The prevalence of serum antibodies to tick-borne infections in Mbale District, Uganda: by agro-ecological zone, grazing management and age of cattle

Abstract

Between August and October 2000, a cross-sectional study was conducted in smallholder dairy farms in Mbale district, Uganda to assess the prevalence of ticks and tick-borne diseases under different grazing systems and agro-ecological zones (AEZs) and understand the circumstances under which farmers operated. A questionnaire was administered to capture information on dairy farm circumstances and practices. A total of 102 farms were visited and sera and ticks were collected from 478 animals. Sero-prevalence of tick-borne diseases (TBDs) was determined using an ELISA. Acaricides were used indiscriminately but the intensity of their use varied with the grazing system and AEZ. Cattle from different farms mixed for various reasons. During the dry seasons farmers have to get additional fodder from outside their farms. The prevalence of ticks and serum antibodies to tick-borne infections differed across the grazing systems and AEZs. The highest serum antibody prevalence (>60%) was recorded in the lowland AEZ under the free range and tethering grazing systems. The lowest tick challenge and serum antibody levels (<50%) were recorded in the midland and upland AEZs under zero- 2 grazing system. These findings suggest that endemic stability to East Coast Fever, babesiosis and anaplasmosis is most likely to have existed in the lowland AEZ, particularly, under the tethering and free-range grazing systems. Also, endemic stability for babesiosis existed in the upland AEZs. Endemic instability for ECF existed in the midland and upland AEZs. These structured observational studies are instrumental in planning of control strategies for ticks and TBD’s since production systems and the cattle population at high risk of the diseases in the district have been identified.