CDC Investigating Salmonella Outbreak

By Annys Shin
Washington Post Staff Writer
Wednesday, November 1, 2006

Health officials suspect lettuce and tomatoes in a nationwide outbreak of salmonella that so far has sickened 171 people in 19 states, a spokeswoman for the Centers for Disease Control and Prevention said yesterday.

The spate of salmonella infections comes as federal and California state investigators are still searching for the cause of September's deadly spinach-borne E. coli outbreak, the 20th episode of foodborne illness linked to leafy greens in 10 years.

Investigators believe the salmonella outbreak has already peaked but they do not know the precise cause and have not linked it to any particular product, brand or distributor. But some food safety experts said that with so many cases and no source yet identified, the outbreak could widen. The typical produce-related outbreak involves an average of 43 people.

Salmonella infections cause 1.4 million cases of illness and 400 deaths in the United States every year, according to the CDC. Within 12 to 72 hours of infection, salmonella can cause diarrhea, fever and abdominal cramps that last four to seven days. It can be fatal for young children and the elderly. Most healthy adults recover.

Like E. coli , salmonella is a bacterium commonly found in warm-blooded animals that finds its way to the food supply through animal feces. It can be killed by thorough cooking. Washing can reduce the number of bacteria but may not get rid of all of them.

Salmonella infections are most often caused by eating undercooked meat, poultry or eggs, or other foods that have been become cross-contaminated through contact with raw meat or poultry. People have also become infected with salmonella after eating tomatoes, cantaloupe and alfalfa sprouts.

Eleven outbreaks of salmonella have been associated with tomatoes since 1990, according to the Center for Science in the Public Interest.

Illness linked to produce is a growing concern among food safety experts as Americans consume more fresh fruits and vegetables, on the recommendation of the federal government. Consumers are now more likely to get sick from a produce-related outbreak than from any other food source, said Caroline Smith DeWaal, director of food safety for the CSPI.

Every year, about 76 million people contract foodborne illnesses in the United States. About 325,000 of those cases require hospitalization, and 5,000 people die.

Several previous salmonella outbreaks have been associated with fresh fruit and produce. Last year, Orchid Island Juice Co. of Fort Pierce, Fla., recalled unpasteurized orange juice after 15 people fell ill. Salmonella-tainted Roma tomatoes sickened 561 people in 18 states and Canada during the summer of 2004.

Salmonella, which has also been found on almonds and pet reptiles, is more common than E. coli , said Larry Beuchat, a researcher at the Center for Food Safety at the University of Georgia. "Salmonella is present in a number of warm-blooded animals and reptiles in large numbers," he said. "There are larger number of reservoirs in nature than there are of E. coli ."

The strain involved in the current outbreak is a common variety called salmonella typhimurium , said Lola Russell, a CDC spokeswoman. The CDC receives about 6,000 to 8,000 reports of illness due to this strain every year.

Virginia health officials are looking into possible cases of salmonella infection related to the outbreak. Shannon Marshall, a health department spokeswoman, said it was premature to disclose how many cases the agency is investigating.

No deaths have been reported in connection with the outbreak, though 11 people have been hospitalized.

Health officials detected the outbreak by genetically matching strains of bacteria collected from victims and submitted by public health labs across the country to PulseNet, an electronic database maintained by the CDC.

The E. coli outbreak, which sickened more than 200 people and killed at least three, prompted federal officials in mid-September to warn consumers against eating fresh spinach. That warning was lifted after the outbreak was traced to four farms in California's Salinas Valley. Though investigators have not determined how the spinach came to be contaminated, they found the original strain in cattle feces collected within a mile of an implicated spinach field and in wild pigs known to pass through the field.

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