Abstract
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Background: Cryptosporidium is an emerging opportunistic zoonotic pathogen that causes diarrheal illness in a wide range of hosts including livestock and humans. Globally there is an exponential increase in livestock production to meet the world demand for animal protein as well as for financial reasons. However, there is raised concern of the public health threat due to contamination of the environment by livestock waste carrying zoonotic pathogens such as Cryptosporidium. This study set out to establish the prevalence of Cryptosporidium as well as the circulating genotypes in order to elucidate the potential role of cattle in the spread of human cryptosporidiosis. We collected rectal coprological samples from 363 cattle in 11 households in Kiruhura district, Southwestern Uganda. The samples were screened for the presence of Cryptosporidium oocysts using the phenol auramine staining method followed by fluorescent microscopy. DNA was then extracted from the microscopy positive samples and the COWP gene amplified using PCR. Amplified gene products were sequenced and subjected to phylogenetic analysis. Results: The overall animal level prevalence of Cryptosporidium was 7.7% (95% CI: 5.1-10.9), and herd level prevalence was 33.3% (95% CI: 18.5-52.2). We found a statistically significant difference (p=0.02) between infection in bulls as compared to cows. There was however no significant difference in the prevalence among the different cattle breeds sampled, with the following prevalence observed in Crosses 9.2%, Ankole 5.7%, Friesian 7.1%, and Boran 2.8% respectively. The COWP gene was successfully amplified from 20 of the 28 microscopy positive samples. All the sequenced DNA amplicons were confirmed to be C. hominis, with 98%-100% identity to sequences in the GenBank. C. hominis was the only genotype isolated from this study, further asserting that cattle could be a potential high-risk source of human cryptosporidiosis. Conclusion: This study represents the first time naturally occurring C. hominis has been isolated from cattle in Uganda. This further provides evidence of cattle possibly being biological reservoirs for C. hominis and cattle could be a potential high-risk source of human cryptosporidiosis. Keywords: Cryptosporidium hominis; Cattle; Polymerase chain reaction; Genotyping; Uganda