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| Bureau of Epidemiology | October 1999 | Utah Department of Health | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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FoodNet
— Active Surveillance of Foodborne Diseases
FoodNet is
the foodborne disease component of the Centers for Disease Control
and Prevention’s (CDC’s) Emerging Infections Programs
(EIP). It is a sentinel network that uses data from active surveillance
plus additional studies to produce more accurate national estimates
of the burden and sources of specific foodborne diseases in
the United States. The objectives of FoodNet are to determine
the frequency and severity of foodborne diseases; determine
the proportions of common foodborne diseases that result from
eating specific foods; and describe the epidemiology of new
and emerging bacterial, parasitic, and viral foodborne pathogens.
Population-based active surveillance was conducted during 1998 for confirmed cases of Campylobacter, Cryptosporidium, Cyclospora, Shiga toxin-producing Escherichia coli O157, Listeria, Salmonella, Shigella, Vibrio, and Yersinia infections in Connecticut, Minnesota, and Oregon and selected counties in California, Georgia, Maryland, and New York. In 1998, nearly 10,000 confirmed cases of the diseases under surveillance were identified in the seven sites. Most of the pathogens were bacterial; however, parasitic diseases were reported including Cryptosporidium and Cyclospora. One of the projects’ key findings was that overall incidence rates of the pathogens under surveillance declined. The most dramatic decline was in Campylobacter followed by Salmonella. Utah also showed a decrease in Campylobacter cases in 1998; however, Salmonella infections in Utah increased 14 percent over 1997 rates. In the seven sites, Campylobacter accounted for nearly 50 percent of foodborne bacterial pathogens isolated, far exceeding Salmonella and Shigella, and nearly 10 times greater than E.coli O157:H7 or Cryptosporidium. Yersinia, Listeria, and Vibrio infections trailed the pack. In Utah, Salmonella rates are nearly double the Campylobacter rates, four times the E. coli O157:H7 rates, and eight times the Shigella rates. Few confirmed cases of Cryptosporidium, Yersinia, Listeria, and Vibrio have been reported in recent years. Data collected through FoodNet demonstrated that eating chicken and undercooked eggs is associated with Salmonella enteritidis (SE) and Salmonella heidelberg infections. A recent outbreak of SE in Utah was associated with the substitution of shelled eggs for pasteurized egg product in an ice cream recipe. The number of confirmed SE cases has remained high in 1999, and the majority of cases are believed to be associated with the consumption of raw or undercooked eggs. Data extrapolated from the FoodNet surveillance model suggest that there are approximately 1.4 million Salmonella cases in the United States annually, resulting in 113,000 office visits and 37,000 culture-confirmed cases per year. These culture-confirmed cases alone result in nearly 8,500 hospitalizations and 300 deaths. Additional hospitalizations and deaths likely occur among people who do not have culture-confirmed disease. FoodNet surveillance also identified a sustained increase in Vibrio rates that correlated with multistate outbreaks of Vibrio parahemolyticus in 1997 and 1998. Utah had four cases reported in 1997, no cases in 1998, and two cases so far in 1999. The Utah cases were found to be associated with the consumption of shellfish. Another key finding of the CDC’s project was that the rate of E. coli O157:H7 infection increased in 1998 to slightly above the 1996 levels, whereas in 1997 the rate had declined. Utah has seen an increase in E coli O157:H7 rates over those three years. However, the 1999 rate is approximately half of the 1998 rate to date. A 1997 case-control study conducted at the FoodNet sites found that the principle source of E. coli O157:H7 infection is from eating undercooked ground beef. FoodNet also demonstrated that the pathogen associated with the highest fatality rate was Listeria, a rare foodborne disease. Twelve percent of those infected with the pathogen died, resulting in 50 percent of the deaths associated with the diseases under surveillance. Utah had no Listeria cases reported in 1997 or 1998. However, in August 1999, three cases were reported within a 24-hour period with a fourth following shortly thereafter. This prompted an immediate investigation. While no common source of infection was found, two cases had the same PFGE pattern identified in their Listeria isolates. The future activities of FoodNet include continuing its population-based surveillance, expanding the population under surveillance, and piloting an electronic reporting system for outbreaks. Activities will also include repeating a survey of microbiology laboratories at FoodNet sites to determine changes in laboratory practices and repeating a survey of the general population in the catchment area to help determine the burden of foodborne illness in the community. Prevention and Treatment of Influenza Infection The influenza virus is responsible for annual epidemics throughout the world. The viruses are continuously evolving (a process known as antigenic drift) and people who are infected by one strain do not necessarily develop antibodies to protect them from other strains. Also, major evolutionary changes in the virus can and do occur, albeit, rarely (a process known as antigenic shift). When these major changes happen, the results can be disastrous. Virtually everyone is 100% susceptible to the new strain, and if the strain is particularly virulent, a pandemic can occur.Vaccination, currently the best method for preventing influenza, is effective when there is an antigenic match between the circulating strains and the strains contained in the vaccine. This is difficult because the virus is constantly changing. The world-wide network for influenza surveillance has grown to include approximately 110 national laboratories in over 80 countries. This serves as a model of international collaboration and permits a rapid exchange of information. The primary objective of this network is to provide data which will allow scientists to match, as closely as possible, the antigenic properties of the influenza vaccine with viral strains that are likely to circulate in the next influenza season. Although vaccination is the primary method for control of influenza, antiviral agents also have a role in the prevention and treatment of influenza infection. Chemoprophylaxis with antiviral agents may be considered during community outbreaks for the following groups:
The development of antibodies in adults after vaccination can take as long as two weeks, during which time chemoprophylaxis may be considered in the event of an outbreak. Children who receive influenza vaccine for the first time can require as long as six weeks to develop antibodies. In the event of the rapid spread of a new influenza virus, antiviral agents could play a major part in protecting persons at high risk or even the general community while specific vaccines are being developed. In addition, antiviral agents can reduce the severity and shorten the duration of illness among healthy adults when administered within 48 hours of illness onset. When confirmed or suspected outbreaks of influenza occur in institutions that house persons at high risk, chemoprophylaxis should be started as early as possible to reduce the spread of the virus. Such facilities need contingency planning to ensure rapid administration of antiviral agents to residents. This planning should include preapproved medication orders or plans to obtain physicians’ orders on short notice. When antiviral agents are used for outbreak control, the drug should be administered to all residents of the institution, regardless of whether they received influenza vaccine. Chemoprophylaxis may also be considered for controlling influenza outbreaks in other closed settings such as dormitories or other settings where persons live in close proximity. The most common antiviral agents for the prevention and control of influenza are amantadine and rimantadine. They are chemically related drugs that interfere with the replication cycle of influenza type A viruses. They are not effective against influenza type B. A new class of antiviral agents has been developed that inhibit influenza neuraminidase. These agents reduce the replication of influenza A and B viruses and have been approved for influenza treatment. One is Relenza® (zanamivir), an inhaled antiviral drug, and the other is Tamiflu® (oseltamivir phosphate), an oral antiviral drug. The following table provides information on these antiviral agents.
Is the Food That You Prepare in Your Home Safe? Holiday Turkey Tips
Utah Department of Health, Bureau of Epidemiology Monthly Morbidity Summary - October 1999 - Provisional Data
Rod Betit, Executive Director,Utah Department of Health
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