STEC O157, Salmonella illness rates down; Campylobacter, Listeria up
By Greg Cima
Posted June 1, 2010
A 10-state surveillance system uncovered fewer illnesses connected with Shiga toxin-producing Escherichia coli O157 in 2009 than in any of the preceding four years.
While the number of Salmonella-related illnesses declined slightly in 2009, compared with the average from 2006 to 2008, the prevalence of confirmed Campylobacter-related illnesses rose slightly, and Listeria-related illnesses rose in the same period, according to preliminary data from the Centers for Disease Control and Prevention. Among those illnesses, only the prevalence of cases connected with STEC O157 is currently low enough to reach a national goal set for the end of 2010.
Baby chicks were among the sources of Salmonella
outbreaks in 2009.
The figures were included in the CDC's April 16 Morbidity and Mortality Weekly Report, which reported preliminary data from the Foodborne Diseases Active Surveillance Network, or FoodNet. The network is part of the CDC's Emerging Infections Program, and the data were collected through surveillance of laboratory-confirmed infections with pathogens that are commonly transmitted through food. The surveillance area includes about 46.4 million people.
Health authorities hope, by the end of 2010, to meet a goal set at the start of the past decade of reducing by half the prevalence of illnesses connected with STEC O157, Salmonella, Campylobacter, and Listeria. The goals are among 467 set through the Department of Health and Human Services' Healthy People 2010 program.
For every 100,000 people in the surveillance area, the CDC received reports of 15.2 confirmed Salmonella infections, 13 Campylobacter infections, 0.99 STEC O157 infections, and 0.34 Listeria infections. While the number of STEC O157 illness was slightly lower than the goal of one confirmed infection for every 100,000 people, CDC officials hoped by 2010 to record no more than 6.8 Salmonella infections, 12.3 Campylobacter infections, and 0.24 Listeria infections per 100,000 people.
The FoodNet data also showed a nearly 40 percent decline in the rate of confirmed Shigella infections.
Barbara Mahon, MD, team lead for the FoodNet and Outbreak Surveillance Team for the CDC, said that, considering the expansion of the surveillance area since the goals were set, the prevalence of Salmonella-related illnesses has slightly but significantly decreased since 2000.
"The fact that we're really not seeing the kinds of decreases that we hoped to see really speaks to the need for new approaches to decreasing salmonellosis," Dr. Mahon said.
Because Salmonella strains are found in the intestines of a wide variety of animals, the variety of food- and non-food-related means of transmission make it difficult to combat illnesses caused by the bacteria, she said. She noted that health authorities are discovering new sources of salmonellosis, such as the pet frogs and pet baby chicks connected with outbreaks during 2009.
Dr. Mahon found it encouraging to see sustained declines in illnesses connected with both Listeria and Campylobacter since FoodNet surveillance began in 1996.
She said it was particularly exciting to see declines in STEC O157 and Shigella-related illnesses.
"After several years of really being at a plateau—to see those declines is heartening and just kind of makes us optimistic and gives us energy for trying to achieve further declines," Dr. Mahon said.
An editorial note in the MMWR states that improved prevention measures are needed to combat an increased incidence of Vibrio infection, which rose from 0.29 infections for every 100,000 people in the surveillance area in 2008 to 0.35 in 2009. The note also calls for improvements in understanding routes of exposure to the monitored pathogens, as recent outbreaks have been connected with novel sources including jalapeno peppers, peanut butter, cookie dough, and small birds and frogs.
Dr. Mahon said many pet owners may not be aware of the connection between pathogens and direct contact with animals.
Dr. John P. Sanders is section lead for food protection in the Department of Homeland Security's Office of Health Affairs and an alternate member of the AVMA Food Safety Advisory Committee representing the American Association of Food Hygiene Veterinarians. Dr. Sanders said that, while he was encouraged to see decreases in illness rates caused by most of the foodborne pathogens, he was concerned about the potential for diminished public health capacity at the state and local levels to detect and investigate food-related illness outbreaks.
The National Association of County and City Health Officials announced in March that an organizational survey indicated local public health departments lost 16,000 jobs in 2009. With about 7,000 jobs lost the year before, the organization estimated local public health department employment decreased about 15 percent in two years.
The Association of State and Territorial Health Officials reported that, of 45 public health departments surveyed, 76 percent had budget cuts during fiscal year 2009, and 61 percent had a smaller budget in fiscal year 2010 than in fiscal year 2009. About 27 percent cut staff through layoffs, 74 percent lost staff through attrition, 39 percent eliminated programs, and 74 percent reduced services.
USDA working to prevent illnesses
The CDC report cites data from the Department of Agriculture's Food Safety and Inspection Service that indicate about 7.2 percent of raw broiler chicken samples contained Salmonella in 2009, down from 11.4 percent in 2006. The recent decrease in STEC O157 infections may also be connected with effective controls in ground beef processing and produce growing.
The USDA announced May 10 the department would implement new performance standards for production of young broiler chickens and turkeys, and the standards are expected to prevent about 65,000 illnesses connected with Salmonella and Campylobacter yearly. The FSIS also released a compliance guide for industry intended to reduce Salmonella and Campylobacter in poultry and E coli O157:H7 in cattle.
The USDA announcement stated that the department had, in the past year, tested additional components of ground beef, instructed inspectors to verify that meat-producing plant employees follow sanitary practices in processing beef carcasses, appointed an FSIS chief medical officer, and issued new instructions on inspecting for E coli O157:H7 contamination.