WEST POINT, Neb. (AP) — Health officials say the number of people stricken in a northeastern Nebraska salmonella outbreak has risen to 22.

The Elkhorn Logan Valley Public Health Department tell Sioux City, Iowa, television station KTIV that there have been 22 confirmed cases and six probable cases. The confirmed cases are up from 20 on Thursday.

The source of the outbreak hasn't been confirmed, but the department says investigators have found that all of the people stricken ate at Red Door Coffee in West Point. The department says the Red Door's owners and staffers are cooperating with investigators.

Medical experts say salmonella is caused by bacteria that live in the intestinal tracts of humans and animals. It usually is spread by eating contaminated food. Symptoms include fever, diarrhea and stomach cramps.