Emergency response using oral rabies vaccination of dogs -field data from Namibia demonstrate high efficiency

Abstract

Dog-mediated rabies is responsible for tens of thousands of human deaths annually, and in resource-constrained settings, vaccinating dogs to control the disease at source remains challenging for various reasons. Currently, rabies elimination efforts rely on mass dog vaccination by the parenteral route. While oral rabies vaccination (ORV) of dogs is primarily considered a tool to increase herd immunity, particularly by targeting free-roaming and stray dogs, here, we are showcasing an ORV-only approach as an emergency response model. Using a third-generation vaccine and a standardized egg-flavored bait, we assessed the effectiveness and vaccination under field conditions in the Zambezi region of Namibia. During this trial, with four teams and within four working days, 3097 dogs were offered a bait, of which 88,0% were considered vaccinated. Teams managed to vaccinate, on average, over 20 dogs/h, despite using a door-to-door vaccination approach. The favorable results both in terms of bait acceptance and successful vaccination as well as field applicability and effectiveness further support the great potential of ORV in dog rabies control programmes.

Keywords: Africa; Dogs; Namibia; Oral vaccination; Rabies; SPBN GASGAS.

Fig. 1

Location in Africa and map of Namibia and the Zambezi region highlighted (red). (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)

Fig. 2

A) Distribution of baits offered at four days during urban vaccinations. Dogs considered vaccinated are displayed as green dots (N = 624), dogs with an unknown status are displayed blue (N = 98) and non-vaccinated dogs (N = 28) are displayed as black dots. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)

Fig. 3

Display of vaccinations and human settlements in the Zambezi-region, overlayed with a 4x4km grid. Insert: Estimation of vaccination coverage in grid cells with ORV using population counts from High Resolution Population Density Maps and a human:dog ratio of 5.

Fig. 4

Vaccination assessment (A) and team efficiency (B) for ORV stratified per location, i.e. the rural Zambezi region where door-to-door (D2D) was performed, and urban Katima Mulilo, were free-roaming dogs were baited directly from the car. Additionally, the per team performance in Oshana is shown, where vaccines were give parenterally at central points (CP).

Fig. 5

Display of the dynamic range of costs per dog vaccinated depending on the number of dogs vaccinated per team and day, and the use of oral vaccination compared to parenteral vaccination.