Rabies in Ethiopia: modelling the burden and the effectiveness of control

Rabies claims the lives of more than 24,000 people in Africa annually, but efforts to control the disease are still lacking, particularly in sub-Saharan Africa such as Ethiopia. The overall objective of this study was to support the design of an appropriate cost-effective rabies control policy in Ethiopia by providing insights in the health burden of the disease and its economic impacts, as well as an understanding of the relationship between intervention levels, implementation costs and potential returns. As most human rabies cases result from the bite of domestic dogs, the disease can be eliminated by mass canine rabies vaccination. An extensive literature review on mass canine vaccination programs in Africa indicated that most dogs in Africa are owned and therefore accessible for vaccination, but vaccination coverages strongly depend on the implemented cost schemes. Canine vaccination in Ethiopia is voluntarily based, i.e. “owner-charged”, resulting in one of the lowest coverages in the world. To assess the current burden of rabies in Ethiopia a retrospective study was conducted by collecting data on human rabies exposure over the period of one year through extensive bite case searching in three representative districts of Ethiopia. Extrapolation of the results to national level indicated an annual average of 3,000 human deaths and 97,000 rabies-exposed persons treated at an average costs of 21 USD per case, causing 2 million USD on treatment costs per year and a health loss of about 93,000 DALYs. About 77% of the exposure cases visited a health centre, while only 57% received sufficient doses of post exposure treatment. Important factors that influenced victim’s medical treatment seeking behaviour were ownership status of the biting dog, severity of the bite, body part bitten, monthly spending and distance to the nearest health centre whereas the likelihood of receiving sufficient doses of treatment were determined by monthly spending and distance to health centre. The district in which victims lived appeared to have a relevant influence on the likelihood of seeking medical treatment but not on the likelihood of treatment compliance. By means of a structured questionnaire administered to cattle-owning households the economic impact of rabies in livestock was assessed. Herd-level incidence rates appeared higher in the mixed crop-livestock system (21%) than in the pastoral system (11%). Average economic losses per herd due to rabies were estimated at 49 USD per year for the mixed-crop livestock system, and at 52 USD per year for the pastoral system. In light of policy support for rabies control, an evaluation of the cost-effectiveness of control strategies was performed by the use of a dynamic epidemiological model coupled with an economic analysis to predict the human health impact and economic benefit (reducing human treatment costs and livestock rabies-related losses) across a range of vaccination scenarios. Human exposures, human deaths, and rabies-related livestock losses decreased monotonically with increasing vaccination coverage. In the evaluated urban and rural districts, 50% coverage was identified as most likely scenario to provide the greatest net health benefits at the WHO-recommended willingness-to-pay threshold over a time frame of 10 years. The additional economic benefit from rabies control in livestock justified the additional costs of vaccination campaigns with higher coverages than would have been efficient from a strict human health perspective, highlighting the importance of applying a broad perspective with regard to the evaluation of vaccination benefits.