Saving Siberian Tigers Through Vaccination

Researchers from Cornell Wildlife Health Center, Wildlife Conservation Society, and the University of Glasgow reveal that canine distemper virus (CDV) in Siberian Tigers in the wild is contributed by local wildlife species and not from domestic dogs as previously believed. The study team also proposed injectable vaccination as an option to control the spread of the CDV virus among Siberian Tigers. 

Canine Distemper Virus (CDV) in Siberian Tiger 

Siberian tigers are so rare that there are less than 550 them in the Russian Far East and China. 

The canine distemper virus poses serious illness in domestic dogs and other carnivores—even threatened species like the Siberian tiger or the Amur tiger.

Symptoms of CDV in Siberian tigers in 2001 showed that the tigers became underweight, weak, disoriented, and became incapable of hunting. At least four cases of the tigers have to be put down as they wandered into towns in search of food. A CDV infected mother left her three-week-old cub, which eventually died of starvation. 

CDV is a fatal viral disease that shows a wide range of symptoms such as fever, diarrhea, labored breathing, dehydration, and seizures. It is believed that Siberian tigers got the disease from eating infected carnivores in the Russian wilderness. 

Domestic dogs are believed to be the primary source of the canine distemper virus. Recently, however, a study published on November 23 in the Proceedings of the National Academy of Sciences by a study team from the Cornell Wildlife Health Center headed by Martine Gilbert revealed that other local wildlife is the primary CDV source transmission to the tigers, not the domestic dogs. 

Gilbert said that knowing the distemper virus's primary source is crucial in designing measures to minimize the virus's impact on the Siberian tiger's conservation. 

READ: WATCH HERE: Footage of the Last Tasmanian Tiger in Captivity

Study methodology 

The study team studied several samples from domestic dogs, tigers, and other wild carnivores to develop a picture of CDV epidemiology in the Russian Far East's tiger's habitat. They compared viral genetic sequence data and antibodies to analyze the pattern of exposure in each population. 

According to study co-author Dr. Nadezhda Sulikhan, a researcher from the Federal Scientific Center of East Asia Terrestrial Biodiversity, the Siberian tigers are the taiga forest has supported a high diversity of 17 carnivore species.

The study findings also revealed that more abundant small-bodied species like martens, badgers, raccoon dogs are the "most important contributors to the CDV reservoir."

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The option of vaccination

The study team found that controlling CDV in the abundant wild carnivore population is impossible as there are no CDV oral vaccines that could be given to the wild through baited food. 

The difficult but viable option is to use an injectable vaccine on tigers. 

The study results indicate that serum from tigers vaccinated in captivity was able to neutralize the strain of CDV that was detected in Russia. A computer model that the study team developed showed that vaccinating even two tigers per year could reduce the Siberian tiger's risk of extinction from CDV significantly.

Vaccination as a valuable conservation strategy 

The study team asserts that vaccination can be a valuable conservation strategy. Habitat destruction, poaching, and climate change have caused a fragmented wild population. Infectious disease like CDV makes endangered species like Siberian Tiger vulnerable to extinction. 

Taking actions like vaccination shows that CDV in Siberian tigers may now be addressed: a rare piece of good news for the tiger conservation community, Sarah Cleaveland, professor of comparative epidemiology at the University of Glasgow and a contributor to the study said.

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