As the world's tiger population contracts, these cats are not only being driven to extinction by habitat loss and illegal hunts - they're being dealt a blow on a microbial level, too.
A spreading disease related to measles called canine distemper virus affects mammalian guts, lungs and nervous tissue (though not those of humans or domestic cats). In dogs, the mortality rate can reach up to about 50 percent, which is why owners should ensure pet dogs receive a distemper vaccine.
Wild tigers don't have the luxury of vaccinations or regular visits to the vet. When the big cats prey on sick dogs or other carnivores, they run the risk of becoming infected with the disease. Researchers from conservation groups Panthera and Wildlife Conservation Society, as well as U.K. veterinarians and other scientists, calculated that as the disease spreads through Amur tigers in Russia, this subspecies is up to 56 percent more likely to go extinct in the next half century.
Small groups of 25 individuals in the Sikhote-Alin Biosphere Zapovednik are at particular risk, the scientists noted in the journal PLOS ONE. Even a low-risk disease scenario ups the tigers' odds of extinction in this area by 6 percent.