Potential for rabies control through dog vaccination in wildlife-abundant communities of Tanzania.

Katie Hampson,Lauren Ancel Meyers,Jeffrey P Townsend,Sarah Cleaveland,Meagan C Fitzpatrick,Alison P Galvani

doi:10.1371/journal.pntd.0001796

Abstract

Canine vaccination has been successful in controlling rabies in diverse settings worldwide. However, concerns remain that coverage levels which have previously been sufficient might be insufficient in systems where transmission occurs both between and within populations of domestic dogs and other carnivores. To evaluate the effectiveness of vaccination targeted at domestic dogs when wildlife also contributes to transmission, we applied a next-generation matrix model based on contract tracing data from the Ngorongoro and Serengeti Districts in northwest Tanzania. We calculated corresponding values of R 0, and determined, for policy purposes, the probabilities that various annual vaccination targets would control the disease, taking into account the empirical uncertainty in our field data. We found that transition rate estimates and corresponding probabilities of vaccination-based control indicate that rabies transmission in this region is driven by transmission within domestic dogs. Different patterns of rabies transmission between the two districts exist, with wildlife playing a more important part in Ngorongoro and leading to higher recommended coverage levels in that district. Nonetheless, our findings indicate that an annual dog vaccination campaign achieving the WHO-recommended target of 70% will control rabies in both districts with a high level of certainty. Our results support the feasibility of controlling rabies in Tanzania through dog vaccination.

Highlights

Rabies is a viral encephalitic disease, transmitted to humans primarily from rabid animals
Vaccination coverage for only dogs might be insufficient in countries such as Tanzania, where wildlife has been shown to carry and transmit rabies
We developed a model parameterized with field data on rabies in dogs and wildlife from two districts of Tanzania, Ngorongoro and Serengeti

Summary

Introduction

Rabies is a viral encephalitic disease, transmitted to humans primarily from rabid animals. Domestic dogs account for more than 95% of human exposures. Canine vaccination has the potential to concomitantly prevent disease in humans [4,5,6,7]. Where domestic dogs are the reservoir hosts, canine vaccination has been shown to be an effective control strategy in many parts of the world [6]. Domestic dog vaccination has led to the elimination of canine rabies in Western Europe and the US [8,9] and to widespread control of the disease in Latin America [10]. There remains skepticism regarding the degree to which large-scale dog vaccination campaigns can control or eliminate dog rabies in the presence of abundant wildlife host species, and concern that coverage levels which have historically been sufficient for rabies control elsewhere might be insufficient in these settings [7]

Methods

Results

Discussion

Conclusion