A scrub hare, one of many wild species of rabbit affected by Rabbit Haemorrhagic Disease (RHD). Photo for illustration: iStock
A previously unknown disease wreaking havoc among wild hare and rabbit species in the Northern and Western Cape has been identified.
The Department of Agriculture, Land Reform and Rural Development (DALRRD) confirmed on Thursday that the outbreak has been identified as Rabbit Haemorrhagic Disease (RHD).
The Endangered Wildlife Trust (EWT) raised the alarm this month, with the first death of a scrub hare reported in October in the Sutherland area in the Northern Cape.
Since then, the disease has spread rapidly, as far as Springbok and Fraserburgh more than 500km away, to the Montague-Laingsburg area in the Western Cape.
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The most recent deaths of wild hares were reported to EWT in the Merweville and Beaufort West regions. The disease has also affected domestic rabbits in Cape Town and surrounding areas.
Field investigations involving state and private veterinarians, and the Department of Forestry, Fisheries and the Environment, saw post-mortems conducted and samples collected to confirm the cause of the wild hare and rabbit die-offs.
Diagnostic tests conducted at the Onderstepoort Veterinary Research Laboratory confirmed the causes of death as RHD.
Although the disease has been identified, its presence in South Africa is concerning.
DALRRD said it was not yet clear how the disease entered the country, as the importation of rabbits and hares is not allowed.
Investigations are currently underway to determine whether illegal importation could be the source of the presence of RHD.
As this is the first time RHD has ever been detected in South Africa, a vaccine is not yet available. And the only way to control RHD in rabbitries is to vaccinate as many rabbits and hares as possible.
Biosecurity measures are integral, and can be implemented with relative ease among rabbits kept in domestic settings.
But instilling these measures in wild populations is more difficult. Collecting carcasses, which could be major sources for viral spreading, is another concern.
The DALRRD said the virus appears to be “highly resistant and stable, even when exposed to harsh environmental conditions.”
“The occurrence of RHD in the Karoo is therefore of great concern, as our indigenous red rock rabbit, endangered riverine rabbot and hare species are highly susceptible to this disease,” DALRRD spokesperson Reggie Ngcobo said in a statement.
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RHD is a disease is a calcivirus of the genus Lagovirus. According to a 2012 journal entry in Veterinary Research, RHD was first detected in China in 1984, and has since spread rapidly around the world.
In less than one year, 140 million domestic rabbits were killed in China, and the disease spread over an area of 50 000km2.
Rabbit fur imports from China saw Korea hit next, after which it appeared in Italy in 1986.
Only North Africa has experienced RHD outbreaks on the continent.
In Australia and New Zealand, where rabbits were seen as pests, the RHD virus was purposefully introduced for biocontrol.
RHD causes acute necrotising hepatitis, a toxic and sudden liver injury. The virus also causes organs such as lungs, heart and kidneys to haemorrhage.
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Of particular concern is the effect the disease could have on the critically endangered riverine rabbit (Bunolagus monticularis), an elusive species endemic to the central Karoo region.
Riverine rabbits are found in dense patches of riverine bush, and are the only indigeous burrowing rabbit in Africa. Habitat loss has pushed the species to the brink of extinction, with two-thirds of its surroundings destroyed.
As of 2016 when the IUCN (International Union for the Conservation of Nature) last assessed the decreasing population, there were an estimated 157 to 207 mature individuals left.
EWT drylands conservation programme manager Johan du Plessis told The Citizen the organisation was “very concerned”, especially because the direct impact on riverine rabbits is unknown.
“The virus has historically caused high mortality rates in other countries in both domestic rabbits and wild hares and rabbits. As such, it could also have a devastating impact on riverine rabbits.”
Du Plessis said although the existence of a vaccine was good news, it was not yet known how it would be administered, if at all, in wild populations.
He said the disease can be easily transferred by animals, people, and even food and water sources.
The DALRRD is appealing to members of the public, land and pet owners to urgently report any dead or dying rabbits or hares, wild or domestic, to their nearest state veterinarian for investigation.
A complete list of state veterinarians across the country can be accessed by clicking here.
Any contaminated surfaces and clothing must be washed with bleach.
Riverine rabbit deaths can also be reported to the EWT, along with a photograph.
Landowners and farmers can report hare and rabbit deaths to ewt@ewt.org.za.
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