from P. falciparum)
-
chloroquine-resistant P. falciparum strains have been reported from endemic areas in Africa, Asia, and the Americas; continued spread of resistance is expected
INCUBATION PERIOD
-
10 to 30 days, depending on virus strain
-
transmission by transfusion can occur as long as asexual forms of the parasite remain in the circulating blood (for P. malariae, this can be more than 40 years)
TREATMENT
-
chloroquine is drug of choice unless resistant P. falciparum is suspected
-
quinine plus tetracycline, pyrimethamine and sulfadiazine/clindamycin, or mefloquine should be used for resistant P. falciparum strains
-
resistance of P. falciparum malaria to all antimalarials has been reported; in these cases, combination therapy and repeated courses of treatment may be necessary
PREVENTION AND CONTROL
-
mosquito control
-
chemoprophylactic regimens (be sure to obtain updated information)
FACTORS FACILITATING EMERGENCE
-
urbanization
-
changing parasite biology
-
environmental changes
-
drug resistance
-
air travel
Pneumocystis carinii
DISEASE(S) AND SYMPTOMS
Pneumocystis carinii pneumonia
-
progressive dyspnea, tachypnea, and cyanosis
-
pneumonia is often fatal in malnourished, chronically ill, and premature infants, as well as in adults who are immunocompromised
DIAGNOSIS
-
demonstration of the organism in material from bronchial brushings, open lung biopsy, and lung aspirates
-
no satisfactory culture method or serologic test is in routine use at present
INFECTIOUS AGENT
-
Pneumocystis carinii, a protozoan parasite (with genetic similarities to a fungus)
MODE OF TRANSMISSION
-
unknown in man (airborne transmission has been reported in rats)
-
subclinical infection may be common
DISTRIBUTION
-
worldwide
-
the disease affects 60 percent of patients with human immunodeficiency virus (HIV) disease
INCUBATION PERIOD AND COMMUNICABILITY
-
unknown; symptoms typically appear 1 to 2 months after onset of immunosuppression
-
period of communicability is unknown
TREATMENT
-
cotrimoxazole is first choice drug; pentamidine is also used
PREVENTION AND CONTROL
-
prophylaxis with cotrimoxazole in immunocompromised patients
FACTORS FACILITATING EMERGENCE
-
immunosuppression
Strongyloides stercoralis
DISEASE(S) AND SYMPTOMS
Strongyloidiasis
-
transient rash at site of parasite penetration into the skin
-
coughing and wheezing may develop when parasite passes through lungs
-
abdominal symptoms occur when adult female parasite invades intestinal mucosa
-
abdominal pain, diarrhea, nausea can be chronic and relapsing
-
in the immunocompromised host, infection may become disseminated, resulting in wasting, pulmonary involvement, and death
DIAGNOSIS
-
identification of larvae in stool specimens or duodenal aspirates
INFECTIOUS AGENT
-
Strongyloides stercoralis, a nematode
-
larvae penetrate skin, enter blood vessels, travel to lungs, migrate up respiratory tree to the pharynx, where they enter the gastrointestinal tract (where the female lays eggs)
MODE OF TRANSMISSION
-
penetration of skin or mucous membrane by infective larvae (usually from fecally contaminated soil)
-
free-living form of the parasite can be maintained in the environment (soil) for years
-
transmission also occurs via oral-anal sexual activities
DISTRIBUTION
-
worldwide; most common in tropical and subtropical areas
INCUBATION PERIOD AND COMMUNICABILITY
-
larvae can be found in stool 2 to 3 weeks after exposure
-
infection is potentially communicable as long as living worms remain in the intestine
TREATMENT
-
antiparasitic agents: thiabendazole, albendazole, ivermectin
PREVENTION AND CONTROL
-
disposal of feces in a sanitary manner
-
avoidance of skin-soil contact in endemic areas
FACTORS FACILITATING EMERGENCE
-
international travel
-
immunosuppression
Toxoplasma gondii
DISEASE(S) AND SYMPTOMS
Toxoplasmosis
-
a systemic protozoan disease, frequently present as an acute mononucleosis-like disease (malaise, myalgias, fever)
-
immunocompromised persons tend to have severe primary infection with pneumonitis, myocarditis, meningoencephalitis, hepatitis, chorioretinitis, or some combination of these
-
congenital toxoplasmosis causes chorioretinitis, fever, jaundice, rash, and brain damage
DIAGNOSIS
-
based on clinical signs, as well as on demonstration of the organism in body tissues or fluids
INFECTIOUS AGENT
-
Toxoplasma gondii, a protozoan parasite
-
cats and other felines are reservoirs
-
intermediate hosts are sheep, goats, rodents, swine, cattle, chicken, and birds
MODE OF TRANSMISSION
-
ingestion of oocysts (on fingers or in food contaminated with cat feces) or cysts in raw or undercooked meat
-
transplacental transmission
-
transmission through blood transfusion and tissue transplantations has been reported
-
not directly transmitted from person to person (except in utero)
DISTRIBUTION
-
worldwide
-
prevalence of seropositivity is higher in warm, humid climates and is influenced by presence of cats and by eating habits
INCUBATION PERIOD
-
1 to 3 weeks
TREATMENT
-
antiparasitic agents (pyrimethamine plus sulfadiazine) for persons with severe disease
-
no treatment is needed for most healthy, immunocompetent hosts
PREVENTION AND CONTROL
-
thorough cooking of meats
-
daily disposal of cat feces and disinfection of litter pans (pregnant women should avoid contact with litter pans)
-
thorough hand washing after handling of raw meat
-
prophylactic treatment for patients with HIV disease
FACTORS FACILITATING EMERGENCE
-
immunosuppression
-
increase in cats as pets