Food contaminated with Salmonella can cause salmonellosis, one of the most common bacterial foodborne illnesses, estimated to afflict from 2 to 4 million Americans annually.

The disease is widespread in animals, especially in poultry and swine. Environmental sources of the organism include water, soil, insects, factory surfaces, kitchen surfaces, animal feces, raw meats, raw poultry, and raw seafoods, to name only a few.

Foods generally associated with Salmonella include raw meats, poultry, eggs, milk and dairy products, fish, shrimp, frog legs, yeast, coconut, sauces and salad dressing, cake mixes, cream-filled desserts and toppings, dried gelatin, peanut butter, cocoa, and chocolate.

Various Salmonella species have long been isolated from the outside of egg shells. The present situation is complicated by the presence of the organism inside the egg, in the yolk.

As few as 15 cells can cause the disease, depending on the age and health of the infected person and the strength of the various strains. Onset time is usually 6 to 48 hours.

Acute symptoms include nausea, vomiting, abdominal cramps, minal diarrhea, fever, and headache. Arthritic symptoms may follow 3-4 weeks after the onset of acute symptoms.

Acute symptoms may last for 1 to 2 days or may be prolonged, again depending on host factors, ingested dose, and strain characteristics.

Diagnosis is through serological identification of culture isolated from stool.

The incidence of salmonellosis appears to be rising both in the U.S. and in other industrialized nations. The strain known as S. enteritidis has shown a dramatic rise in the past decade, particularly in the northeast United States, and the increase in human infections is spreading south and west, with sporadic outbreaks in other regions.

Safety Tips

The USDA recommends cooking poultry products to an internal temperature of at least 165 degrees Farenheit. Egg yolks should be cooked thoroughly so that they are not "runny."

Food preparation surfaces must be kept clean and cooking instruments, including sponges and dish towels, must be washed thoroughly after each use.

Consumers with food safety questions can phone the toll-free USDA Meat and Poultry Hotline at 1-888-MPHOTLINE. The hotline is available in English and Spanish and can be reached from 10 a.m. to 4 p.m. (Eastern Time), Monday through Friday. Recorded food safety messages are available 24 hours a day.

Ready to Cook, Not Ready to Eat

Products labeled with phrases such as "Cook and Serve," "Ready to Cook," and "Oven Ready" are intended to convey to the consumer that the product is not ready-to-eat and must be fully cooked for safety. Although products may appear to be pre-cooked or browned, such products should be handled and prepared no differently than raw product.

Many frozen entrees containing stuffed poultry products, such as a poultry product stuffed with cheese and other ingredients, typically are not-ready-to-eat and must be fully cooked as if they were raw.

Consumers must always follow the microwave instructions completely.

If using a microwave oven to cook meat and poultry products, be sure to take multiple temperature readings at different locations throughout the product due to the non-uniformity of the heating process and the creation of "cold spots."

Because a microwave oven typically cooks product at non-uniform rates, it is important to ensure that the product is covered sufficiently for steam to build in the product, and that the product is set aside for a sufficient time for the heat to uniformly spread throughout the product at the completion of the microwave cycle. This will ensure that there are no "cold spots."

Sources: USDA, FDA