A fifth case of E. coli possibly linked to the Red River Valley Fair was confirmed Tuesday by the North Dakota Department of Health.

The case joins four others that have been confirmed in the last two weeks. All five cases are from eastern North Dakota and four out of the five have been hospitalized, said Michelle Feist, an epidemiologist with the Health Department.

Feist said the investigation into the root causes of the E. coli outbreak is ongoing. She asks anyone who experienced illness after attending the fair, especially gastrointestinal illness like diarrhea or vomiting, to fill out a survey on the Health Department website to determine if their cases are related.