PREVALENCE AND MOLECULAR CHARACTERIZATION OF CRYPTOSPORIDIUM SPECIES. FROM HUMANS AND CATTLE IN ADDIS ABABA AND ITS ENVIRONS, ETHIOPIA
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Date
2017-06
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Abstract
Cryptosporidiosis causes significant diarrheal disease in humans and animals worldwide. In
this study, conducted during June/2014 to June/2015, cross-sectional and longitudinal study
designs were employed to determine the magnitude of Cryptosporidium infection in humans
and cattle and to assess its public health significance in Addis Ababa and its surrounding area.
The objectives of the study were to determine the prevalence, characterize species of the
parasite and identify risk factors of the infection in humans and dairy cattle in the area. Faecal
samples collected from 422 cattle and 300 humans were examined by the Modified Ziehl-
Neelsen, PCR-RFLP and sequencing. Data on risk factors of the infection were collected using
a pre-tested questionnaire and analysis was made by the SPSS software. The overall
prevalence of Cryptosporidium in cattle and humans was 18.6% (95% CI: 14.8–22.5) and 9%
(95% CI: 5.5–12.3), respectively. Cryptosporidium andersoni (73.3%) and C. parvum (26.7%)
were identified in cattle, whereas C. parvum (81.5%) and C. hominis (18.5%) were detected in
humans. In cattle, Cryptosporidium infection was significantly associated with absence of
calving pen (OR=2.46, 95% CI: 1.08–5.61), absence of calf bedding (OR=10.55, 95% CI:
4.89–22.66), drinking river/stream water (OR=2.9, 95% CI: 1.5–5.5) and group penning of
calves (OR=2.7, 95% CI: 1.0–7.0). While in humans, the infection showed significant
association with drinking stream/well water (OR=3.3, 95% CI: 1.5–7.4) and contact with cattle
and their faeces (OR=3.6, 95% CI: 1.4–9.5). Cryptosporidium infection occurred from week 1
to 3 months of age in calves with an overall prevalence of 40% (12/30), and pre-weaned and
post-weaned calves were merely infected with C. parvum and C. andersoni, respectively.
Phylogenetic analysis showed that the C. parvum human isolates belong to the bovine
genotype family. In conclusion, the zoonotic C. parvum is prevalent and widely distributed in
cattle and humans in the study area, pre-weaned calves are the potential risk group for human
infection requiring special management attention to prevent transmission of the infection to
humans and lessen contamination of the environment.
Description
PhD Thesis
Keywords
Cattle, Cryptosporidium, PCR-RFLP