Cryptosporidium spp. are protozoans known but the pathogenic role in human infection has been recognized only in the past few decades. Transmission is through the fecal‐oral route, thus poor hygienic practices promotes spread. Cryptosporidium is not susceptible to disinfectants, including chlorine. Hence transmission via contamination of drinking water can occur unless specific precautions are taken. Cryptosporidium spp. cause diarrhoea predominantly in children and in immunosupressed individuals. In fact, the greatest burden of disease is among children in developing countries where the parasite is implicated as a cause of persistent diarrhoea and malnutrition in children. The prevalence of this infection is likely underestimated due to limitations in diagnostic testing even in developed countries. Treatment with nitozoxanide achieves cure in children. However results are not less dramatic in individuals with depressed cellular immunity.

Keywords: Cryptosporidium; cryptosporidiosis; diarrhea; AIDS; HIV; nitazoxanide

Figure 1.

Life cycle of Cryptosporidium spp. Humans are infected by ingestion of the oocyst. After ingestion of oocysts (a), the sporozoites (b) attach to and are engulfed by the enterocytes. Inside the enterocyte, the organisms enlarge to form the trophozoites (c) and divide to form the Type I meronts (d and e). Merozoites are released, which reinvade epithelial cells to form Type II meronts (f), which differentiate into the gamontes (g and h), which fuse to form the zygote (i). Zygotes differentiate into thin‐walled oocysts (j), which lead to autoinfection or thick‐walled oocysts (k), which are shed into the environment and infect other hosts. Modified from



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Further Reading

Fayer R and Xiao L (eds) (2008) Cryptosporidium and Cryptosporidiosis, 2nd edn, pp. 1–525. Boca Raton, FL: CRC Press.

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Bhaskaran, Archana, and White, A Clinton(Mar 2009) Cryptosporidiosis. In: eLS. John Wiley & Sons Ltd, Chichester. [doi: 10.1002/9780470015902.a0001950.pub2]