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Amur Tigers Succumb to Canine Disease

Posted by Richard Conniff on October 21, 2013

Siberian tigerA week or two ago, I wrote about how feral dogs kill wildlife by direct attack, by stealing prey, and by spreading disease.  Now a report on the BBC says canine distemper is killing critically endangered Amur tigers in the Russian Far East.

The article quotes one author of a new paper in mBio on the epidemic:  “When you’re talking about four to five hundred animals and you’re losing reproductive females and their offspring, the overall impact on populations ishuge.”

Another virologist comments: “Because they are such tiny populations even relatively small mortality events can seriously harm their genetic  diversity and this might just be enough to push them over the edge.”

The BBC story by virologist Jonathan Bell also fills in some of the history of wildlife outbreaks caused by feral dogs:

Canine distemper virus (CDV), a relative of the human measles virus, was first described in dogs, and infection causes fatal pneumonia and encephalitis (inflammation of the brain).

But this virus is incredibly promiscuous and can infect jump into a variety of different animals – usually with catastrophic effects.

Two suspected CDV outbreaks, the first in 1988 and a second in 2000, killed thousands of Baikal then Caspian seals.

The virus has also ripped through Africa, with fatal outbreaks in silver-backed jackals and bat-eared foxes and catastrophic die-offs in wild dog populations that continue to this day.For years, cats were thought resistant to CDV. Yes, domestic cats could be infected in the laboratory, but this was inefficient and the virus was unable to pass from one animal to another.

A massive demise in 1994 of African lions living in the Serengeti national park in Tanzania showed that this was fallacy. This population of closely monitored lions succumbed to CDV. Whilst only 34 lion deaths were documented during the outbreak, this was only the tip of the iceberg.

Before CDV struck, the lion population numbered 3,000, but afterwards this had fallen by a third. In the same outbreak, countless hyenas, bat-eared foxes and leopards also perished.

Add to this the recent report of infection of large numbers of South American jaguar and it is evident that this virus has little, if any respect for the so-called species barrier – the unique inherent host factors and properties that prevent viruses from jumping from one species to another.

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