Seroprevalences of vector-transmitted infections of small-holder dairy cattle in coastal Kenya

A cross-sectional study was carried out from July to September 1989 in Kalo leni Division, Coast Province, Kenya to estimate the prevalence of vector-t ransmitted diseases in small-holder dairy cattle and to identify the risk f actors associated with different management systems. One hundred and thirty of the 157 herds with dairy cattle in Kaloleni Divis ion were surveyed. These were from three agro-ecological zones (coconut-cas sava, cashewnut-cassava and livestock-millet), comprised two management sys tems (stall-feeding and herded grazing) and were herds with either dairy ca ttle only or with Zebu and dairy cattle. A formal questionnaire sought answ ers to questions on cattle health and management practices. A total of 734 dairy and 205 Zebu cattle in 78 dairy and 52 mixed (dairy and Zebu) herds w ere sampled and screened for haemoparasites (Trypanosoma, Anaplasma, Babesi a, and Theileria infections). Sera were tested for antibodies to Theileria parva, using the schizonts-antigen indirect fluorescent-antibody (IFA) test and to antibodies for Babesia bigemina and antigens to Anaplasma marginale by enzyme-linked immunosorbent assay (ELISA). Packed-cell volume (PCV) als o was measured. Tick-control measures were practised by all except three of the farmers. De spite this, overall seroprevalence to T. parva was > 70% - suggesting eithe r that control practices were not strictly implemented or they were ineffec tive. The seroprevalence of T parva in adult cattle kept in stallfeeding sy stems in the coconut-cassava zone was significantly lower (57 +/- 8% (S.E.) ) than in herded-grazing systems (79 +/- 3%) and there was no association b etween antibody prevalence and age of cattle in this zone. Antibody prevale nces in cattle in the cashewnut-cassava and the drier livestock-millet zone increased with age. Cattle in herded-grazing systems had an overall lower seroprevalence of T parva infection in the livestock-millet zone (45 +/- 6% ) than in the other two zones.