Health officials continue to search for the source of a St. Louis-area E. coli outbreak that has now sickened 22 people.

Nine people ranging in age from 4 to 94 have been hospitalized. KMOX Radio reports that the illnesses are not believed to be life-threatening.

St. Louis County Health Department spokesman John Shelton says this appears to be a particularly virulent strain.

E. coli are a group of bacteria that can cause diarrhea, urinary tract infections, respiratory illness and pneumonia. The illness is typically spread through consumption of contaminated food, unpasteurized milk, contaminated water or contact with the feces of infected people.

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