Epidemiology Of Cryptosporidium Spp. In Calves And Diarrhea In Livestock And Humans In Ethiopia
The Apicomplexa genus Cryptosporidium is comprised of over 20 species to date. While Cryptosporidium parvum is host adapted to cattle it is the most frequently reported zoonosis in people. Cryptosporidiosis associated with C. parvum infection is characterized by osmotic malabsorptive diarrhea, which can be fatal in immune-compromised individuals. Diarrhea is the second leading cause of disease burden worldwide across all ages, and is the second leading cause of death worldwide in children under 5. Therefore, the objectives of this research were to: 1) Describe the probability of Cryptosporidium parvum fecal oocyst shedding at different magnitudes of exposure to C. parvum, the pattern of fecal shedding over time, and factors affecting fecal shedding in dairy calves; 2) Characterize the dose-response relationship of Cryptosporidium parvum in experimentally challenged dairy calves, and determine the median infective dose based on this relationship; 3) Describe common animal husbandry and manure management activities and the associated division of animal husbandry labor by age and sex, and determine the risk factors associated with reported history of diarrhea among Ethiopian agro-pastoralists in the Amhara Region. It was determined that regardless of dose magnitude, all calves exhibited the same pattern of fecal shedding over time. There was a positive relationship between log-dose and diarrhea, and the ID50 for fecal oocyst shedding with diarrhea was 16.6 oocysts. This indicates that the best means of controlling cryptosporidiosis is at the calf level, through the provision of clean dry housing and adequate nutrition. When studying diarrhea among agro-pastoralists in Ethiopia, history of diarrhea in people was not associated with history of diarrhea in livestock or type of animal husbandry system, but was associated with household setting. There were also differences in division of animal husbandry labor, with women bearing the majority of the responsibility for manure management. This emphasizes the differences in potential disease exposure based on age and sex, the role of access to improved water sources in the prevention of diarrhea, and suggests that living in close proximity with livestock had no effect or may have a protective effect in some individuals with respect to diarrhea.
Cryptosporidium; calf; diarrhea; Ethiopia; dose-response; agro-pastoralist
Nydam, Daryl Van
Pell, Alice N; Mohammed, Hussni Omar; Bowman, Dwight Douglas
Ph.D. of Animal Science
Doctor of Philosophy
dissertation or thesis