Cryptosporidiosis of Livestock

Authors: Santin-Duran, Monica; Trout, James

Submitted to: CRC Press
Publication Type: Book / Chapter
Publication Acceptance Date: 6/6/2007
Publication Date: 1/1/2008
Citation: Santin, M., Trout, J.M. 2008. Cryptosporidiosis of Livestock. In: Fayer, R., Xiao, L., editors. Cryptospiridium and Cryptosporidiosis. 2nd edition. Boca Raton, FL. CRC Press. p. 451-483.

Interpretive Summary: For thousands of years, humans have relied upon domesticated livestock for food and fiber production. Currently, in industrialized nations, livestock are often raised under intensive, high density conditions. Although less developed nations tend to use more traditional husbandry methods, many are adopting more modern production systems, as well. Interestingly, Cryptosporidium infections have been reported in animals worldwide, regardless of the husbandry system used. Additionally, Cryptosporidium of animals can be infectious for humans. This chapter discusses the current state of knowledge of Cryptosporidium in cattle, sheep, swine, and other livestock. A greater understanding of Cryptosporidium infections is critical from two perspectives, animal health and human health. Cryptosporidiosis, especially in young animals, can cause severe illness or death, resulting in decreased performance and production losses. Calves, lambs, piglets, and goat kids can become severely ill following infection; resulting in financial loss to the producers from both extra care and supportive therapy needed and the death of production animals. Increased knowledge of Cryptosporidium species in animals and transmission potential can lead to better control strategies, resulting in healthier animals and greater production efficiency, which are essential to meeting the ever growing demand for food and fiber products. From the perspective of human health, many livestock harbor Cryptosporidium species that are infectious for humans. The close association of humans and livestock as well as the ability of runoff from animal production operations to contaminate water supplies represents an ever present risk of human infection. Cryptosporidiosis can be debilitating to healthy individuals and result in significant morbidity and mortality to special populations, such as children, the elderly, and the immunocompromised, even with modern medical treatment. Only molecular diagnostic techniques can differentiate species and genotypes of Cryptosporidium that are infections for humans from those that are not. Therefore in order to accurately assess the risk that livestock might pose to humans, molecular-based prevalence studies are necessary. Such studies could help to identify potential source of these organisms causing human infection, and lead to improved control strategies. Greater understanding of the species and genotypes present in animals and the patterns of transmission can improve our ability to control these infections will hopefully result in significant benefits to society in terms of both animal and human health.

Technical Abstract: This chapter discusses the current state of knowledge of Cryptosporidium in cattle, sheep, swine, and other livestock. A greater understanding of Cryptosporidium infections is critical from two perspectives, animal health and human health. Cryptosporidiosis, especially in young animals, can cause severe illness or death, resulting in decreased performance and production losses. Calves, lambs, piglets, and goat kids can become severely ill following infection; resulting in financial loss to the producers from both extra care and supportive therapy needed and the death of production animals. The differentiation of Cryptosporidium species and genotypes, which is necessary to understand parasite population dynamics and to evaluate the risk posed to humans, is possible only with molecular analysis of Cryptosporidium isolates. Although a number of genes can be used to perform this differentiation, the SSU-rRNA gene (aka the 18S gene) is arguably the most commonly used target for species and/or genotype identification. Currently, molecular analysis of Cryptosporidium spp. isolated from cattle has resulted in the identification of. 7 species and 3 genotypes in this host: C. parvum, C. andersoni, C. bovis, C. canis, C. felis, C. hominis, C. suis, C. suis-like genotype, Cryptosporidium spp. deer-like genotype, and Cryptosporidium spp. pig genotype II. In the few large scale prevalence studies in cattle to date, C. parvum, C. andersoni, C. bovis, and Cryptosporidium deer-like genotype are reported most frequently. Cryptosporidium bovis was named as a new species recently (Fayer et al., 2005), and was previously known as Bovine B genotype (Xiao et al., 2004). Cryptosporidium hominis has been reported in a few cattle in Scotland and Korea; C. suis was reported in 1 calf in the U.S. and 1 calf in; C. suis-like genotype was reported in 3 cattle in Denmark; Cryptosporidium pig genotype II was reported in 1 cow in Denmark and C. felis was detected in a single cow in Poland. Although C. canis, infection in calves has been demonstrated experimentally, to date, there are no reports of natural infections. C. parvum, C. andersoni, C. canis, C. felis, C. hominis, and C. suis, have been reported in human infections. In sheep in the United Kingdom a novel sheep genotype was the most predominant Cryptosporidium identified. In Australia, two novel genotypes were reported; novel Bovine B and a previously unknown genotype. In the United States a C. bovis-like genotype was reported. The two most recent molecular studies of Cryptosporidium isolates from sheep suggest that the cervine genotype, not C. parvum, is likely the most common species present in sheep. The cervine genotype has both a wide host and geographic range, having been found in sheep in Australia, lemur and white-tailed deer in North America, blesbok, mouflon, and nyala in the Czech Republic, and in humans in Canada, New Zealand, United Kingdom, Slovenia, and in the United States, and could emerge as an important zoonotic pathogen. This means that Cryptosporidium spp. oocysts excreted with feces of infected sheep can be a source of human infection. Natural infection of pigs with C. parvum, C. suis, and Cryptosporidium pig genotype II have been reported, and as discussed above, experimental infections with C. hominis and C. meleagridis have been successful. . Data thus far suggest that there could be age related differences in the prevalence of C. suis and the pig genotype II and that C. parvum might not be widespread in pigs. Cryptosporidium parvum is a well established pathogen in humans, whereas, to date, only sporadic cases of C. suis in humans have been reported. Treatment of cryptosporidiosis in animals remains problematic. Although a wide variety of compounds have been tested few have been found to be effective. Several studies in pigs suggest that hyperimmune bovine colostr