[Emerging Infectious Diseases]
[Volume 4 No. 2 / April - June 1998]

News and Notes

The National Food Safety Initiative

For many years, the Centers for Disease Control and Prevention (CDC) and
state and local health departments have investigated and controlled
outbreaks of foodborne diseases and conducted limited passive surveillance
for specific foodborne pathogens. However, recent changes in the food
supply and in the consuming public have changed the type and range of
infections caused by food and have made traditional approaches to disease
surveillance increasingly inadequate. In particular, new technology which
facilitates the national and international distribution of food to a
population of consumers increasingly vulnerable to infection by new
microorganisms has changed the character of foodborne disease in the United
States in ways that demand more and better information for decision making.

Foodborne Disease Surveillance

In 1997, President Clinton announced an administration initiative to create
a nationwide early warning system for foodborne diseases, enhanced food
safety inspection, and expanded food safety research, training, and
education. The National Food Safety Initiative will meet the challenges
presented by the changing nature of our food safety concerns by
strengthening and broadening surveillance and response systems at CDC and
the state and local health departments. The following areas of national
surveillance for foodborne diseases are addressed by the initiative: rapid
identification of and effective response to foodborne hazards;
identification of large, diffuse outbreaks that have a low attack rate
within one health jurisdiction but affect the health of many people within
a larger geographic area; and evaluation of the nature and scope of food
safety problems. In addition, the National Food Safety Initiative will 1)
link CDC, state and local health departments, and other federal agencies
within a powerful electronic network developed by CDC for rapid sharing of
microbial subtyping information, including the digitalized images of
subtyping patterns needed for molecular epidemiology, and 2) will enhance
and expand the activities of FoodNet, the interagency foodborne disease
component of CDC's emerging infectious disease active surveillance program
to improve the quantitative base for foodborne disease.

Strengthening and Broadening the Base of Surveillance

Under the National Food Safety Initiative, CDC is building epidemiologic
and laboratory capacity in state and local health departments so they can
quickly and effectively identify foodborne hazards, investigate and control
outbreaks, and develop effective programs to prevent additional illnesses
from the same source. Routine surveillance and outbreak response, critical
to the proper functioning of health departments, have been neglected at the
state and local levels because of limited resources and competing
priorities. Therefore, CDC is providing training and equipment needed by
the health departments to update surveillance systems and diagnostic
capability for bacterial, parasitic, and viral foodborne diseases. In
addition, CDC, state epidemiologists, and state public health laboratory
directors are working to define the elements of core capacity for effective
response to food safety problems. The results of this evaluation will
provide guideposts for efficient allocation of initiative resources in 1999
and beyond to construct a truly effective national early warning system for
foodborne diseases.

CDC's response to foodborne hepatitis A virus infections, supported in 1998
by the National Food Safety Initiative, illustrates the value of better
surveillance. Existing hepatitis A surveillance data document food as a
vehicle of transmission in only 2% to 5% of cases. On the basis of these
data, economic analysis suggests that routine immunization of food workers
to prevent foodborne transmission of hepatitis A virus (with a vaccine
already available) is not a cost-effective nationwide public health
response. However, existing surveillance data document a source of exposure
(food or otherwise) for only half of the reported cases of hepatitis A.
Therefore, CDC is collaborating with health departments in three states to
more fully describe the epidemiology of hepatitis A infections for which
routine investigation fails to determine a source. In addition, CDC will
evaluate the effectiveness of the algorithm used to determine which patrons
of food service establishments with infected food workers will receive
immune globulin for postexposure prophylaxis and will establish a genetic
sequence-based library of hepatitis A virus strains circulating in the
United States and other countries to permit the effective use of molecular
epidemiology in investigations of hepatitis A outbreaks and sporadic cases.

Diarrheal disease results in large numbers of physician visits and
hospitalizations each year in the United States. However, the infectious
cause of the illness is frequently not determined, which prevents good
surveillance and impedes development of effective prevention strategies.
Therefore, CDC is embarking on studies of mild and severe diarrhea to
determine to the greatest extent possible the bacterial, parasitic, and
viral agents involved. Similarly, applied research at CDC that is improving
diagnostic and subtyping methods for parasitic foodborne diseases and
caliciviruses will support future surveillance and outbreak response for
these foodborne pathogens, as well as help define the extent of their
contribution as causes of sporadic foodborne disease.

Establishing Electronic Networks and Generating Quantitative Data

Another aspect of CDC's response to foodborne disease under the National
Food Safety Initiative is the development of an electronic network that
links public health laboratories for rapid data sharing, including the
digitalized images of pulsed-field gel electrophoresis (PFGE) patterns.
These patterns can be used to distinguish related cases that may be part of
an outbreak from background disease so that risk factors can be identified
and control measures can be established. By the end of 1997, CDC had
laboratories in 16 state health departments trained and equipped to perform
PFGE subtyping of Escherichia coli serotype O157:H7 with standardized
techniques so the results could be compared among laboratories.
Microbiologists in federal regulatory laboratories were also trained in
these standardized techniques so E. coli O157:H7 isolated from food and
animal samples could be directly compared with clinical isolates from human
cases. Laboratories in four states were established as regional resources
to make PFGE subtyping available to surrounding states, and one was
directly linked to CDC's PFGE library of strains so it could query CDC's
database in addition to being able to submit electronic data for analysis.
The other three regional laboratories and laboratories in USDA and FDA will
be directly linked to CDC's database early in 1998; the remaining six
FoodNet sites will be linked later in the year. In addition, in 1998 six
more states will be trained and equipped to perform PFGE subtyping of E.
coli O157:H7, training will be provided to health department laboratories
in two foreign countries, PFGE subtyping of Salmonella Typhimurium will
begin, and methods for subtyping Salmonella Enteritidis and other foodborne
pathogens will be developed.

Changes in food safety regulations (e.g., regulatory use of Hazard Analysis
and Critical Control Points systems and international requirements for
quantitative risk assessment) and increasing emphasis on the
cost-effectiveness of prevention programs require epidemiologic data on
foodborne disease that cannot be provided by routine passive surveillance
systems based on laboratory and physician diagnoses. In response, CDC
collaborated with U.S. Department of Agriculgure, Federal Drug
Administration, and the five state health departments enrolled in CDC's
emerging infections active surveillance program in 1995 to create FoodNet.
FoodNet expands the quantitative database on foodborne diseases, expedites
response to certain food safety concerns, and provides a test bed for
evaluating new prevention strategies. FoodNet activities include 1)
comprehensive documentation of foodborne infections through active
laboratory-based surveillance, 2) determination of health and food-handling
practices of the population under surveillance, 3) determination of
health-care practices by surveys of the physicians and diagnostic
laboratories in the surveillance areas, and 4) implication of specific
foods as vehicles for various foodborne pathogens by conducting
case-control studies of sporadic infections.

These efforts have shown that Campylobacter is the most commonly diagnosed
cause of diarrheal disease, that great geographic variations in the
frequency of E. coli O157:H7 infections and other foodborne pathogens
suggest a need for targeted control measures, and that approximately 1.4
diarrheal illness episodes occur per person per year in the United States.

FoodNet began with active surveillance of sporadic infections with seven
bacterial pathogens in the five sites. In 1997, two new sites were added,
and in 1998 an eighth active surveillance site will be added; active
surveillance for Cryptosporidium, Cyclospora, and Calicivirus infections
will be included, and intensive investigation of foodborne disease
outbreaks will be initiated. Many bacterial pathogens, including those that
are foodborne, are becoming resistant to antibiotics. To measure this
change in resistance, CDC, in collaboration with FDA, USDA, and the states,
began monitoring resistance levels of several foodborne bacteria. This
information is being used to promote the prudent use of antibiotics in
human health and in agriculture.

Other Food Safety Initiative Projects

In 1999, in addition to continuing and extending surveillance activities,
CDC plans to support the following projects through the National Food
Safety Initiative: school-based health education to teach foodborne disease
prevention to a new generation of consumers; a foodborne disease diagnosis
and surveillance component to CDC's Field Epidemiology Training Program,
which helps Ministries of Health in foreign countries (many of which are
major food exporters to the United States) improve their surveillance and
diagnostic capabilities; and new methods of determining the risk for
exposure to pesticide residues in food. The National Food Safety Initiative
is building the public health framework for an effective and efficient
response when novel foods from new areas that contain unfamiliar foodborne
hazards are introduced into the marketplace.

Sue Binder, Rima Khabbaz, Bala Swaminathan, Robert Tauxe, and Morris Potter

Centers for Disease Control and Prevention, Atlanta, Georgia, USA

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Meeting Summary

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Conference on Global Disease Elimination and Eradication as Public Health
Strategies, February 26, 1998

The goals of the conference were to assess the role of elimination and
eradication in decreasing global disease and in using health resources more
effectively. Two hundred invited representatives from 81 organizations and
34 countries participated in the multidisciplinary conference; the
proceedings will be published in late 1998 in a supplement to the Bulletin
of the World Health Organization.

The working definitions during the conference were those developed at the
Dahlem Workshop on the Eradication of Infectious Diseases, March 1997.
Disease control: reduction of disease incidence, prevalence, illness, or
death to a locally acceptable level as a result of deliberate efforts;
continued intervention measures are required to maintain the reduction.
Disease elimination: reduction to zero of the incidence of a specific
disease in a defined geographic area as a result of deliberate efforts;
continued intervention measures are required. Disease eradication:
permanent reduction to zero of the worldwide incidence of infection caused
by a specific agent as a result of deliberate efforts; intervention
measures are no longer needed.

The successful smallpox program and the ongoing poliomyelitis and
dracunculiasis (Guinea worm disease) programs served as models in the
discussions on eradication. The malaria, yellow fever, and yaws programs of
earlier years were recognized as unsuccessful but to have contributed to
better understanding of the biologic, social, political, and financial
complexities and responsibilities of disease eradication. The conference
addressed five major areas: sustainable development, noncommunicable
diseases, bacterial diseases, parasitic diseases, and viral diseases. The
following is a summary of the conclusions.

Sustainable Development

Eradication programs should have two objectives: 1) eradication of the
disease and 2) strengthening and further development of health systems,
especially functions such as monitoring and surveillance, supervision, and
program management. Potential risks of eradication to the health system and
health development include the diversion of resources from basic services
and other priorities in countries where the disease being eradicated is
perceived to be of lower priority. An additional concern is the failure to
accurately estimate the human and financial needs of the eradication
efforts. Potential benefits for health development should be identified and
delineated at the start of any eradication initiative. Measurable targets
should be set, and the program should be held accountable for achieving
them. Resources for eradication activities should be supplementary to those
available for basic health-care services.

Successful eradication programs are powerful examples of effective
management and can build management capacities that can be carried to other
health programs. Therefore, eradication programs should incorporate efforts
to design program activities that enhance leadership development and
managerial skills among health personnel. These programs also should
actively aid in the development and implementation of surveillance systems
that can be readily adapted to meet the needs of other national priority
programs after eradication goals have been achieved.

Noncommunicable Diseases

The conference concluded that better control was achievable for
micronutrient deficiencies (iodine, vitamin A, iron, and folic acid) and
lead intoxication, even though none of these conditions meet the
requirements for eradication. Recommendations were made for reducing
protein/energy malnutrition and lead intoxication and for accelerating
attainment of global goals for control of micronutrient deficiencies.
Micronutrient supplementation should be enhanced by food fortification and
the opportunities presented by existing health infrastructure and
immunization programs.

Bacterial Diseases

No bacterial diseases were judged to be candidates for eradication within
the next 10 to 15 years. Haemophilus influenzae type b (Hib) and congenital
syphilis are candidates for regional elimination, and trachoma is a
candidate for regional elimination over a somewhat longer term. By the
strict definition, neonatal tetanus elimination cannot be guaranteed,
although the World Health Organization "elimination goal" of <1 case/1,000
live births in every district is attainable.

Eradication was deemed to be a long-term vision for tuberculosis and Hib.
Each of the bacterial diseases considered at the conference represents a
major disease, and each has substantial research needs before long-term
goals can be achieved. Aggressive action was strongly recommended to
improve global control of these conditions.

Parasitic Diseases

The availability of potent, long-acting drugs makes possible the control of
onchocerciasis (river blindness) and lymphatic filariasis on a scale
heretofore unconsidered. Even though no parasitic diseases were candidates
for eradication within the next 10 to 15 years, the group recommended
onchocerciasis as a candidate for elimination. Lymphatic filariasis caused
by Wucheraria bancrofti also could be eliminated and possibly eradicated at
some time in the future.

Filariasis caused by Brugei malayi could be eliminated from many areas, as
could American trypanosomiasis (Chagas disease).

Viral Diseases

The group urged stronger international efforts to control rabies, yellow
fever, and Japanese encephalitis by using existing tools. None of the three
was considered a candidate for eradication. Hepatitis A eradication was
deemed biologically feasible, but further demonstration of sustainable
elimination is a prerequisite.

Rubella and measles were considered possible candidates for eradication
within the next 10 to 15 years. The eradication of rubella as an add-on to
measles eradication was thought biologically plausible, but several issues
first needed to be addressed: the human and financial cost of rubella
disease, the human and marginal costs of adding rubella to a measles
eradication effort, and demonstration that elimination is programmatically
feasible and sustainable in a large geographic area.

Measles eradication was concluded to be biologically plausible with the
present vaccine. In the Americas, measles transmission appears to have been
interrupted for variable time intervals in many countries. Elimination has
yet to be demonstrated in other regional settings. The group recommended
that industrialized countries proceed with elimination of measles as a step
toward eradication. In other countries, accelerating measles control should
be the priority, especially in areas with high death rates. Developing
countries should proceed cautiously to more costly measles elimination
programs to avoid undermining the polio eradication effort. Experience
gained from regional and country interventions should be used to refine the
strategies for eventual eradication.

General Comments

The short list of conditions for elimination and eradication within the
next 10 to 15 years was concluded to be a reflection of current limitations
in our knowledge. Additional basic and operational research was strongly
urged. Some participants expressed concern over the use of the term
"elimination," on the grounds that the distinctions between elimination and
control and elimination and eradication were unclear. Further discussion
and possible revision of these terms were recommended.

In summary, the conference provided a multidisciplinary forum for
addressing issues around elimination and eradication and their relationship
to sustainable health development. There was widespread agreement that an
eradication program could have many positive effects on systems development
and that explicit efforts should be made to maximize these positive effects
as well as to minimize any negative effects. Community mobilization and
organization should be seen as a component of sustainable health
development, with the additional potential for disease control and
eradication. The conclusions and recommendations of the conference should
be brought to other forums to expand international health goals and
strengthen the mutual ties between sustainable health development and
disease control, elimination, and eradication.

For further information, contact Dr. Walter R. Dowdle, 404-371-0466,
e-mail: wdowdle@taskforce.org; or Dr. Richard Goodman, 404-639-7400,
e-mail: rag4@cdc.gov.

Dick Conlon,
Task Force for Child Survival Carter Center, Atlanta, Georgia, USA

Conference sponsors included Burroughs Wellcome Fund; CARE; The Carter
Center; Centers for Disease Control and Prevention (CDC); CDC Foundation;
Children's Vaccine Initiative; The Edna McConnell Clark Foundation; The
Fogarty International Center; Glaxo Wellcome; International Life Sciences
Institute (ILSI); International Union of Microbiological Societies (IUMS);
Merck & Co., Inc. Vaccine Division; National Countil for International
Health (NCIH); National Institute of Allergy and Infectious Diseases
(NIAID); Pan American Health Organization (PAHO); Pasteur Merieux Connaught
USA; The Rockefeller Foundation; Rollins School of Public Health of Emory
University; The Task Force for Child Survival and Development; United
National Children's Fund; United National Development Programme (UNDP); The
World Bank; World Federation of PUblic Health Associations (WFPHA); World
Health Organization; and Wyeth-Lederle Vaccines and Pediatrics.

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New and Reemerging Infectious Diseases: A Clinical Course

Atlanta, Georgia, USA, June 13-15, 1998

Jointly sponsored by the Emory University School of Medicine, Centers for
Disease Control and Prevention, and National Foundation for Infectious
Diseases, New and Reemerging Infectious Diseases: A Clinical Course focuses
on the epidemiology, recognition, treatment, and management of new and
reemerging infectious diseases. The course will bring together the foremost
infectious disease clinicians and epidemiologists to present pertinent
information on emerging infections and prospective therapeutic agents.

For more information, contact Kip Kantelo at NFID, 4733 Bethesda Avenue,
Suite 750, Bethesda, MD 20814-5228, USA, tel: 301-656-0003, fax:
301-907-0878, http://www.nfid.org/nfid, e-mail: kkantelo@aol.com.

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Erratum

Vol. 4, No. 1

In the article, "Emerging Infectious Diseases-Brazil," by Hooman Momen, on
page 3 the last sentence of the next-to-the-last paragraph should read,
"The existing, generally passive epidemiologic surveillance system produces
information that arrives too late to be effective; however, a number of
measures, if implemented immediately, can mitigate the impact of any future
epidemic: a containment laboratory (biosafety level 4) that can handle
known and unknown microbes of high virulence; at least one infirmary,
properly designed and fully equipped, to treat highly contagious and
virulent diseases (the current lack of this facility poses a great danger
to the population should an outbreak of such a disease occur); and a mobile
multidisciplinary task force, including epidemiologists, microbiologists,
entomologists, and clinicians, ready to investigate suspected disease
outbreaks on short notice."


Emerging Infectious Diseases
National Center for Infectious Diseases
Centers for Disease Control and Prevention
Atlanta, GA

URL: http://www.cdc.gov/ncidod/EID/vol4no2/newsnote.htm