Despite the odds of working in Chad, the project on rabies control of the Human and Animal Health unit 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 is does not need a fluorescence microscope and thus has a tremendous potential to be extensively used in peripheral field laboratories throughout Africa and Asia. Human rabies in developing countries can be prevented through interventions directed at dogs. To address potential cost-savings for the public health sector, cost-benefit and cost-effectiveness of interventions aimed at animal host reservoirs should be assessed.

Existing deterministic models of rabies transmission between dogs were extended to
include dog to human rabies transmission and fitted to routine weekly rabid dog and
exposed human cases reported in N’Djaména (Chad). Etimated transmission rates
were used to compute the basic reproductive ratio, R0, which was very close to 1, indicating low level endemic stability of rabies transmission. We simulated the effects of two interventions, mass dog vaccination and the culling of a percentage of the dog population. A single parenteral dog rabies mass vaccination campaign reaching an immune protection of at least 70% of the susceptible dogs appears to be sufficient to interrupt transmission of dog rabies for at least six years. Human post-exposure prophylaxis (PET) alone has no effect to reduce future human exposure. Combining human PET with a parenteral dog vaccination campaign becomes more cost effective than PET alone beyond a time horizon of 6-7 years. Owner valuation of dog vaccination cost indicates that dog mass vaccination must be free to the owners to reach a sufficiently high coverage to interrupt transmission.

Literature:
Dürr S, Naïssengar S, Mindekem R, Diguimbye C, Niezgoda M, Kuzmin I, Rupprecht CE, Zinsstag J. Rabies diagnosis for developing countries PLoS Negl Trop Dis. 2008 Mar 26;2(3):e206.    

Salome Dürr, Martin I. Meltzer, Rolande Mindekem, and Jakob Zinsstag (2008) Owner Valuation of Rabies Vaccination of Dogs, Chad. EID Volume 14, Number 10–October 2008

 

PD Jakob Zinsstag

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