Cryptosporidium parvum is a protozoan parasite infecting the gastrointestinal tracts of many vertebrates, including humans. An infected animal or
human suffers from cryptosporidiosis, a severe diarrheal disease, which lasts 1 to 2 weeks for immunocompetent individuals, but could be fatal for children and
immunocompromised individuals as there is no effective therapy. In Haiti, the intestinal cryptosporidiosis is caused by at least three species: Cryptosporidium
hominis, C. parvum and C. felis which are responsible for 17 % of acute diarrhea in children less than 2 years and 30 % of chronic diarrhea in HIV patients. Cryptosporidiosis
transmission in humans may occur through a number of routes, among which the ingestion of fecal contaminated drinking water is a major source.
Contamination of drinking water with Cryptosporidium oocysts is of particular concern since as few as one infective oocysts may cause infection. In previous studies,
Cryptosporidium oocysts have been detected in surface water and groundwater from three major cities of Haiti : Port-au-Prince, Cap-Haitian and Les Cayes.
Significant concentrations from 4 to 1274 oocysts in 100 liters of filtered water were found in Port-au-Prince ; in the city of Cap-Haitian 741 to 6088 and concentrations
ranging from 5 to 100 oocysts have been obtained in groundwater from Les Cayes. Results indicate that water resources in Haiti are widely contaminated
with Cryptosporidium oocysts. Therefore, they may constitute potential sources of biological risk particularly for human health. Since Cryptosporidium oocysts
are biological colloids, it is important to analyze the different risk factors associated with transfers of Cryptosporidium oocysts in aquatic ecosystems of Haiti.