Antibody response to Raboral VR-G® oral rabies vaccine in captive and free-ranging black-backed jackals (Canis mesomelas).

Katja N Koeppel,Peter Geertsma,Ockert L Van Schalkwyk,Peter N Thompson,Brian F Kuhn

doi:10.4102/ojvr.v89i1.1975

Abstract

Rabies is a zoonotic disease that remains endemic in large parts of southern Africa because of its persistence in wildlife and domestic dog vectors. The black-backed jackals (Canis mesomelas) is primarily the wildlife vector responsible for rabies outbreaks in northern parts of South Africa. Two trials were carried out to investigate antibody responses to the oral rabies vaccine Raboral V-RG® in black-backed jackals under captive and free-ranging conditions. In captive jackals 10/12 (83%; 95% confidence interval [CI]: 52% – 98%), seroconverted after single oral vaccination. Nine captive jackals had protective antibody titres (> 0.5 IU/mL) at 4 weeks (median: 2.1 IU/mL; inter quartile range [IQR]: 0.6–5.7) and 10 jackals had at 12 weeks (median: 3.5 IU/mL; IQR: 1.5–8.3) and three maintained antibody titres for up to 48 weeks (median: 3.4 IU/mL; IQR: 2.0–6.3). Four sites were baited with Raboral V-RG® vaccine for wild jackals, using fishmeal polymer and chicken heads. Baits were distributed by hand or from vehicle at three sites in north-eastern South Africa, with an average baiting density of 4.4 baits/km2 and at one site in central South Africa, at 0.12 baits/km2. This resulted in protective antibody titres in 3/11 jackals (27%; 95% Cl: 6–61) trapped between 3 and 12 months after baiting in north-eastern South Africa, compared with 4/7 jackals (57%; 95% Cl: 18–90) trapped after 3–18 months in central South Africa. This study shows the potential utility of oral rabies vaccination for the control of wildlife-associated rabies in north-eastern and central South Africa, but extensive studies with wider distribution of bait are needed to assess its potential impact on rabies control in wild jackals.

Highlights

Rabies is an important zoonotic disease caused by a rhabdovirus belonging to the Lyssavirus genus
Of the 12 jackals, 10 that received oral rabies vaccine seroconverted at 12 weeks after oral rabies vaccination, resulting in an estimated seroconversion proportion of 83% (95% confidence interval [CI]: 0.52–0.98) (Table 1)
This study has shown that the Raboral V-RG® oral rabies vaccine results in adequate antibody titres for up to 12 months after vaccination in captive black-backed jackals

Summary

Introduction

Rabies is an important zoonotic disease caused by a rhabdovirus belonging to the Lyssavirus genus. It is a single-stranded, negative-sense RNA virus causing fatal encephalitis in domestic animals, humans and wildlife (Swanepoel et al 1993). In most parts of Africa, rabies is associated with domestic dogs and wildlife species have not been considered important vectors (Wandeler 1993) until more recently when it was established that jackals can sustain rabies infection without outside introductions from domestic dogs (Zulu, Sabeta & Nel 2009). The first reported case of rabies in South Africa was in the Cape Province in 1882 from an infected dog that was brought in from England; it took two years to control the outbreak in dogs (Swanepoel et al 1993). The disease continued to spread southwards and westwards in South Africa (Brückner, Hurter & Boshoff 1978)

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