The impact and social ecology of bacterial zoonoses in northern Tanzania

Cleaveland, Haydon, Sharp, Halliday

It is well recognized that zoonotic pathogens - agents which can lead to diseases that are transmitted from animal to human populations - predominate as the cause of emerging human diseases, but in the shadow of the high-profile emerging zoonoses, such as Influenza A H5N1 and SARS corona virus, zoonoses that are prevalent in localised areas have often been overlooked.  However, awareness is growing that many of these localised zoonoses are responsible for a substantial burden of disease both in terms of public health and livestock health, and that these dual impacts contribute to perpetuating cycles of poverty in the marginalized communities that are most affected.  In northern Tanzania, the location of this research, human diseases caused by three zoonotic diseases (leptospirosis, Q-fever and brucellosis) result in 11 times as many hospital admissions as malaria.  However, almost nothing is known about transmission patterns among animal hosts, which host species are responsible for human disease, or the key behavioural determinants of human disease risk in different settings. 

The aim of this research is to quantify the impacts of these three zoonoses in different communities (located at the edge of town, in agricultural landscapes and in pastoral areas) and to develop a predictive understanding of the impact of environmental and social relationships on disease risk.  Specifically, they address infection and transmission patterns between animals and from animals to humans, ecological and social determinants of transmission, and the cultural, social, behavioural and economic and environmental dimensions of disease communication. The results of this work are directly applicable to policy and practice that is relevant to both public health and economic development related to livestock production.