Have Domestic Dogs Infected Kgalagadi's Lions?

On October 2009, four lions died of canine distemper virus (CDV) in the Kgalagadi Transfrontier Park (KPT).

While four lion deaths are not particularly significant, the vet alert kicks in when these deaths are attributed to a disease more commonly found in domestic dogs than wildlife. This is only the second recorded outbreak of CDV in free-ranging lions in Africa.

In 1994, the Serengeti conservation area lost an estimated 30 percent of its lion population (1000 lions) to an epidemic outbreak of CDV.

It was an alert KPT tourist that video captured and then reported a young male lion's abnormal behaviour and signs of sickness that set the CDV detection wheels in motion. Spotted at the Houmoed water hole, about 25 kilometres from Tweerivieren Rest Camp, the lion seemed to have suffered from seizures. Park rangers saw the lion the following day (Saturday) and found the carcass 24 hours later.

The unusual nature of the death and other symptoms urged the South African National Parks (SANParks) Veterinary Wildlife Service section to alert the sate veterinary department immediately on Monday. A state vet technician conducted a post mortem that same afternoon, but the results were inconclusive, as the carcass had decomposed too much.

In the following week, a second young male lion, from a different pride and showing similar signs of convulsions, was spotted at the Thirteenth water hole, 60 kilometres north of the Tweerivieren camp towards Mata Mata. It died soon after. A third lion, a young female and a member of the first pride, died in the vicinity of the Aucterlonie waterhole. A full post mortem was done in Upington within eight hours. The following day, Friday October 23, an adult lioness died at the same waterhole.

The next week, blood tests and other samples were collected from five animals of the first pride, while the rest of the pride was closely observed for a few hours. The animals appeared to be in relatively good condition, but an adult male and young lion showed symptoms that prompted the team to get up close and personal for more blood and swabs to add to the growing sample collection.

On October 30, the vets diagnosed CDV and ruled out other suspected causes such as poisoning, rabies or anthrax.

CDV is a highly contagious, often fatal, viral disease and closely related to the measles and rinderpest viruses. It is believed to occur mainly in domestic dogs with "spill-over into wild carnivores occurring from close contact around shared carcasses, and other contact," says Dr Danny Govender, Disease Ecologist, SANParks who headed the task team with fellow SANParks vet, Dr David Zimmermann.

The virus affects the respiratory, gastrointestinal, and central nervous systems and infected animals usually transmit the disease through direct contact with bodily fluids, which can also be airborne. Clinical symptoms include abnormal behavior of drinking water at the heat of the day, listlessness and lying in the midday sun. Neurological signs include twitching, tilting of the head, and seizures.

It is believed the Kgalagaldi lion population has developed some resistance against the virus by developing anti-bodies after previous exposures in the early 90s, notably in the prides that stay closer to the boundaries of the park, and possibly, having had contact with domestic dogs. In addition, the low lion and related prey densities, as well as the large territories of the various prides appear to slow down the spread of the disease in the KPT, compared to the rapid spread in the Serengeti in the mid 90s.

"The progression of the disease will be closely monitored," says Dr Govender. Logistical difficulties, problems with the available vaccine and the possibility of increasing the risk between lions and domestic animals have ruled out the vaccination of the KPT lions. However, an intensified rabies and CDV vaccination campaign on the park borders, especially targeting domestic dogs, is imperative. This outbreak highlights "the complexity of managing diseases at this interface and that even big, open ecosystems, such as the Serengeti and the KTP, are not immune to the impacts of human encroachment and fragmentation."

By Lynette Strauss

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