Cryptosporidium

Abstract

Cryptosporidium sp. infects the gastrointestinal tract of a wide range of vertebrates, including domestic and livestock animals as well as humans. Cryptosporidiosis of neonatal farm ruminants causes considerable economic losses as the disease is commonly associated with intense diarrhea leading to an impaired growth, a decreased performance and production, and often animal death. The highly infective oocyst stage is excreted with the feces and disseminated into the environment, contaminating water and food. Neonatal calves are a major reservoir of the zoonotic C. parvum, which causes, in addition to the anthroponotic C. hominis, human cryptosporidiosis and is of considerable public health concern. Currently, no vaccine or efficient drug is available against the disease. From a veterinarian economical point of view, C. parvum is the most important species among the 30 recognized species infecting bovines, lamb, goats, pigs, horses, and dogs worldwide. After the discovery of C. parvum by Tyzzer in the year 1912, the taxon Cryptosporidium has been classified into coccidia. However, recent findings on the Cryptosporidium life cycle and molecular phylogenetic evidence resulted in the reclassification of Cryptosporidium into the gregarines. This novel placement appreciates previously underestimated and/ or neglected features of Cryptosporidium that are common to gregarines such as a low host specificity and/or the possibility to survive without a host.