Identifying Variation Among Human, Animal and Environmental Isolates of Cryptosporidium

Publisher Summary This chapter focuses on identifying variation among human, animal, and environmental isolates of Cryptosporidium . It describes the detection and the distribution of a variety of Cryptosporidium spp . and C. parvum genotypes, including novel isolates. Human disease is usually caused by Cryptosporidium parvum , in which two genotypes predominate. The host range of genotype 1 is usually limited to humans, but genotype 2 has a broad range of human and animal hosts. The detection of genotype 1 is indicative of a human source of infection or contamination and genotype 2 of either an animal or a human source. During the investigation of outbreaks of human illness associated with recreational and drinking waters, timely characterization of isolates from clinical cases proves to be useful. Environmental isolates to contribute to the epidemiological picture have been successfully genotyped. Careful interpretation is required since environmental conditions and extraction methods will impact on the isolates detected, while parasite specificity, infectivity, host selection, and immunity will influence significance for consumer health. Other genotypes and species of Cryptosporidium are also detected, but more rarely.