Prevalence and Genetic Characterization of Cryptosporidium Species in Dairy Calves in Central Ethiopia

The burden of cryptosporidiosis due to Cryptosporidium parvum is well documented in HIV-positive patients in Ethiopia. However, the role of animals in zoonotic transmission of the disease is poorly understood. The aim of this study was to determine the prevalence and genotypes of Cryptosporidium species in dairy calves; to assess the role of cattle in zoonotic transmission in central Ethiopia. A total of 449 fecal samples were collected and screened using modified Ziehl-Neelson staining method and PCR targeting the small-subunit (SSU) rRNA gene. The prevalence of Cryptosporidium was 9.4% (42/449) and 15.8% (71/449) as detected by microscopy and nested PCR, respectively. The prevalence of infection varied significantly across the study areas with the higher prevalence being observed in Chancho 25.4% (30/118). Crossbred calves had significantly higher prevalence of Cryptosporidium than indigenous zebu. Genotyping results revealed the presence of C. andersoni (76.1%), C. bovis (19.7%) and C. ryanae (4.2%). The occurrence of these Cryptosporidium species appeared to be age-related. C. andersoni constituted 92.1% of the Cryptosporidium infection in calves older than 3 months. Sequence analysis also showed the existence of intra-species variation at SSU rRNA gene. Findings of the current study indicate that cattle may not be an important source of zoonotic cryptosporidiosis in central Ethiopia. Further molecular studies are needed to support this observation from other part of the country.