PIERRE, S.D. (KWAT) — The South Dakota Department of Health has closed the books on its investigation into an E-Coli outbreak in Sisseton.

Dr. Joshua Clayton is the state epidemiologist.

The Health Department looked for a source of the E-Coli, but didn’t have any luck finding it.

Clayton says some of the victims were sick enough that they required hospitalization, but they’ve since recovered.