Scientists in South Africa say they have identified an outbreak of rabies in seals that is believed to be the first time the virus has spread in sea mammals.
At least 24 Cape fur seals that were found dead or euthanized in various locations on South Africa’s west and south coast had rabies, state veterinarian Dr. Lesley van Helden said.
Rabies, which affects mammals and can be passed to people, is almost always fatal once symptoms appear. Rabies spreads via saliva, usually through bites but also sometimes when animals lick and groom each other.
The virus has long been seen in wild animals such as raccoons, coyotes, foxes, jackals and in domestic dogs. But it had never been recorded spreading among marine mammals, van Helden and other experts said this week.
The only other known case of rabies in a sea mammal was in a ringed seal in Norway’s Svalbard islands in the early 1980s. That seal had likely been infected by a rabid arctic fox, researchers said, and there was no evidence of rabies spreading among seals there.
Authorities in South Africa first discovered rabies in Cape fur seals in June after a dog was bitten by a seal on a Cape Town beach. The dog became infected with rabies, prompting rabies tests on brain samples from 135 seal carcasses that researchers had already collected since 2021. Around 20 new samples also were collected and more positives have come back on subsequent tests.
Scientists are trying to work out how rabies was passed to the seals, whether it is spreading widely among their large colonies and what can be done to contain it.
“It’s all very, very new,” said Greg Hofmeyr, a marine biologist who studies seals in South Africa. “A lot of research is required … there are a lot of unknowns here.”
There are approximately 2 million seals migrating back and forth between South Africa, Namibia and Angola along Africa’s south and west coast. The most likely possibility, van Helden said, is that rabies was first passed onto seals by jackals in Namibia, where the wolf-like animals hunt seal pups on the coastline.
