Pastoral livelihoods and the epidemiology of emergent trypanosomiasis on the Jos Plateau, Nigeria
Majekodunmi, Ayodele Oluwakemi
African trypanosomiasis is a widespread disease of livestock which is a major constraint to livestock production, mixed farming and the rural economy. The Jos Plateau in Nigeria was historically free of tsetse flies and trypanosomiasis and this lack of disease attracted large numbers of cattle keeping pastoralists. The area now plays an important role in the national/regional cattle industry, holding 300,000 pastoralists and over a million cattle, ~ 7% of the national herd. However, over the past twenty years tsetse flies have (re)invaded the Jos plateau and trypanosomiasis is now a significant problem. Little is known about the distribution and overall prevalence of the disease across the Jos plateau or about the habits and customs that could affect the epidemiology of the disease in this area. This knowledge is essential if successful interventions to reduce its impact are to be put in place. To bridge this gap, a longitudinal two stage cluster survey was carried out in 2008 to determine the prevalence of bovine trypanosomiasis. The study showed that the prevalence of trypanosomiasis across the Jos plateau was 46.8% (39.0 – 54.5%) with no significant seasonal variation. T. b. brucei was present at a prevalence of 3.3% (1% – 5.5%); T. congolense savannah at a prevalence of 27.7% (21.8% - 33.6%); T. vivax at a prevalence of 26.7% (18.2% - 35.3%). Although there was no significant seasonal variation in prevalence across the Jos plateau, seasonal variations were observed at village level to create 3 distinct groups. Group 1 villages (50.0%) which followed the expected pattern of low prevalence in the dry season and high prevalence in the wet season; Group 2 villages (16.7%) where there was no seasonal variation; Group 3 villages (33.3%) where paradoxically the prevalence was higher in the dry season and lower in the wet season. This reversed epidemiological pattern is attributed to the harsh climatic conditions of the dry season which reduce resistance to infection in cattle and increase vector – host contact. Migration was shown to be a significant risk factor for trypanosomiasis infection and the dry season was shown to significantly increase the effect of all risk factors. Participatory rural assessment was also conducted to investigate socio – economic factors and knowledge, attitudes and practices concerning tsetse and trypanosomiasis. The results of the participatory rural assessment exercise show that trypanosomiasis is well recognised by farmers on the Jos plateau. They are aware of the animal health and production disadvantages associated with it and make considerable efforts to control it, along with other livestock diseases. However, they lack the adequate knowledge to effectively control these diseases themselves and there are gaps in veterinary service provision. Wealth ranking showed that the majority of pastoralists in the study were either in the ‘middle’ or ‘better – off’ groups. Only 6.1% were classed as poor. Anaemia as an indicator for trypanosomiasis was investigated and FAMACHA charts were evaluated as a potential penside test for anaemia. Results show that anaemia in cattle on the Jos Plateau is not strongly related to trypanosomiasis and that the FAMACHA chart is a poor test for anaemia in cattle.