The effect of El Nino on trypanosome infection in cattle in Dar es Salaam, Tanzania: A retrospective field report

A retrospective study was carried out to assess the effect of El Nino on trypanosome infection in cattle. Trypanosome infection was monitored in free grazing dairy cattle before and after El Nino in Dar es Salaam. The study involved 49 smallholder dairy herds with a total of 570 dairy cattle. Trypanosomes were identified by microscopic examination of Giemsa- stained blood smears. The rate of trypanosome infection after El Nino in each location with figures before El Nino in brackets were 24.8% (8.0%) in Makongo juu, 28.0% (8.7%) in Madale, 35.6% (14.9%) in Bunju, and 0.5% (4.9%) in Beach areas. The results also indicated that cattle exposure to tsetse challenge was higher in high altitude parts of Dar es Salaam  compared to low-lying areas after El Nino. The observation suggests that El Nino phenomenon influenced tsetse redistribution in many tsetse endemic areas and the increase in infection rate after El Nino was a result of  increase in tsetse fly population. It is recommended that the effect of  weather changes be taken into consideration when offering animal health and extension services on trypanosomosis control. Key words : Dar es Salaam, El Nino, dairy cattle, trypanosomes, tsetse fly