 The Minnesota Department of Health is investigating reports of illnesses caused by a parasite. The probe started after a small number of guests at Great Wolf Lodge Water Park in Bloomington became sick in mid-June. Anyone who swam at the park in recent weeks has been asked to complete a survey whether they were ill or not. The MDH says those who have been sick had symptoms of diarrhea, stomach cramps, vomiting, and a low-grade fever.