A federal investigation into a multistate outbreak of a foodborne bacterium that hospitalized three people is over, according to the Centers for Disease Control and Prevention (CDC).

In total, the CDC identified nine people across three states who were sickened with Escherichia coli after eating cheddar cheese or drinking milk from Raw Farm, LLC, a dairy in California's Central Valley that sells unpasteurized products.

The CDC said that half the people harmed in the outbreak were kids under 5. One person developed hemolytic uremic syndrome, a serious condition that can cause kidney failure. No deaths have been reported.

The Food and Drug Administration recommended that Raw Farm voluntarily remove its products after a sample of its raw cheddar tested positive for E coli O157:H7, a particular strain of the bacterium. 

The dairy initially declined that mid-March request, only to issue a voluntary recall two weeks later, saying it was done under protest. On April 2, Raw Farm withdrew its first statement and instead said it "reserves its rights and disputes being the cause of this outbreak."

Pasteurized is best

People sickened by E coli often experience severe stomach cramps, diarrhea, or vomiting roughly three to four days after swallowing the bacterium. Most recover without treatment. 

To avoid foodborne illness, the CDC advises that people wash their hands, utensils, and surfaces often and rinse produce under running water before eating, cutting, or peeling. Consumers are also advised to refrigerate perishable foods and separate cooked foods from raw foods.

The agency recommends that people choose pasteurized dairy products. Pasteurization removes disease-causing germs by heating milk to a high enough temperature for a certain length of time.

"This is especially important for children under 5 because they are more likely to get a severe foodborne illness," says the CDC.