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Putting the Peanut Butter Salmonella Outbreak Into Perspective

By Daniel J. DeNoon
WebMD Health News

Reviewed By Louise Chang, MD

Jan. 21, 2009 -- Salmonella contamination of peanut butter products has sickened hundreds in the U.S. and Canada.

It's a scary situation. Here are some salmonella facts to put the current outbreak into perspective:

Every year, the CDC gets about 40,000 reports of salmonella illness. But that's only the tip of the iceberg, as only the most serious cases get reported. If milder cases are included, there are about 1.2 million U.S. cases each year.

The roasting process is supposed to be a "kill step" to keep salmonella from growing in peanut products. But if salmonella does get into peanut butter or peanut paste, further cooking may not kill the bacteria. That's because salmonella in relatively dry products enters a kind of vegetative state that allows it to survive heating.

Only one species of salmonella infects humans. But this species includes more than 2,300 different strains, technically known as serotypes or serovars. One serotype, Salmonella serotype Typhi, causes typhoid fever.

Most salmonella serotypes cause diarrheal illness in humans. The strain responsible for the peanut butter outbreak, Salmonella serotype Typhimurium, has about average virulence.

After ingesting salmonella bacteria, illness typically occurs within eight to 48 hours and lasts four to seven days. It begins with nausea and vomiting and progresses to intestinal cramping and diarrhea. Half of patients have a fever over 103 degrees Fahrenheit.

Non-typhoid salmonella treatment often requires no more than oral fluids for rehydration. People with severe dehydration may have to be given intravenous fluids in the hospital. When infection spreads from the intestines, antibiotics are needed. However, because of antibiotic use to promote growth of livestock, some salmonella strains are resistant to antibiotics.

Salmonella colonizes the intestinal tracts of humans and other animals. People catch salmonella by eating foods contaminated with feces. That's why restaurants carry signs warning workers to wash their hands before returning to work.

People with salmonella infection don't always have symptoms. A small percentage of people infected with salmonella become symptomatic carriers and may become chronic carriers for weeks and even for years.

Salmonella often colonizes the intestines of commercial poultry. It can be spread by contact with baby chicks. Children who handle chicks should immediately wash their hands thoroughly.

Salmonella often colonizes reptiles. Always wash your hands after handling a pet reptile.

Here's the CDC's advice on how to avoid salmonella infection:

Cook poultry, ground beef, and eggs thoroughly. Do not eat or drink foods containing raw eggs or raw (unpasteurized) milk.
If you are served undercooked meat, poultry, or eggs in a restaurant, don't hesitate to send it back to the kitchen for further cooking.
Wash hands, kitchen work surfaces, and utensils with soap and water immediately after they have been in contact with raw meat or poultry.
Be particularly careful with foods prepared for infants, the elderly, and the immunocompromised.
Wash hands with soap after handling reptiles, birds, or baby chicks, and after contact with pet feces.
Avoid direct or even indirect contact between reptiles (turtles, iguanas, other lizards, snakes) and infants or immunocompromised people.
Don't work with raw poultry or meat, and an infant (e.g., feed, change diaper) at the same time.
Mother's milk is the safest food for young infants. Breastfeeding prevents salmonellosis and many other health problems.

SOURCES: CDC web site. FDA web site. Virginia Bioinformatics Institute web site, Virginia Tech. University of Texas Medical Branch web site. News conference, Jan. 21, 2009, with Stephen Sundlof, DVM, director, Center for Food Safety and Applied Nutrition, FDA; and Robert Tauxe, MD, MPH, deputy director, Division of Foodborne, Bacterial and Mycotic Diseases in the National Center for Zoonotic Vectorborne and Enteric Diseases, CDC. Owens, M.D. eMedicine from WebMD, July 17, 2008.

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