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The “dog virus” that kills big cats?

Sunday 21st January 2018

 

That is how canine distemper (CDV) has been described in the past by uninformed journalists.

 I would urge all of you concerned with wildlife conservation to read this post carefully and gain a better understanding of this pernicious group of viruses that can best be characterized as an alarming and emerging threat to conservation of a great diversity of species.

 Have a look at this video  https://www.youtube.com/watch?v=uMEfvrXqrH4  of a lion infected with canine distemper. The animal has what is called a “grand mal” seizure – typical of CDV infection. Also clear is how easily the virus can be spread to other lions in the group – CDV is communicated via aerosol  - in this case via the copious saliva from the infected young male. Of the five lions in the group, four died.

For an overview of the disease, read this:

“Canine distemper is a highly contagious acute febrile disease caused by the canine distemper virus (CDV), which is a paramyxovirus closely related to the [human] measles and [bovine] rinderpest viruses. The disease has been known since at least 1760; it has a worldwide distribution, and occurs in a wide variety of terrestrial carnivores including Canidae (dog, fox, wolf, raccoon dog), Mustelidae (ferret, mink, skunk, wolverine, marten, badger, otter), Procyonidae (raccoon, coatimundi), Viverridae (palm civet), Ailuridae (red panda), Ursidae (bear), and large Felidae (lions, tigers, leopards, cheetahs), as well as a few other mammals such as Asian elephants and some primates.  Domestic and feral dogs are considered to be the main reservoir host species.  Closely related viruses cause a similar disease in seals (phocine distemper virus) and in porpoises and dolphins (cetacean morbillivirus).  CDV is a serious threat to endangered wildlife and this threat is expected to increase with increased encroachment of humans (along with their dogs) into undeveloped areas of the world.  Recent large outbreaks in nonhuman primates suggest the virus has adapted to these animals and that the potential exists for it to infect humans.”

We were recently reminded of concerns about this virus with a recent publication (2017, event occurred in 2015) attributing the death of a highly endangered Amur leopard (of which about 60 individuals remain….) to CDV.

Understandably, the authors of the article expressed considerable concern about the impact of this virus on small populations of endangered carnivores.

So focused are we on the threats of poaching and habitat loss that we have placed the threat of disease very low on the totem pole of issues to be addressed in overall conservation priorities of endangered species. How wrong this is. 

I was unfortunate enough to have encountered the effects of canine distemper on a diversity of wild carnivores while researching African wild dogs in Kenya’s  Masai Mara. A canine distemper outbreak occurred there among domestic dogs in 1990-1991, spread to jackals, bat-eared foxes, hyenas. Killed off all the wild dogs in the area – coming shortly after an outbreak of rabies that had already killed all members of a wild dog pack in 1989.

This outbreak spread to the neighbouring Serengeti National park in Tanzania, where over 1,000 lions died in 1994. Recent information indicates that the death of these lions might have been caused by a “variant” of the usual domestic dog strain prevalent in the region, raising even more concerns about the ability of CDV strains to mutate and - in the words of the authors of this article – result in “a greater complexity of CDV molecular epidemiology in multihost environments than previously thought”.

 

In other words, we must be very concerned about the potential negative effects of diseases in conservation programmes, especially those involving populations not capable of rebounding from significant mortality among an already small number of individuals? For such small populations, all threats should be evaluated and integrated in informed conservation initiatives – and surely some of the most important of those threats are posed by multihost viruses like “canine” distemper?


Youtube video credit:  Nikki Keyter

 

 

 


Add a comment | Posted by Chris Macsween at 18:25