In natural ecosystems, the deadly canine distemper virus can jump between species and thrive, thereby threatening vulnerable animal populations, according to findings of a recently published study.
Canine distemper, a viral disease that’s been infecting the famed lions of Tanzania’s Serengeti National Park, appears to be spread not only by dogs but by multiple animal species, an international team of scientists has concluded. In their study, published online before print on 20 January in the journal Proceedings of the National Academy of Sciences, they say domestic dogs are no longer the primary source of the transmission of the disease to lions and that wild carnivores may contribute as well.
Dogs and beyond
In 1994, a mysterious neurological ailment wiped out 30 percent of the lion population in the Serengeti, one of the largest wildlife regions in the world. Scientists determined it was canine distemper, a disease previously thought to infect only dogs, coyotes and a small number of other mammals.
Evidence revealed the lions had contracted distemper from dogs living in villages and settlements nearby. A domestic dog vaccination campaign was launched to curb the infection’s spread. It worked — among dogs, at least.
After analysing three decades of blood serum data collected from lions and domestic dogs, the study’s researchers discovered that the virus continues to circulate in the lion population while significantly declining among dogs.
The dog’s role in spreading the disease appears to be shrinking, conclude the paper’s authors, a collaboration of veterinarians, disease ecologists, epidemiologists and mathematical biologists.
“Domestic dog populations immediately surrounding the Serengeti National Park are not the sole driver of canine distemper infections in lions, and its persistence is likely to involve a larger multi-host community,” the scientists write in their study.
Other big cats are threatened by the canine distemper virus as well. Especially the vulnerable wild Amur tiger population turns out to be exposed to the virus and become diseased with one of the worrying symptoms that the cats seem to lose their fear of man, which increases the chance of human-tiger conflict and leaves them easy prey for poachers.
Risk of outbreaks
Other species, including hyenas and jackals, are probably transmitting the disease and keeping it looming in the wild, the authors say. Consequently, outbreaks among lions and other already-threatened animals could occur at any time.
Researchers say more work is necessary to identify which species spread distemper and what triggers the spillovers. For example, previous analyses suggest that an infected hyena or other carnivore feeding on a carcass can disperse the virus through mucus secretions to other predators at the same site.
“A better understanding of canine distemper virus and its dynamics in the wild is necessary to better monitor and control the disease among lions and other threatened animals,” said Felix Lankester, the Tanzania-based veterinary researcher.
(Source: Washington State University press release, 28.01.2015)
