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Emerging Infections: Microbial Threats to Health in the United States
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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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)
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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)
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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
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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
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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
Representative terms from entire chapter:
incubation period