Surveillance

Surveillance is a core function of public health, tracking trends, guiding prevention strategies, and detecting outbreaks. We conduct national surveillance for major bacterial infections transmitted through food or water, and for outbreaks of foodborne infections of any cause. We develop and implement better tools for public health surveillance.

PulseNet, our new network for DNA "fingerprinting" of bacteria that cause foodborne illness, links state public health laboratories, CDC and the food regulatory agencies together so that multistate outbreaks can be rapidly detected and investigated. PulseNet technology provides each state with the capacity to detect clusters of infections. In Fiscal Year (FY) 2004, PulseNet included all 50 states and Canada, covering Listeria, Shigella, E. coli O157:H7 and Salmonella. PulseNet China launched, and the international networks of PulseNet Europe, Asia Pacific and Latin America held formative meetings.

Also in FY2004, our electronic foodborne outbreak reporting system (eFORS) gathered reports of more than 1000 such outbreaks. In addition to routine national surveillance of reportable infections such as salmonellosis and shigellosis, the FoodNet program conducts active surveillance for a broader range of pathogens in a group of sentinel sites, providing reliable and accurate information on the incidence of and risk factors for a variety of foodborne infections. FoodNet is our collaborative effort among ten states, the food regulatory agencies, and CDC’s Emerging Infectious Disease Program. In FY2004, FoodNet documented a continuing decline in the incidence of Campylobacter and Salmonella and the first significant decrease in E. coli O157:H7 infections since FoodNet began in 1996. Our collaborative monitoring program for antibiotic resistance in foodborne organisms documented continuing resistance in Salmonella to ceftriaxone and in Campylobacter to fluoroquinolones, the drugs of choice for treating severe intestinal infections.

Outbreaks

An outbreak of infections occurs when a group of people develop the same illness after a common exposure. We investigate outbreaks to identify the illness and the exposure, to control the outbreak and to learn how to prevent future similar outbreaks. Most outbreaks are investigated by local or state health department epidemiologists. We provide emergency support for state health departments and the World Health Organization (WHO).

In FY2004, we conducted ten emergency outbreak field investigations and consulted on many more. We conducted two major investigations of Roma tomato-associated salmonellosis tracked to Florida that stimulated new research into how such contamination might occur. A large outbreak of Campylobacter infections from a resort island in Ohio stimulated revision of the local water supply and discussion about the safety of "private" water sources used by the public.

We investigated a major outbreak of multiple-resistant (resistant to more than one antibiotic) salmonellosis in the Northeast, which is stimulating additional regulatory and industry dialogue about how to make our ground beef safer. We investigated an epidemic of cholera in Zambia, showing that fresh produce from the flooded market was the main source; this investigation is the poster child of the WHO "Healthy Market" initiative.

We also led the CDC response to the Tsunami disaster in Southeast Asia, and participated in the disaster response to hurricane flooding in Haiti, using the CDC Safe Water System in both disasters.

Public Health Tools and Prevention

Through applied research, we improve public health tools and increase the scientific basis for prevention. In FY2004, we continued the multi year international effort to develop new molecular tools for subtyping Salmonella and Campylobacter, harnessing the latest DNA methodologies to the practical problem of characterizing these complicated organisms.

We aim to replace traditional serotyping with a molecular equivalent and to develop an improved strategy for subtyping that can eventually replace pulsed field gel electrophoresis in PulseNet. We characterized new molecular loci of antimicrobial resistance in Salmonella and Campylobacter.

We continued the commercialization of a new rapid and sensitive ELISA test for detecting botulism toxin. The FoodNet study of Campylobacter infections linked these to eating undercooked poultry, particularly in restaurants, and linked poultry consumption and foreign travel with fluoroquinolone-resistant Campylobacter infections. These data were used by the FDA to propose a withdrawal of approval of fluoroquinolone for poultry.

Our CDC Safe Water program enables communities in the developing world to make their drinking water safe. In FY2004 in Kenya, we found that this program reduced diarrheal illness by 50%. Because simple chlorination is less effective in murky water, we developed a new product with Procter and Gamble that both clarifies and disinfects drinking water. In FY2004, we showed that this product was effective in reducing disease in Kenya and Bangladesh. We published a major study showing that hand washing with soap reduced diarrheal illness by more than 40% in Pakistani children.

Training and Reporting

We expand our impact by training public health personnel around the world, and by publishing scientific reports. In FY2004, we conducted five training courses for microbiologists in serotyping methods for Salmonella. We trained five Epidemic Intelligence Service (EIS) officers in epidemiology and public health, and selected one international WHO food safety fellow who will join us this year.

We also developed a course on foodborne disease epidemiology for use in international settings. The CDC Safe Water field manual was published in French and Spanish.Finally, we shared our most recent findings with the scientific community and the public at large in the form of 93 scientific reports and papers, and a great number of lectures and posters.

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