Zimbabwe (Mansvelt 1956). Dog destruction and vaccination campaigns in
South Africa were unsuccessful in eradicating the disease and the virus established
itself in the local dog population, causing a low number of sporadic cases in dogs in
the years that followed. The infection also spilled over into Black-backed Jackals
(Canis mesomelas) and cattle in the area, resulting in attempts to control the disease
by poisoning 3900 jackals between 1951 and 1953 (Mansvelt 1956). There was
subsequently no evidence that the virus had become established in the wildlife
population. It is possible that this was because poisoning after the outbreak was
rapid enough to prevent establishment of the disease in the jackal population.
However, rabies was probably reintroduced near Messina (now Musina), causing
a large outbreak in the 1970s (Fig. 10.1). It was quickly realised that further attempts
to control the outbreak by poisoning of jackals were futile. Once rabies becomes
endemic in a population, culling strategies for control are unsuccessful, as population numbers are able to increase too quickly after culling (Swanepoel 1995). The
focus on control was therefore shifted to the vaccination of dogs in the area, an
approach which has been used ever since considering that dog and jackal rabies
remains a problem in the area to this day. The virus spread to Mozambique by 1952
and from there to Swaziland, KwaZulu-Natal and the Eastern Cape. Sporadic cases
of rabies were seen in South African Bat-eared Foxes (Otocyon megalotis) from
1955, but case numbers rapidly increased in the 1970s when the virus apparently
spread to the Northern and Western Cape (Swanepoel 1995).
Molecular analysis of rabies viruses in South Africa shows that jackals and
bat-eared foxes have become maintenance hosts for their own biotypes of canid
rabies (Sabeta et al. 2007). Biotypes from dogs, jackals and bat-eared foxes are more
closely related to each other and to rabies biotypes from Europe than mongoose
rabies, which is distantly related to both the South African canine and European
biotypes (von Teichman et al. 1995; Coetzee and Nel 2007). This indicates that
jackal and bat-eared fox biotypes share a common lineage with introduced dog
rabies, while mongoose rabies evolved separately and is much older in South Africa.
Jackals and bat-eared foxes both have characteristics that have enabled the canid
rabies virus to establish itself in their populations. For instance, bat-eared foxes are
highly sociable, have overlapping territories and often share dens with other family
groups of bat-eared foxes and even other species. They live in close contact, sleeping
close together and often engaging in mutual grooming that involves licking of each
other’s faces (Nel 1993). Rabies is therefore transmitted easily by providing many
opportunities for bat-eared foxes to encounter other potentially rabid animals as well
as infect each other through contact with saliva. Rabies in South African wildlife
appears to be seasonal, based on increased contact between animals of the same
species in times of mating or dispersal of young animals to find their own territories
(Swanepoel 1995). However, other effects such as climate change and drought can
influence this. In the Swartland area of the Western Cape, bat-eared fox numbers
fluctuate vastly from year to year, with all bat-eared foxes in an area seeming to
suddenly disappear, only for the population to recover within a few years (J. van
Deventer, pers. comm. 2016). Whether or not these population crashes are caused by
rabies is unknown. However, this seems likely given that in areas in which the
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L. van Helden et al.
South Africa were unsuccessful in eradicating the disease and the virus established
itself in the local dog population, causing a low number of sporadic cases in dogs in
the years that followed. The infection also spilled over into Black-backed Jackals
(Canis mesomelas) and cattle in the area, resulting in attempts to control the disease
by poisoning 3900 jackals between 1951 and 1953 (Mansvelt 1956). There was
subsequently no evidence that the virus had become established in the wildlife
population. It is possible that this was because poisoning after the outbreak was
rapid enough to prevent establishment of the disease in the jackal population.
However, rabies was probably reintroduced near Messina (now Musina), causing
a large outbreak in the 1970s (Fig. 10.1). It was quickly realised that further attempts
to control the outbreak by poisoning of jackals were futile. Once rabies becomes
endemic in a population, culling strategies for control are unsuccessful, as population numbers are able to increase too quickly after culling (Swanepoel 1995). The
focus on control was therefore shifted to the vaccination of dogs in the area, an
approach which has been used ever since considering that dog and jackal rabies
remains a problem in the area to this day. The virus spread to Mozambique by 1952
and from there to Swaziland, KwaZulu-Natal and the Eastern Cape. Sporadic cases
of rabies were seen in South African Bat-eared Foxes (Otocyon megalotis) from
1955, but case numbers rapidly increased in the 1970s when the virus apparently
spread to the Northern and Western Cape (Swanepoel 1995).
Molecular analysis of rabies viruses in South Africa shows that jackals and
bat-eared foxes have become maintenance hosts for their own biotypes of canid
rabies (Sabeta et al. 2007). Biotypes from dogs, jackals and bat-eared foxes are more
closely related to each other and to rabies biotypes from Europe than mongoose
rabies, which is distantly related to both the South African canine and European
biotypes (von Teichman et al. 1995; Coetzee and Nel 2007). This indicates that
jackal and bat-eared fox biotypes share a common lineage with introduced dog
rabies, while mongoose rabies evolved separately and is much older in South Africa.
Jackals and bat-eared foxes both have characteristics that have enabled the canid
rabies virus to establish itself in their populations. For instance, bat-eared foxes are
highly sociable, have overlapping territories and often share dens with other family
groups of bat-eared foxes and even other species. They live in close contact, sleeping
close together and often engaging in mutual grooming that involves licking of each
other’s faces (Nel 1993). Rabies is therefore transmitted easily by providing many
opportunities for bat-eared foxes to encounter other potentially rabid animals as well
as infect each other through contact with saliva. Rabies in South African wildlife
appears to be seasonal, based on increased contact between animals of the same
species in times of mating or dispersal of young animals to find their own territories
(Swanepoel 1995). However, other effects such as climate change and drought can
influence this. In the Swartland area of the Western Cape, bat-eared fox numbers
fluctuate vastly from year to year, with all bat-eared foxes in an area seeming to
suddenly disappear, only for the population to recover within a few years (J. van
Deventer, pers. comm. 2016). Whether or not these population crashes are caused by
rabies is unknown. However, this seems likely given that in areas in which the
254
L. van Helden et al.