A study of factors influencing endemic stability and instabiity to theileriosis and babesiosis on dairy production in Muranga district, Kenya uri icon

abstract

  • This thesis describes a study of the epidemiology of theileriosis on smallholder dairy farms in Murang'a District situated in central highlands of Kenya. The main objectives were: 1) to characterise different areas within the district as to their risks for tick-borne diseases (TBDs), in particular infection due to Theileria parva, and to classify the potential endemically stable and unstable areas. 2) Estimate health and productivity parameters such as infection rates, morbidity and mortality rates, dynamics of infection and growth patterns in contrasting grazing systems and agro-ecological zones (AEZs) in Murang'a District, Kenya. 3) To study the potential risk factors associated with T parva infections in cattle in smallholder dairy farms in Murang'a District of Kenya. The study was conducted in two phases. The first phase was a cross-sectional study to estimate the prevalence to tick-borne infections and was conducted between March and June 1994. The cross-sectional serological study was carried out on 750 smallholder dairy farms in Murang'a District, selected in a stratified random sampling method. One hundred and fifty farms were studied from three administrative sub locations in each of the five AEZs. These five AEZS were: Lower Highlands 1 (LH 1), (tea-dairy; altitude, 1730-2130m; mean annual temperature, 15-18°C; annual rainfall, 1700-240Omm); Upper Midlands 1 (UM 1), (coffee-tea; altitude, 1670-180Om; mean annual temperature, 18.0-18.8°C; annual rainfall, 1700-190Omm); UM 2 (main coffee; altitude, 1500-167Om; mean annual temperature, 18.8-19.7°C; annual rainfall, 1300-162Omm); UM 3 (marginal coffee; altitude, 1340-150Om; mean annual temperature, 19.7-20.7°C; annual rainfall, 900- 135Omm); and UM 4 (sunflower-maize; altitude, 1340-152Om; mean annual temperature, 19.5-20.7°C; annual rainfall, 850-95Omm). The farms had a total of362 calves (148 males and 214 females) aged between 6-18 months. Prevalence of serum antibodies to three tick-borne parasites, that is T parva, T mutans and Babesia bigemina, were determined using the Enzyme-Linked Immunosorbent Assay (ELISA) technique. Antibody prevalence values significantly differed across the AEZs. The ranges of means for the antibody prevalence were: T parva (18-72%), T mutans (1.5-28%) and B. bigemina (12-49%). There were significant differences in serum antibody prevalence for the different TBD parasites across the fives AEZs (po.05). The factors significantly associated with sero-conversion to T parva in a multi-variate Glimmix model are briefly described below. Zebu breeds and their crosses with exotic breeds were associated with lower risks of seroconversion to T parva than the exotic breeds (p

publication date

  • 1997