Schlüsselwörter
(Englisch)
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Dog rabies, diagnostic test, deterministic transmission model, cost-effectiveness, Chad, Mali
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Kurzbeschreibung
(Englisch)
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Every year, 40,000 to 70,000 people die of rabies. Most of these deaths occur in tropical developing countries. The
domestic dog is the main vector for human rabies and exposure. Exposed persons can be saved through post-exposure treatment (PET), which is however, not always available in developing countries. Canine rabies could be controlled and human exposure and rabies cases could be prevented through vaccination of the animal vector. The World Health Organization (WHO) estimates the threshold vaccination coverage for eradication in a dog population empirically at about 70%. Constraints to dog mass vaccination are inaccessible ownerless dogs and insufficient community participation. There are, however examples of successful dog vaccination programs. With limited resources, the question of intervention cost becomes crucial in the discussion of what strategy of prevention to use. WHO estimated that over a period of 15 years, dog vaccination combined with post-exposure treatment for exposed patients is more cost-effective than PET alone, where the virus still circulates in the dog population. However, little is known about the real cost of intervention through mass vaccination of dogs.
In the framework of a research partnership, co-funded by BVET, between the Swiss Tropical Institute (STI), the
Laboratoire de Recherches Vétérinaries et Zootechniques de Farcha (LRVZ), and the Centre de Support en Santé Internationale au Tchad (CSSI/T), we conducted a study on canine rabies in N'Djaména, Chad. The study consisted of an incidence study, an estimation of the urban dog population and a parenteral pilot vaccination campaign. Dog rabies is endemic in N'Djaména with a yearly incidence risk of 1.4 per 1,000 unvaccinated dogs (Kayali et al. 2003a). A representative household survey on knowledge, attitudes and practices towards rabies in the urban population of N'Djaména revealed that 19% of all owned dogs were vaccinated (presence of a vaccination certificate). The most important constraints to vaccination were transport and the cost of the vaccine (Mindekem et al. 2004). Exposed persons do not find a full-course treatment, and often start PET with a delay due to shortages of vaccine or financial constraints. With the pilot mass vaccination high vaccination coverage of 64-87% was reached in the dog population due to good community and owner participation in the free campaign and the low number of ownerless dogs (Kayali et al. 2003b). In a national conference on rabies in Chad organized in the framework of this collaboration, delegates reported the presence of rabies mostly from the southern part of the country. However, except for N'Djaména there is no other diagnostic facility in the whole country for a population over 7 million people. Due to the poor transport infrastructure, samples can hardly be shipped over longer distances. The presented project proposes to validate a new light microscopic diagnostic test which could be established in field laboratories and hence increase decentralised diagnostic capability.
In Switzerland rabies was eliminated with a massive financial and logistical effort. But in a low income country like
Chad, neither the means nor the capacity is available for this. However, if rabies could be controlled in the main urban centres, the public health importance of rabies could be strongly reduced. Currently WHO reviews different strategies to identify the most cost-effective but also acceptable and feasible ways to control rabies in developing countries. Based on our work in Chad we were invited to participate in a WHO working group on the economics of rabies control. We developed a first dog-human rabies transmission model as a tool to assess comparative cost-effectiveness of different rabies control strategies. Preliminary analyses show that dog vaccination becomes comparatively more cost-effective on a time horizon of 8-10 years compared to human PET alone. The model
developed is analogous to a livestock-human brucellosis transmission model developed by J. Zinsstag and colleagues (Roth et al. 2003). The present project proposes to develop and validate a full dynamic transmission model linked to an economic assessment tool to assess comparative cost-effectiveness of rabies control in developing countries as evidence base for policy planning.
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Publikationen / Ergebnisse
(Englisch)
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Dürr S, Naïssengar S, Mindekem R, Diguimbye C, Niezgoda M, et al. (2008) Rabies Diagnosis for Developing Countries. PLoS Negl Trop Dis 2(3): e206. doi:10.1371/journal.pntd.0000206
Dürr, S.; Mindekem, R.; Kaninga, J.; Doumagoum Moto, D.; Meltzer. M.I.; Vounatsou, P.; Zinsstag, J. (2009) Effectiveness of dog rabies vaccination programmes: comparison of owner-charged and free vaccination campaigns. Epidemiol. Infect., 1-10. doi:10.1017/S0950268809002386
Dürr, S.; Meltzer. M.I.; Mindekem, R.; Zinsstag, J. (2008) Owner Valuation of Rabies Vaccination of Dogs, Chad. Emerging Infectious Diseases 14: 10, 1650-1652.
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