U.S. health officials said on Wednesday that 338 people across 42 states fell sick due to salmonella poisoning and 70 have been sent to hospitals for treatment.

The U.S. Centers for Disease Control and Prevention is working with the Department of Agriculture, state health officials and the Food and Drug Administration in an attempt to try to tack the source of the outbreak which began in September.

This particular strain is known as Salmonella typhimurium and poultry, cheese and eggs are the most common source of this particular strain according to the CDC.

David Daigle, spokesman for the U.S. Center for Disease Control and Prevention, said, "It is often difficult to identify sources of food borne outbreaks. People may not remember the foods they recently ate and may not be aware of all of the ingredients in food. That's what makes these types of investigations very difficult."

Salmonella symptoms can range from diarrhea, fever and abdominal cramps which begin from 12 to 72 hours after infection sets in and usually last four to seven days. According to the CDC salmonella poisoning is not new to the United States and every year approximately 40,000 people are reported ill with many cases never being reported. April to August 2007 saw peppers from Mexico with salmonella that sickened 1400 people and an E. coli epidemic in 2006 which was the result of California spinach that resulted in three deaths.  The latest case being of salmonella contaminated dry pet food that sickened 79 people in October and November.

"Because foods of animal origin may be contaminated with Salmonella, people should not eat raw or undercooked eggs, poultry, or meat. Persons also should not consume raw or unpasteurized milk or other dairy products. Produce should be thoroughly washed," Daigle said.

The only state that has agreed to have their state named as one of those affected is Ohio, with an estimated 50 cases.