OMAHA — Nine people in southeast Nebraska have tested positive for E. coli infection in unrelated incidents.

Vicki Duey of the Four Corners Health Department says five people have tested positive for E. coli infection since her office was alerted last week.

She’s looking at whether food served at a public event may have sickened people. She won’t say where the event took place.

Her department covers Butler, Polk, Seward and York counties.

Meanwhile, state epidemiologist Tom Safranek says there are four confirmed cases of E. coli infection in the Auburn area of Nemaha County. He says three of the four sick people live in the same house, and the fourth came in contact with them.

The cause of those illnesses is under investigation.