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3
Surveillance
OVERVIEW
Infectious disease surveillance is the first link in the response to emerging in-
fections. The United States spent $74.5 million in 1992 for all infectious disease
surveillance activities (Osterholm et al., 1993~. Although the total amount of sur-
veillance has increased in recent years, there have been dramatic cutbacks in sur-
veillance for human immunodeficiency virus (HIV) infection, tuberculosis, and
vaccine-preventable diseases (Michael Osterholm, state epidemiologist and chief,
Minnesota Department of Health, personal communication, November 1998~.
Infectious disease surveillance concurrently involves the health care deliv-
ery system, the public health laboratory, and epidemiologists. Each of these
sectors contributes to the four basic components of surveillance, which are (1)
collection, (2) analysis, (3) dissemination, and (4) response. Collection and
analysis can be conducted at the local, state, federal, or international level by
public agencies as well as by private industry. Dissemination and response are
specific public health activities. Thus, disease surveillance is the ongoing, sys-
tematic collection and analysis, interpretation, and feedback of outcome-specific
data. As such, surveillance may monitor cases of disease reported by clinicians
or identified in laboratories, or it may monitor changes in practice or other be-
haviors of public health importance.
Relevant activities at the federal level include assessment of surveillance
programs, funding of state activities, provision of services, and nationwide dis-
ease surveillance. At the state level, health departments establish the systems by
which infection and disease are reported, data are gathered, and prevention is
initiated. State and local health departments also play a vital role in educating
42
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SURVEILLANCE
43
physicians about the need to report and gather appropriate data. In the private
sector, pharmaceutical companies and organizations that provide diagnostic
services play a critical role in conducting large-scale surveillance for drug and
vaccine development and in providing clinical data for retrospective and pro-
spective studies.
Surveillance information is derived from many sources, and approaches to
surveillance may vary depending on the kind of information that is needed and
the resources that are available. Surveillance information is used in a variety of
ways: to identify cases for investigation, to estimate magnitude of disease, to
detect outbreaks, to evaluate response and prevention measures, to monitor
changes in infectious agents, to facilitate research, and to measure the impacts of
changes in health care practices.
Although there are common uses of surveillance data at the local, state, and
federal levels, emphases vary. For example, individual case investigation is
critical at the local and state levels but less critical at the federal level, unless a
multijurisdictional disease outbreak occurs. Evaluation of larger-scale preven-
tion and control measures for example, the impact of new vaccines is a high
priority at the federal level. A national surveillance plan should take into ac-
count this diversity in the uses of data, approaches, and emphases at different
government levels.
GAO REPORT ON PUBLIC HEALTH SURVEILLANCE OF
EMERGING INFECTIOUS DISEASES
Marsha Lillie-Blanton, Ph.D., Associate Director, and
Helene Toiv, M.P.A., Assistant Director,
Health, Education, and Human Services Division,
U.S. General Accounting Office
A number of changes in the health care system such as consolidations and
managed care~ombined with recent outbreaks of infectious diseases thought
to be under control have led policy makers to evaluate, among other things, the
functioning of public health and clinical laboratories. One such assessment was
conducted by the U.S. General Accounting Office (GAO), a research agency of
the U.S. Congress.
The GAO focused its effort on four tasks: (1) to describe the roles of differ-
ent categories of private and public laboratories; (2) to gather information on the
extent to which state surveillance programs and state public health laboratories
contribute to the surveillance of six specific diseases;) (3) to define the problems
iThe six specific diseases were tuberculosis, shigella toxin producing Escherichia
cold infections, pertussis, cryptosporidiosis, hepatitis C, and penicillin-resistant strepto-
coccal pneumonia. The diseases were chosen to represent various modes of transmission
(foodborne, waterborne, and airborne) and different levels of antimicrobial resistance.
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44
PUBLIC HEALTH SYSTEMS AND EMERGING INFECTIONS
faced by public health officials, particularly at the state level, in gathering and
using laboratory-generated information; and (4) to report on the role of the
Centers for Disease Control and Prevention (CDC), particularly the kind of as-
sistance it provides to the states. To conduct the assessment, GAO surveyed all
state public health laboratory directors and all state epidemiologists and con-
ducted case studies in Oregon, Kentucky, and New York.
GAO's survey gathered information about the kinds of tests that the state
public health laboratories performed in connection with the selected diseases,
whether the state epidemiology program includes the six diseases in its surveil-
lance program, and reporting requirements. Data were also collected on re-
sources, both financial and human, and electronic communications. State officials
were also asked about the assistance they received from CDC (see Box 3_1~.2
Summary findings Tom the survey are found in Appendix C.
EMERGING INFECTIONS PROGRAM
COOPERATIVE AGREEMENT
Robert Pinner, M.D.
Director, Office of Surveillance, National Center for Infectious Diseases,
Centers for Disease Control and Prevention
Following publication of the 1992 Institute of Medicine (IOM) report
Emerging Infections: Microbial Threats to Health in the United States (IOM,
1992), CDC developed a plan to address emerging infections. It was released in
April 1994, and was recently revised and updated. Since then, progress has been
made in implementing this plan. The plan has the following four goals: (1) sur-
veillance and response, (2) applied research, (3) infrastructure and training, and
(4) prevention and control. In addition, among other activities, CDC sponsors
the Emerging Infectious Diseases Journal, the CDC Association of Public
Health Laboratory Directors, and public health laboratory fellowships, and pro-
vides support for World Health Organization collaborating centers.
2Data may be found in the GAO report issued after the workshop was held, titled,
Emerging Infectious Diseases: Consensus on Needed Laboratory Capacity Could
Strengthen Surveillance, (GAO/HEHS-99-26, February 5, 1999~. A copy of this report
may be obtained by calling (202) 512-6000, faxing a request to (202) 512-6061, or
through the GAO website at http://www.gao.gov (select GAO Reports and Testimony,
select FY 1999 from the Annual Indexes, select the Authoring Division index, select
Health, Education, and Human Services, choose HEHS-99-26~.
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SUR VEILLANCE
45
1 BOX3-1 GAO Re HS-99-26 1
I Emerging Innocuous Discas~sensus on Needed
Laborafory~aci~=u/~StrengthenSurveR/ance
~: ~ ~~ . - ~ ~~: ~ :~ ~~: :~:: ~~:~ ~~ ~~. If: :~ ~~:~
~ ~ ~ ~ :~: ~ ::: : ~1
i::
~ ~ ,~ ~~.~.~.~.~.~.~.~ ~~ ~~ ~~ ~~ ~ :
~ ~'~
:~:i~nfebti~ous~d~i~seases~ ep'~de~m~fo:log~y: programs that report d~sease-related Perform
matio~n~:~:d~imct~ly~to~:~C~D:C.~:~:One:~ of ~~the:~fi:nd~in~gs~repo:ried~t~hat~ many~:~state~ :la~bora- :~
Stormy directors and epidemiolo~g~sts ~~1-t that--inadequate stuffings and~:informa-:
:~: ~tion~-sha~ri~ng ~p~blems~h~in:der~the~r Ability -to Generate and use laboratory data
for surveillance Activities. Because public health~fi£ials~ ~have:~:~not~agreed~: Olin :
:~ a definition outlining the minimums Capabilities that state and ~!oca:l health:~de-
:~ ~p~artments~ need Into Conduct ~inlectiou~s~disease~s~ume:i}lance, ~ this lack of~co~n-
se~nsus has ultimately made~it~diffioult ~r~policy~ma~kers to assess th~e~ade-~
~ ~ quaky of existing :~resou~rces four Into determine ~~ where~nvestments~ are mostly ~
:~ ~~ Needed. The: ~O::~:~has~: ~~there~re~recommer~ded~ ~ ~~:h~at~the~ ~;Di~rectors:~: Aloft: G~DC~ ::
lead: an efforts atoll :he~lp ~ ~de~ral~:~sta~:~ And ~ loyal public :health officials create
Consensus on the wren capabilities needed at~each~Ievel for ~aove~rnme~nt.~: : ~
:: ~ : ~ :: ~ ::::
CDC's emerging infectious disease surveillance strategy makes an effort to
take into account the diversity of needs and approaches through three comple-
mentary cooperative agreement programs: (1) the Epidemiology and Laboratory
Capacity (ELC) program, (2) the Emerging Infections Program (EIP) network,
and (3) provider-based sentinel networks. (See Figure 3-1 for a map of program
locations; for more information, see the CDC website: www.cdc.gov.)
The purpose of the ELC program is to assist state and large local public
health agencies in strengthening their basic epidemiological and laboratory ca-
pacities. It currently covers 30 jurisdictions, with full implementation of ELCs
expected by the year 2002. (Essentially there would be ELCs in 63 jurisdictions,
including states, large cities, and territories.) Health departments use these funds
in a variety of ways, although the amount of total resources available is small
relative to the needs. The ELC program has highlighted the challenge to define
more clearly the required core laboratory and epidemiological capacities for the
local, state, regional, and national levels and for various program areas, such as
infectious diseases, foodbome diseases, and bioterrorism. A variety of activities
are pursued in ELC program cooperative agreements, including enhanced in-
formation exchanges, training, education, and laboratory capacity, particularly
including Pulsed Field Gel Electrophoresis (PFGE). Some states have been em-
phasizing collaborations with local health departments.
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46
PUBLIC HEALTH SYSTEMS AND EMERGINrG INFECTIONS
.. ~
.
· EIP/ELC
· ELC
__
__
U
FIGURE 3-1. Map of Emerging Infections Programs (EIP) and Epidemiology and Epi-
demiology and Laboratory Capacity (ELC) Cooperative Agreements. SOURCE: CDC,
1998.
Eight EIP network sites distribute their activities among a variety of
emerging infections program foci, including activities that address foodborne
diseases (FoodNet); a family of project activities that involve invasive bacterial
diseases (Active Bacterial Core surveillance, or ABCs); and surveillance for
unexplained deaths and critical illnesses. Other activities include programs on
judicious antibiotic use, surveillance for hepatitis, and enhancing the rate of im-
munization against pneumococcal infection. Full implementation of EIPs (in 10
jurisdictions total) is expected by the year 2002.
Population-based surveillance information plays a critical role across the
EIP network. For example, all the sites perform active laboratory-based
surveillance for invasive pneumococcal disease. Cases are defined by the
isolation of Streptococcus pneumonias from normally sterile sites, usually blood
or cerebrospinal fluid. Such cases are sought actively by regular contact with the
laboratories. Efforts are made to ensure that the data are comparable across sites
and that there is essentially complete case ascertainment. This approach requires
considerable effort and coordination among the sites and at CDC.
During 1995 and 1996 the incidence of invasive pneumococcal disease
varied substantially across the sites, from 14.2/100,000 population in Toronto to
more than 30/100,000 population in California and Georgia (see Figure 3-2~. A
convenience sample of pneumococcal isolates from assorted laboratories could
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SUR VEILLANCE
47
not be used to characterize incidence in this way or demonstrate with confidence
geographic variations in incidence. Rates of invasive pneumococcal disease vary
considerably by age and race, which, along with the geographic distribution of
underlying diseases like HIV infection that predispose individuals to pneumo-
coccal disease, account for the geographic variations in the incidence of invasive
pneumococcal disease.
Active surveillance entails the collection of isolates, as well as case reports.
Through such means of active surveillance, isolates have been tested at a com-
mon laboratory by reliable methods to measure penicillin susceptibility. The
proportion of penicillin-resistant and -intermediate resistant isolates varies by
site (see Figure 3-3~. The distribution of penicillin resistance and intermediate
resistance also varies by age, with the highest proportion of resistant and inter-
mediate isolates found in young children. In some areas the distribution varies
by race with whites having a higher proportion of infection with resistant iso-
lates than blacks (though blacks have a higher overall incidence of pneumococ-
cal disease).
Another example of population-based surveillance in the EIPs is a set of
activities called FoodNet. FoodNet is designed to determine and monitor the
burden of foodborne diseases and improve understanding of the proportion of
foodborne diseases attributable to various pathogens. Active laboratory-based
surveillance along with laboratory, physician, and population surveys are used
40
o 30
._
-
Q
o
° 20
o
o
A
a)
' 1 0
o
\CA GA MD
CT TN OR
U.S. States
MN TX / Toronto,
Canada
FIGURE 3-2 Incidence of Streptococcus pneumonias disease, by state, July 1995 to
June 1996. SOURCE: Cetron et al., 1997.
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48
40
o
~ 30
3
Q
o
Q
lo
lo
° 20
lo
a)
Q
Oh
10
o
PUBLIC HEALTH SYSTEMS AND EMERGING INFECTIONS
Penicillin resistant
Penicillin intermediate
· Penicillin susceptible
1: :~:~:~
\CA GA MD CT
1 ~ ~ ~ ~ ~ ~ ~
__
-
-
_ -
TN OR MN TX Toronto,
/ Canada
U.S. States
FIGURE 3-3 Incidence of invasive Streptococcus pneumonias disease by geographic
area and penicillin susceptibility. SOURCE: Cetron et al., 1997.
together to obtain estimates of the foodborne disease burden. For example,
Campylobacter is the most common of the bacterial foodborne pathogens in
FoodNet in this surveillance, followed by Salmonella and Shigella.
Population-based surveillance reveals seasonal, geographic, and demo-
graphic variations in foodborne diseases. For example, in the San Francisco Bay
area, where the rates of foodborne illnesses caused by Campylobacter are the
highest, rates of illness are much higher among Latino and Asian children than
among other groups. This has prompted a case-control study of the risk factors
for foodborne Campylobacter infections3 in Latino and Chinese-American chil-
dren in the California EIP.
Surveillance for Campylobacter infections has also enabled a focused look
at quinolone resistance in Minnesota. The proportion of C. jejuni isolates resis-
tant to nalidixic acid increased over time. These infections occur in persons with
a history of foreign travel, reflecting foreign exposure to resistant organisms.
Increasingly, however, resistance is being observed among domestically ac-
quired cases. This provides another example of how population-based surveil-
lance data are enhanced by a focused look at an important public health phe-
nomenon.
3Infections refer to the entry and development of an infectious agent in the body of a
person or animal. In an apparent, "manifest" infection, the infected person outwardly
appears to be sick. In an unapparent infection, there is no outward sign that an infectious
agent has entered the person at all. Infection should not be confused with disease.
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SUR VEILLANCE
49
The highest incidence of Escherichia cold 0157:H7 infection has also oc-
curred in Minnesota. However, an EIP network-wide survey on physician
knowledge of laboratory practices showed that physicians in Minnesota were
more knowledgeable about whether their laboratories routinely cultured clinical
specimens for E. cold 0157:H7. They were also more likely than physicians at
other sites to have actually obtained a sample for E. cold 0157:H7 culture from
their last patient with bloody diarrhea, suggesting that at least some of this ap-
parent difference in incidence may be attributable to variations in practice.
Recent changes in the epidemiology of bacterial meningitis in the United
States have resulted from the decline to very low levels of Haemophilus influen-
zue type b (Hib) due to the licensing and use of effective conjugate vaccines. At
the same time, however, Group B streptococcal infections have emerged as an
important cause of neonatal meningitis and sepsis in the United States;they are
responsible for an estimated 7,500 cases of sepsis4 and meningitisS annually
among newborns with direct costs of $300 million. Accordingly, the EIP net-
work has been using active, population-based surveillance to track the incidence
of this disease, and also to gauge the uptake and impact of Group B streptococ-
cal infection prevention policies.
In 1996, CDC, together with the Academy of Pediatrics and the College of
Obstetricians and Gynecologists, developed consensus guidelines for the pre-
vention of Group B streptococcal disease. These guidelines included late prena-
tal screening to identify Group B streptococcus carriers, intrapartum prophylaxis
of preterm deliveries and carriers, and empiric prophylaxis based on risk factors
for Group B streptococcus disease at labor. Surveillance data later showed a
decline in the incidence of neonatal Group B streptococcal infection, but only in
the incidence of disease with onset early in life. This is essentially what would
be predicted if preventive policies were in place (see Figure 3-41.
Additional data indicate that hospitals with no Group B streptococcal pre-
vention policy had little or no decrease in the mean number of cases of Group B
streptococcus infection between 1996 and 1997, but hospitals that adopted or
revised a Group B streptococcus prevention policy in 1996 saw a significant
decline in the number of early onset cases of Group B streptococcal infection
(see Table 3-1~.
In conclusion, the EIP Network has been a valuable component in the im-
plementation of CDC's plan to address emerging infections by emphasizing
population-based active surveillance and collaboration among CDC and partners
in the public health and academic communities.
4Sepsis is the presence of pathogenic microorganisms or their toxins in blood or
other tissues.
Meningitis is an inflammation of the membranes surronding the brain and spinal
cord. People sometimes refer to it as spinal meningitis. Meningitis is usually caused by a
viral or bacterial infection.
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50
lo, 30
Al
._
._
~ 20
Q
in
LL
in
Cal
._
in
o
I
o
o
A
PUBLIC HEALTH SYSTEMS AND EMERGING INFECTIONS
25
t5
10
CDC Consensus
Guidelines Issued
...
1
5 L 1~ ~ ~ ~ ~
:
1993 1994 1995
Year
1996 1 997
2
u'
1.5 (D
co
-
o
Lo
to
CD
w
0.5 ~
s
u'
O
FIGURE 3-4 Number of hospitals in California, Georgia, Maryland, and Tennessee
establishing Group B streptococcus prevention policies and the incidence of early-onset
Group B streptococcal disease by year, based on active surveillance. SOURCE: Adapted
Tom Rosenstein et al., 1997.
LARGE NATIONAL COMMERCIAL LABORATORIES
Linda Miller, Ph.D.
Assistant Director, Clinical Microbiology, SmithKline Beecham
Private companies, such as SmithKline Beecham Pharmaceuticals, have an
interest in antimicrobial agents and vaccines. To pursue these interests, antimi-
crobial susceptibility surveillance studies are conducted to determine the per-
centage of organisms that are susceptible to different antimicrobial agents
Large commercial laboratories have several reasons to pursue surveillance:
(1) quality assurance, (2) as a service to customers (e.g., for respiratory infec-
tions, data on susceptibility could affect empiric therapy) (3) compliance with
federal regulatory agencies through the provision of data on reportable diseases,
(4) as a service to current public health, and (5) product development.
In 1993, the FDA requested that pharmaceutical companies gather and
submit in vitro susceptibility data for organisms that were listed on the product
information label (package insert available for prescription drugs). As a result,
pharmaceutical companies have an interest in gathering in vitro susceptibility
data on organisms. In addition, the pharmaceutical industry conducts antimicro-
bial surveillance to demonstrate the activity of a drug in comparison with those
of other agents.
Such surveillance studies usually include isolates from community-acquired
or hospital-based infections. These studies are conducted to track rates of resis-
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SUR VEILLANCE
51
lance, in part to ensure that the drug maintains its activity so that the organism
can remain on the product labeling.
For drugs that are in development, surveillance is also critical as an adjunct
to or in support of clinical Dials. Some clinical studies are required to establish
that a drug has efficacy against resistant pathogens, which is difficult if the rates
of resistance are low. Moreover, because of the study design, a majority of iso-
lates from the patients in the clinical study may not be highly resistant, requiring
supplemental in vitro studies.
Traditional surveillance entails large-scale studies over a wide geographic
region to collect isolates for susceptibility testing. Targeted surveillance in-
volves searching for geographic areas where isolates are resistant. This Wpe of
surveillance is useful when developing novel antimicrobial agents. Molecular or
genetic-based studies are also used for surveillance. Finally, existing databases,
such as those created through routine susceptibility testing, provide another op-
portunity for surveillance.
The Sm~thKline Beecham Clinical Laboratones (now Quest Laboratones) are
among the largest clinical laboratories in the United States, with more than 80,000
physicians, hospitals, and corporate clients and more than 100 million tests proc-
essed annually. One of its efforts is Project Beta-Alert, a Haemophilus study that
aims to determine the percentage of beta-lactamase-producing Haemophilus influ-
enzae swains among the H. influence isolates sent to the large commercial refer-
ence laboratory. The project includes isolates Tom most states. As part of the rou-
tine daily work, a technologist isolates the organism, identifies it as H. influenzas,
arid performs the beta-lactamase test. The data can be tracked to a zip code. Data
Tom 1997, sorted by specimen source, patient age, month of collection, laboratory
site, state, and zip code, suggest that for empiric therapy, 3 in 10 patients require
treatment with a drug resistant to beta lactamase activity. Data collected Tom 1993
to 1997 for 44,691 Haemophilus isolates showed that 35 percent produced a beta-
TABLE 3-1, Early-Onset Group B Streptococcus (GBS) in Hospitals with
and Without Prevention Policies in 1996
Mean No. of
GBS Cases
No. of Mean No. of
GBS Policyin 1996 Hospitals Births, 1996 1996 1997 p value
None 66 1,720 1.32 1.09 0.26
Any new or revised 45 1,672 1.29 0.58 0.006
policy
NOTE: Hospitals with policies had a significant decline in cases.
SOURCE: Adapted from Factor et al., in press.
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PUBLIC HEALTH SYSTEMS AND EMERGING INFECTIONS
lactamase, with the highest percentage of isolates being Tom children under age 6.
Another study conducted in 1997 and 1998 involved collection of 2,000 isolates
each of Streptococcus pneumonias and H. influenzas. Isolates were collected from
SmithKline Beecham laboratory sites in all regions of the United States and were
sent to a central laboratory for testing. For S. pneumonias, the highest rate of peni-
cillin resistance was found among isolates in samples from the south-central and
southeast regions of the United States. Macrolide resistance was also highest
among isolates in samples from the south central and southeast regions of the
United States. The surveillance data also showed rates of penicillin resistance in S.
pneumonias by site of infection, with the ear and sinus isolates having the highest
rates of penicillin resistance. Data on age distribution revealed that the vast major-
ity of the drug-resistant S. pneumonias and Haemophilus isolates were found in
young children less than 2 years of age.
Examples of other large surveillance projects in the planning stage include a
pneumococcal surveillance project, the development of a national database on
gram-positive and gram-negative organisms, and surveillance for drug resistance
among Mycobacterium tuberculosis strains. Studies that attempt to correlate
antimicrobial agent use with antimicrobial agent resistance, a relationship that is
difficult to establish, are also being considered.
.
Some companies provide in vitro data from an on-line surveillance network,
which connects hospitals with company computers on a nightly basis. Data on
all the organism identifications and the results of susceptibility testing are col-
lected. However, because samples come from many states and states vary in
their reporting practices, data collection can be arduous. In addition, a net-
worked system between the private and public sectors requires a certain level of
data standardization. This type of routine data collection is an invaluable re-
source in retrospective analyses for surveillance purposes.
Any large-scale private surveillance effort must guard against violation of
patient privacy as well as breach of proprietary concerns. Because diseases cross
borders, such commercial work must also contend with international issues.
Moreover, large-scale surveillance is expensive and profit margins are slim for
commercial clinical laboratories. Given these limitations, it will be increasingly
important for the public and private sectors to arrange collaborative surveillance
projects on matters of widespread public health consequence.
ROLE OF THE PUBLIC-SECTOR LABORATORY AT
THE NATIONAL LEVEL
Joe McDade, Ph.D.
Deputy Director, National Centerfor Infectious Diseases,
Centers for Disease Control and Prevention
In 1988, IOM defined public health as what society does collectively to en-
sure the conditions in which people can be healthy (IOM, 1988~. The core func-
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53
lions of public health are assessment, policy development, and assurance. Ac-
tivities performed by the public health sector include the following:
population-based disease surveillance;
epidemiological investigations;
. environmental assessments of food, water, and vectors;
ensuring the quality of public-and private-sector laboratory testing;
tracking incipient trends;
. conducting outbreakinvestigations;
tracking the distribution and the migration of noteworthy pathogens; and
. monitoring the effectiveness of prevention programs.
CDC laboratories make a unique contribution to reference diagnostic or
confirmatory testing. CDC also plays a pivotal role in gathering, collating, and
analyzing data from multiple sources. For example, reports of deaths due to
pneumonia and influenza come to CDC from many sources: state health depart-
ments, physicians, and a World Health Organization network comprising 110
different laboratories, in 83 different countries, that obtain isolates and use rea-
gents and materials provided by CDC to determine the influenza virus type.
CDC can further subtype isolates submitted to it by using molecular sequencing.
All these efforts ensure relevance of the influenza vaccines produced every year.
Another example of a key role of a national laboratory, such as CDC's Na-
tional Center for Infectious Diseases, is in the characterization of various mea-
sles virus isolates to determine if prevention efforts have stopped the indigenous
transmission of measles. To conduct this work, isolates were obtained through-
out the world and were then sequenced for determination of their genotypes. It
was found that certain measles viruses are peculiar to certain areas of the world
and that transmission is indigenous in those countries. The data also showed that
a measles vaccination program had been effective in interrupting transmission of
the measles virus in the United States and that the existing vaccine offered pro-
tection against those isolates reported from outside the United States.
CDC and other laboratories also serve as international reference laboratories
for determination of whether polio virus types 1, 2, and 3 are being transmitted
and whether polio virus infections are caused by wild-type strains or break-
throughs of the attenuated vaccine strain. Such information is crucial in im~nuni-
zation efforts.
Despite the strengths of the public-sector national laboratories, there is a
need for collaboration with private-sector facilities in the standardization of da-
tabases and the evaluation of reagents and techniques. Such collaborations will
be particularly important because cost-containment efforts and changes in the
ways in which health care is administered may compromise disease surveillance
efforts. For example, under managed care, there is a disincentive to collect iso-
lates and specimens for cultures on which laboratory surveillance is based. In
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PUBLIC HEALTH SYSTEMS AND EMERGING INFECTIONS
certain instances, the commercial laboratory system has supported the state pub-
lic health laboratories when high-volume testing has been needed for tests for
rare and unusual diseases. In contrast, public health laboratories are more suited
to performing specialized testing.
In the absence of a well-def~ned national laboratory system, more strategic
planning is needed. This would entail, for example, defining the surveillance and
information needs for specific diseases, the type of testing needed, the materials
and specimens required, the roles of the public and private sectors, and the refer-
ral systems and core capabilities, as well as standardizing methods and databases.
ROLE OF THE PUBLIC-SECTOR LABORATORY AT
THE STATE LEVEL
Mary Gilchrist, Ph.D.
Director, University of Iowa Hygienic Laboratory
Most state public health laboratories were instituted in the early part of the
2Qth century, when they were nearly the sole source of expertise and training in
public health and when a microscope might have been the primary tool available
for diagnosis of a disease. By mid-century there was a decline in the rate of in-
fectious diseases and a rise in local laboratory expertise, which led to more focus
at the state level on diseases of traditional public health importance such as tu-
berculosis, syphilis, and rabies and on specialized reference bacteriology and
virology.
By the 1970s another type of state public health facility, the combined or
consolidated laboratory, emerged when the U.S Environmental Protection
Agency was instituted and some public health laboratories expanded to include
environmental testing. A third type of laboratory, the consolidated laboratory,
performs still other services for the state in the areas of agriculture, forensics,
and some newborn screening.
By the mid-199Os, with the inception of the emerging infections program,
CDC's new cooperative agreements with states created new opportunities and
challenges for state laboratories. They began expanded activities such as typing
of Mycobacterium tuberculosis, Escherichia cold 0157, and Salmonella isolates
and characterization of antibiotic resistance. New molecular techniques such as
these have established critical new roles for public health laboratories.
Most public health laboratories have routine surveillance programs for in-
fectious agents of significance in their regions. Outbreaks are then detected ear-
lier and are defined more clearly.
An example of an active state surveillance program is Iowa's influenza vi-
rus surveillance activities. At the state laboratory the influenza virus is isolated,
identified, and typed before being sent to CDC as part of the World Health Or-
ganization surveillance system that tracks disease and predicts vaccine needs.
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55
The state laboratory automatically posts nightly on the Internet (http://www.uhl.
uiowa.edu) all of the influenza virus isolates in its database. Thus, real-time data
on the geographic incidence of various influenza virus types and the number of
isolates that have been detected in each of the state's regions throughout the
winter season are available. In the future, the system will offer quicker detection
of more viral agents. It will also provide hypertext links to information on vac-
cines and antiviral therapies. Thus, if a clinician wants to know whether the cur-
rent vaccine is effective against a given circulating strain, a query to the website
will provide that information.
The public health laboratory in Iowa also conducts vector-borne disease
surveillance. For example, it monitors sentinel chicken flocks for the presence of
antibodies to arboviruses and examines pools of mosquitoes for the presence of
arboviruses, enabling cities and counties to control mosquitoes before encepha-
litis6 viruses cause a substantial risk to humans. Surveillance for the emergence
of tick-borne infections is also conducted in Iowa. Deer hunters send in samples
of deer blood on filter paper for studies of the distribution of antibodies against
the Lyme disease spirochete and the agents of ehrlichiosis. Surveillance for
vector-borne diseases has shown how these pathogens are emerging in Iowa
along the Mississippi River through animals that are migrating up the river val-
leys. As a result, public health laboratories can alert health care practitioners
about the prevalence of new infectious agents in Iowa.
In collaboration with the University of Iowa, the state Hygienic Laboratory
conducts an antibiotic resistance surveillance program, looking for organisms that
cause invasive diseases: enterococci, Streptococcus prze?~moniae, methicillin-
resistant Staphylococcus aureus, vancomycin-intermediate or -resistant staphylo-
cocci, and Group A streptococci. The University of Iowa conducts the suscepti-
bility testing, and the Hygienic Laboratory codes and serotypes the isolates. The
data are available on the Intemet so a health care practitioner can check on the
prevalence of resistance in the area of the state where the patient resides.
Iowa is also planning a program that will detect infectious agents that could
be released as a result of terrorism. Because such an attack is likely to result in
the dispersal of infection in isolated settings throughout the country, the state
public health facility is likely to be involved. In the various scenarios contem-
plated the need for adequate reporting and recognition by the attending physi-
cian are paramount for surveillance. For example, if a physician does not re-
member that anthrax is caused by a Bacillus species and does not notice that the
laboratory reported it as a bacterial contaminant, he or she might not immedi-
ately attribute a death to anthrax. The cause of the disease might not be detected
until later, when reports of a mysterious illness surface around the country. In
some cases, the laboratory might presume that the isolate is a member of the
6Encephalitis is an acute inflammatory disease of the brain due to direct viral inva-
sion or to hypersensitivity initiated by a virus or other foreign protein.
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PUBLIC HEALTH SYSTEMS AND EMERGING INFECTIONS
patient's normal flora and it is not until the isolate is referred to a central refer-
ence laboratory, possibly 2 weeks later, that the agent released by bioterrorists
would be identified.
Identifying and reporting such agents are shared responsibilities of a na-
tional laboratory network of state facilities and local laboratories. In this regard,
the Internet will serve as an invaluable tool for the sharing of information. In
addition, what is needed is rapid communication, combined with algorithms for
pathogen and disease identification, protocols for safety, a national laboratory
training network, and the ability to detect multi-state outbreaks in real time. The
Association of Public Health Laboratories recommends the formation of such a
national network. State laboratories, because of their environmental chemical
expertise, could augment the network by providing a means of detection of the
agents of chemical terrorism. Preparation of state and private laboratories for
bioterrorism events will enhance the ability to detect infectious diseases that
emerge naturally.
Representative terms from entire chapter:
health laboratories
