[Detection methods and occurrence of Cryptosporidium sp. in selected surface waters].

Cryptosporidium, a small coccidian parasite, is accepted as an important cause of severe diarrheal illness in man and animals; in immunocompromised persons illness may be life-threatening. Cryptosporidium is transmitted by oocysts, passed in the faeces. These oocysts are remarkable resistant to common disinfectants and they can survive for several months. Person-to-person, animal-to-person and faecal contaminations of the environment are proven routes of transmission. Also waterborne disease outbreaks caused by Cryptosporidium are well documented. This paper represents a modification of a method for the detection of Cryptosporidium in water, developed by Musial et al. and Rose et al. The method includes steps for filtration, elution, centrifugation, flotation and microscopic detection of Cryptosporidium oocysts in sediments using an indirect immunofluorescence technique and a native contrast-technique. With this modified method efficiency of recovery ranged from 8.1% to 27.1%. In addition, selected surface waters in Northrhine-Westphalia were examined. The finding of Cryptosporidium oocysts in 7 of 9 water samples (78%) demonstrates the occurrence of Cryptosporidium oocysts in surface waters in Western-Germany. These results suggest that more detailed studies are needed to assess the risk of this new pathogen in water, especially in removal and disinfection in water treatment plants.