Foodborne illnesses continue downward trend

Foodborne infections caused by several bacterial pathogens are on the decline, according to a report in the April 15 issue of the Morbidity and Mortality Weekly Report, which is published by the national Centers for Disease Control and Prevention. The Food and Drug Administration and Department of Agriculture collaborated with the CDC on the report.

The Foodborne Diseases Active Surveillance Network of CDC's Emerging Infections Program collects data from 10 sites in the United States on diseases caused by enteric pathogens transmitted commonly through food. FoodNet quantifies and monitors the incidence of these infections by conducting active, population-based surveillance for laboratory-diagnosed illness. The MMWR report describes preliminary surveillance data for 2004 and compares them with baseline data gathered from 1996-1998.

The report states that the estimated incidence of infection with Campylobacter decreased 31 percent, Cryptosporidium and Listeria decreased 40 percent, Shiga-toxin-producing Escherichia coli O157 decreased 42 percent, Yersinia decreased 45 percent, and overall Salmonella infections decreased 8 percent. The estimated incidence of Shigella infections did not change significantly in 2004 compared with the baseline period, and overall Vibrio infections increased 47 percent.

Although Salmonella incidence decreased overall, of the five most common Salmonella serotypes, only the incidence of S typhimurium decreased significantly, by 41 percent. This serotype, however, is still the most commonly reported Salmonella serotype. The report states that the estimated incidence of S enteritidis and S heidelberg did not change significantly, and incidence of S newport and S javiana increased 41 percent and 167 percent, respectively. The increase in S javiana cases was associated with a multistate outbreak linked to Roma tomatoes in 2004.

"Dramatic multiyear reductions in illnesses from E coli O157 mean the U.S. is now below (the) Healthy People 2010 goal of 1.0 case per 100,000 persons. This is a remarkable national achievement," said Merle Pierson, PhD, USDA acting undersecretary for food safety. "We are also very close to meeting the Healthy People 2010 goal set for illness from Listeria monocytogenes and Campylobacter."

The reductions in illnesses have occurred concurrently with several important food safety initiatives and educational efforts. The substantial decline of STEC O157 infections, first noted in 2003 and sustained in 2004, is consistent with declines in STEC O157 contamination of ground beef reported by the USDA Food Safety and Inspection Service for 2003 and 2004. Multiple interventions that might have contributed to this decline include industry response to the FSIS 2002 notice to manufacturers to reassess control strategies for STEC O157 in the production of ground beef. Enhanced strategies for reducing pathogens in live cattle and during slaughter may have also played a role.

The overall decline in Campylobacter incidence from the baseline period to 2004, the majority of which occurred before 2001, might reflect efforts to reduce contamination of poultry and educate consumers about safe food-handling practices. Although the incidence of Listeria infections decreased from the period 1996-1998 through 2004, the incidence in 2004 was comparable with 2002, after an increase in 2003.

The MMWR also states that the most common etiologies of outbreaks were norovirus (57 percent) and Salmonella (18 percent).