Influence of cattle movement, ecological and risk factors on trypanosome infections of cattle in Simanjiro and Monduli districts, Tanzania

Abstract

African animal trypanosomiasis is a neglected tropical disease with significant impacts on pastoral community livelihoods. This study sought to determine the influence of seasonal cattle movements and risk factors including age, sex, and herd size and treatment intervention, in conjunction with studying ecological factors on trypanosome infections in cattle in of the Maasai steppe in northern Tanzania. To identify potential hotspots areas of trypanosome transmission and associated ecological factors, I worked with five pastoralist households in each of three study villages in the Maasai steppe. Consecutively, 10 individual cattle were sampled in three periods, covering both wet and dry months grazing ranges (July, 2017 to January, 2018). Each time a blood sample was collected from the cattle, a prophylactic dose of diminazene aceturate was administered to clear any trypanosome infections acquired in the previous three months. Participatory mapping techniques were then used to identify the areas in which each pastoralist had grazed their herds since the last sampling period. Herders were also interviewed about the presence of cultivated farms and other habitat types observed in grazing areas, the abundance of wild animals per visit, risk factors related to the cattle, previously infected cattle and any disease control methods they had practiced since my last visit. Trypanosome infections in the blood sample were detected using nested polymerase chain reaction with ITS-1 primers. The overall prevalence of trypanosome infections across all sampling periods and villages was 13.1%. Prevalence in July, 2017 (19.3%) was significantly greater than prevalence in October, 2017 (2%) (P<0.05). Cattle acquired trypanosome infection in 21 out of 45 grazing areas identified. Herd sizes between 51-100 cattle were observed to be positively associated with the prevalence of trypanosome infections in different villages. Wild animal abundance particularly buffaloes together with their habitat types, notably woodland, were observed to be positively associated with trypanosome infection while cultivation was negatively associated with trypanosome infections. Targeted awareness on influence of seasonality, hotspot areas, risk factors, ecological factors and cultivation of trypanosome infections will help Maasai pastoralists to plan movement of their cattle strategically, properly controlling and avoiding disease risks.