The Prime Minister’s announcement that tiger numbers have increased in the country may be good news. But the loss of habitat, a decline of prey and poaching continues to be a threat to tigers’ survival. Along with these, a potential virus — Canine Distemper Virus (CDV) — that can be transmitted from CDV-infected dogs living in and around wildlife sanctuaries has started to raise concern among wildlife biologists.
Canine distemper is a contagious and serious disease caused by a virus that attacks the respiratory, gastrointestinal and nervous systems of puppies and dogs.
Risk of disease transfer
A recent study published in Threatened Taxa notes that 86% of the tested dogs around Ranthambhore National Park in Rajasthan carried CDV antibodies in their bloodstream. This means that the dogs are either currently infected or have been infected sometime in their life and have overcome the disease. This finding points out that there is an increased risk of disease transfer from the dogs to tigers and leopards that live in the park.
Last year, over 20 lions from the Gir forest succumbed to the viral infection and now a guideline has been prepared by the National Tiger Conservation Authority to prevent the spillover of the disease to wild animals.
“The main aim should be to vaccinate the free-ranging and domestic dogs in the area around national parks. A lot of NGOs have started started animal birth control programmes. They need more support from the government,” says Dr. Jimmy Borah, Consultant, Species Conservation and Law Enforcement, Panthera, and the corresponding author of the paper. “The disease needs to be recognised and more targeted studies need to be initiated to collect baseline data on CDV from wherever they are reported from in wild carnivores. Understanding the role of domestic animals as contributors to a local CDV reservoir is imperative precursor in considering control measures.”
The study was done from July to August 2015 when the team visited villages (in a 4 km radius) around the Ranthambhore National Park and collected blood samples from over 100 dogs. The results showed that 86% of the studied dogs had CDV antibodies in their blood. These dogs wander into the forest along with the humans, and there have been cases where leopard have hunted these dogs. “Studies from Russia and Africa have shown that small, isolated wildlife populations are more susceptible and when the virus transmits from one species to another the disease manifestation is worse,” adds Dr. Borah.
“The easy way out is prevention. Managing any disease in a wildlife population is extremely difficult. Most dogs are free ranging and not owned by any particular person in the village. The government should take the initiative to vaccinate the dogs around wildlife sanctuaries in the country. This would be a good time to vaccinate against rabies as well. It is an investment that requires time and effort but increasing herd immunity will reduce chances of disease spillover to wildlife,” says Nadisha Sidhu, first author of the work. She was a researcher with the World Wide Fund for Nature-India when the work was done and is now a consultant for Ashoka Trust for Research in Ecology and the Environment, Bengaluru.
Ms. Sidhu says there were only a few CDV suspected cases in India when she started her work in 2015, and so was considered not important. But with the CDV confirmed deaths of lions in Gir, more attention has been drawn to the disease. She hopes more studies are conducted to get countywide data on the disease prevalence so that necessary prevention guidelines can be laid out.