Maryland - Parasite Found in Drinking Water Affecting the Immunocompromised within a Population of Nearly 1.8 Million Residents A microscopic parasite called Cryptosporidium was found during testing of Druid Lake Reservoir. This parasite can cause gastrointestinal problems in those who are immunocompromised, the elderly, and/or children. The parasite can cause cryptosporidiosis which, according to the CDC • Watery diarrhea • Stomach cramps or pain • Dehydration • Nausea • Vomiting • Fever • Weight loss Baltimore, Baltimore County and Howard County are the affected areas. Residents can use this Interactive Map to determine if they live in an impacted area....