A. Cryptosporidium is a microscopic parasite that is found in the feces of infected humans or animals. Humans are infected when they ingest contaminated water or food, or touch contaminated objects, then touch their mouth before washing their hands well. A. Symptoms of Cryptosporidium infection in people with normal immune systems include diarrhea that typically lasts one to two weeks, often accompanied by abdominal cramps, fatigue, nausea, vomiting, and low-grade fever. People usually develop symptoms two to 10 days after ingesting the parasite.
Serious illness needing hospitalization is uncommon.
A. People at risk for severe Cryptosporidiosis include people with AIDS, people who have cancer, or organ or bone marrow transplant patients who are taking drugs that suppress the immune system, and people who are born with genetically weakened immune systems. A. Cryptosporidium is a problem because most water from lakes, rivers, and streams contain some of the microscopic parasite. Cryptosporidium is highly resistant to chlorine and other disinfectants, which are used to kill bacteria and viruses in drinking water. In addition, Cryptosporidium is so small that the type of filters used in conventional municipal water treatment does not easily remove it from the water. Over half of the tested public water supplies that use surface water have been found to have small amounts of Cryptosporidium in the water sent to homes and businesses.