FACTBOX: Key facts about salmonella

CHICAGO (Reuters) - The U.S. Food and Drug Administration (FDA) has reported 167 cases since mid-April of salmonella poisoning that it believes are related to certain types of tomatoes.

The FDA said it has not yet identified the source of the salmonella, which has caused 23 people to be hospitalized. A rare strain of salmonella, called Salmonella Saintpaul, is said to be causing the current outbreak.

Here are some key facts about salmonella:

* People infected with salmonella usually have symptoms that include diarrhea, fever, nausea and stomach cramps that generally start within about 12-72 hours after eating infected food. The sickness usually lasts four to seven days.

* Severe infections are possible if salmonella spreads from the intestines to the bloodstream. Infants, the elderly and people with weaker immune systems are more susceptible, and antibiotics may be needed. The infection can cause death unless a person is treated with antibiotics.

* Raw or undercooked meat, poultry and eggs should not be eaten. Fruits, such as tomatoes, should be washed thoroughly.

* Keep meat and other foods separate to avoid cross contamination.

Source: Centers for Disease Control and Prevention