A team of Russian veterinary colleagues and health experts from the Wildlife Conservation Society's Bronx Zoo are collaborating to understand more about how the virus is affecting the species, helping conservationists formulate health measures to counter this latest threat to the world's largest cat.
The team of health experts, working at the Wildlife Conservation Society's wildlife health centre at Bronx Zoo, used histology along with PCR and DNA sequencing to confirm and characterise the infection in two wild Siberian tigers from the Russian Far East.
This diagnosis provides long-awaited genetic confirmation of the fact that distemper is affecting wild tigers, which WCS and Russian colleagues first documented in 2003.
Tiger wandered into village looking for an easy meal
Last year a tigress known as Galia - studied by WCS researchers for eight years in Sikhote-Alin Biosphere Reserve in the Russian Far East - walked into the village of Terney, displaying abnormal neurologic signs. She was seemingly unfazed by the new surrounding, appeared gaunt, and was searching for dogs as an easy meal. The tiger was shot by local police after several capture attempts failed.
In November 2003, a similar event occurred when an otherwise healthy looking wild tigress walked into the village of Pokrovka in Khabarovski Krai. WCS staff immobilised the animal and worked with local Russian veterinarian Evgeny Slabe in treating the tiger, which later died in captivity. Samples for the diagnosis of distemper were collected only from these two animals.
But several other examples of tigers entering villages or stalling traffic on major roadways - behaviour possibly indicative of distemper - have been reported in recent years.
Already known to kill lynx and bobcats
Distemper is found worldwide in domestic dogs and has caused infection and death in wild species such as lynx and bobcats in Canada, Baikal seals in Russia, lions in the Serengeti ecosystem in Africa, and raccoons and the endangered black footed ferret in the United States.
‘With all the threats facing Siberian tigers from poaching and habitat loss, relatively little research has been done on diseases that may afflict tigers,' said Dale Miquelle, WCS Director of Russia programmes. ‘There are no records of tigers entering villages and behaving so abnormally before 2000, so this appears to be a new development and new threat. Understanding whether disease is a major source of mortality for Siberian tigers is crucial for future conservation efforts.'
Anatoly Astafiev, director of Sikhote-Alin Reserve, said: ‘We have seen a fall in tiger numbers within our reserve, so it is very important to know that at least one of the causes is a recognisable disease, something we may be able to address and potentially prevent.'
Canine distemper is controlled in domestic dogs through vaccination. In Africa, massive vaccination campaigns of dogs in villages surrounding the Serengeti appear to have been effective in reducing the disease's impact on lions.