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Differences in the epidemiology of theileriosis on smallholder dairy farms in contrasting agro-ecological and grazing strata of highland Kenya

Published online by Cambridge University Press:  01 April 2000

G. K. GITAU
Affiliation:
International Livestock Research Institute, P.O. Box 30709, Nairobi, Kenya Department of Clinical Studies, University of Nairobi, P.O. Box 29053, Nairobi, Kenya
J. J. McDERMOTT
Affiliation:
International Livestock Research Institute, P.O. Box 30709, Nairobi, Kenya
J. M. KATENDE
Affiliation:
International Livestock Research Institute, P.O. Box 30709, Nairobi, Kenya
C. J. O'CALLAGHAN
Affiliation:
Ecosystems Analysis and Management Group, Department of Biological Sciences, University of Warwick, Coventry, CV4 7AL, UK
R. N. BROWN
Affiliation:
Department of Pathology, Microbiology and Immunology, University of California, Davis, California, 95616, USA
B. D. PERRY
Affiliation:
International Livestock Research Institute, P.O. Box 30709, Nairobi, Kenya
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Abstract

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A prospective cohort study was conducted in five purposively-sampled agro-ecological zone (AEZ)-grazing system strata in Murang’a District, Kenya, between March 1995 and June 1996. The study strata were selected based on a preliminary characterization study to represent the widest range of risks to East Coast fever (ECF) in the District and included zero-grazing and open-grazing farms. In total, 225 calves from 188 smallholder farms were examined from birth to 6 months of age and visited within the first 2 weeks of life and thereafter at bi-weekly intervals for up to 14 visits.

The purpose of the study was to characterize the differences in epidemiology (risks of infection, morbidity and mortality) and potential control of ECF between the selected strata. Evidence of Theileria parva infection was assessed by increased antibody levels as measured in an indirect ELISA assay by the percent positivity (PP) of serum samples relative to a strong positive reference serum.

Sero-conversion risks of T. parva were highest in the open-grazing strata. Antibody prevalence in adult cattle and ECF morbidity and mortality risks were also highest in open-grazing strata. While different, all five AEZ-grazing strata were considered to be endemically unstable for ECF. East Coast fever challenge was low in all zero-grazing strata and this challenge is likely to remain low due to continuing intensification of smallholder farming in the central highlands. In the open-grazing strata, there was higher challenge and a greater impact of ECF.

Type
Research Article
Copyright
© 2000 Cambridge University Press