The highly contagious distemper virus not only affects dogs, but also all kinds of other carnivores. This now includes tigers and leopards in Nepal, as blood analyzes reveal. For the already endangered animals with small, isolated populations, the virus could quickly have devastating consequences. The scientists suspect that at least the leopards become infected when hunting street dogs. They recommend monitoring big cat populations even more closely.
Canine distemper virus is distributed worldwide and can affect a variety of carnivorous predators, including dogs, wolves, and foxes. Mortality is up to 95 percent. The disease usually progresses in three phases. After initial fever attacks, the infected animals usually suffer from shortness of breath and gastrointestinal problems. Eventually, disorientation, seizures, and often death follow. While dogs can be vaccinated against the virus early in life, protecting wild animals is a lot more difficult.
Distemper also in big cats in Nepal
Big cats like tigers and leopards can also contract distemper. So far, corresponding cases from Russia, India and Indonesia have been known, but the disease has apparently continued to spread. This is shown by blood analyzes of 48 Nepalese tigers and leopards carried out by a team led by Jessica Bodgener from Cornell University in New York. The blood samples were taken between 2011 and 2021 as part of Nepalese wildlife management. They provide information on whether the animals have ever come into contact with the distemper virus.
And indeed: About a tenth of the tigers (three out of 28) and a third of the leopards (six out of 20) had antibodies against the virus in their blood. You must therefore have been infected with distemper before. Some of the animals that tested positive were apparently even at the time the blood was taken. According to the wildlife managers, they had lost a lot of weight, had difficulty breathing, were disoriented or showed unusually little fear of humans. Three of these conspicuous animals died within a week after the blood was taken and could not be saved even with infusions and medication.
Street dogs as a possible virus origin
But where did the big cats get infected? At least as far as the cases among the leopards go, the scientists have a guess. “We already know that the virus circulates in the Nepalese dog population and that leopards eat dogs frequently,” says Bodgener. The distemper virus could have jumped over in this way. However, since tigers are not known to eat street dogs, other host animals must be around. Jackals or civet cats are suspected. Future gene analyzes should bring more clarity about the origin of the virus and enable more effective protection of the big cats.
However, it is not only about the survival of individual tigers and leopards, but about the continued existence of entire populations. Although tiger populations in Nepal have recovered strongly in the past decade, the animals live separately from each other. The scientists warn that the distemper virus can be particularly devastating in such small, isolated populations. The leopard populations, on the other hand, are likely to have been declining for a long time, even without distemper, estimate Bodgener and her team. If the disease spreads further among them, the consequences would be all the more serious. The scientists advise monitoring both big cats even more closely for typical signs of disease, using molecular analysis to find the origin of the virus and connecting the fragmented populations to wildlife corridors to prevent local extinction.
Source: Cornell University; Article: Pathogens, doi: 10.3390/pathogens12020203