Despite the odds of working in Chad, the project on rabies control worked very well and showed, after a first study by another group in Tanzania (Lembo et al. 2006), that the new direct immuno-histochemical test (dRIT, Biotinyl coupled anti-rabies antibody, streptavidin-peroxidase detection system) of CDC has the same performance as the Immunefluorescence gold standard. The main advantage is that it does not need a fluorescence microscope and thus has a tremendous potential to be extensively used in peripheral field laboratories throughout Africa and Asia.
Confronted with the lack of funds for dog rabies mass vaccination Rolande Mindekem and Salome Dürr could show that willingness to pay for dog rabies vaccination follows empirical observation. While vaccination coverage reaches >70% if dog vaccination is free, it drops to 20% if owners have to pay 4 US$. With routine data for weekly rabid dogs and exposed humans over 6 years, we could fit a dog-human rabies transmission model and show that in N’Djaména there is nearly endemic stable rabies transmission with an R0 = 1.05. One single dog mass vaccination reaching 70% coverage is sufficient to eliminate rabies for at least six years. Culling exercises are much less effective and socially not acceptable. Comparative cost of rabies control by rabies vaccination is cheaper than the “do nothing”alternative of human post-exposure treatment (PET) after 5 years. Comparative cost-effectiveness of dog mass vaccination is cheaper than PET after 4 years and reaches 33 $US/DALY averted after six years.
One of the involved students (Salome Dürr) received the first prize of the young scientist award at the Austrian-German-Swiss epidemiology conference in Oberschleissheim (Sept. 5.-7. 2007). The work on the transmission model is currently extended to an individual based stochastic version in collaboration with Timo Smieszek at ETHZ.
Jakob Zinsstag, DVM PhD
Swiss Tropical Institute
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Pictures (click to enlarge)
Left picture: pilot vaccination campaign of dogs
Right picture: pilot dog vaccination campaign community awareness
