The rocks of Duiker Island are packed with Cape fur seals basking in the sun.
Just out of reach of the Atlantic swell, hundreds of the surprisingly large mammals jostle, or lounge in the warmth.
It is a majestic spectacle straight from a wildlife documentary – but all is not as it seems.
Surfers, swimmers, beach goers and pet dogs have all recently been attacked and bitten by the animals, which in the case of bulls average around 40 stone (250kg) in weight.
A local tourist business that offered guided ‘snorkelling with seals’ trips had to stop the excursions after visitors and staff were attacked.
And just last month, seals thought to come from the Duiker Island population twice attacked people at nearby Kommetjie beach, a popular surf spot.
Biologists have been trying to uncover the cause of this indiscriminate aggression. Early suspects included distemper and domoic acid, from poisonous algae.
ADVERTISEMENT
Then in July came a shock revelation from tests on four seals linked to attacks on people: three of them tested positive for rabies.
Piloting his inflatable boat around the rocks, Gregg Oelofse, the coastal manager for the City of Cape Town, is scanning the throngs for the telltale signs of infection.
“We are looking for unusual behaviour” he says, keeping his eyes on the seals. “They could swim a bit differently, with their heads out of the water like they are a mongoose almost.
“Or, if there’s one with a lot of space around it, where everyone is trying to stay away from it. Or, if it comes up and attacks the boat, tries to bite the engines, all that sort of thing.”
Unusual aggression has been on the rise in seals around Cape Town for the past 18 months, posing a public health and conservation conundrum about what to do.
ADVERTISEMENT
Complicating the picture and adding to concern about the seals’ health, large numbers of dead animals have been washing up along the coast.
Rabies had been an early suggestion for the solution to the puzzle, however it had seemed unlikely because the disease had never before been found in significant numbers in marine mammals. The only other recorded case in seals involved a single animal in Norway’s Svalbard islands in 1980.
Yet, from those first three rabies cases confirmed in the summer, the number has quickly risen.
By December there had been more than 40 confirmed cases found along the Cape coast, said Mr Oelofse. Rabies has also been found in tissue samples taken from the dead bodies of seals collected over the past two years.
After beginning with what looked like isolated cases, vets and scientists are starting to think the disease is already part of the population.
ADVERTISEMENT
“The vets are very much of the view that it’s here to stay and that it’s endemic,” says Mr Oelofse, “which is not great from our point of view.”
Firstly, the disease is horrific for seals, and he has seen rabid animals badly injure themselves and other seals as they succumb to the aggression and erratic behaviour which are common symptoms.
“I have seen some horrific facial injuries on seals that have got rabies, they bite the rocks and they rub their faces raw until it’s just their bones sticking out,” he says.
“It’s terrible. They snap their teeth on the rocks. When other seals get attacked by rabid seals, they rip their faces off. It’s some of the worst animal suffering I have seen.”
Secondly, there is the risk to humans from a terrifying and incurable disease.
Rabies virus is estimated to kill around 60,000 people worldwide each year, almost all from dog bites or scratches in Asia and Africa.
ADVERTISEMENT
While it can be stopped by vaccination or early treatment, once the full-blown disease develops, it is always fatal.
“Obviously we want to do everything we can to prevent the transfer of rabies to a person,” Mr Oelofse says. “That’s a big priority for us. So far we have been lucky, we hope to stay lucky.”
Anyone bitten must quickly be given a series of preventative injections and so far, none of the bites inflicted by seals have caused rabies in a person.
The discovery of aggressive rabid seals has caused shock in an area where the animals have long been viewed fondly and where large numbers of tourists and locals enjoy life on the beach and in the water.
South Africa’s National Council of Societies for the Prevention of Cruelty to Animals (NSPCA) advises beach goers to use caution and says the public “is strongly advised to avoid close contact with seals”.
Conservationists worry that fear of rabies could now lead members of the public to mistreat or harass seals.
Dr Tess Gridley, who has been studying seal health for several years with the Sea Search collective, said: “In South Africa you kind of have a feeling of which species you should be wary of and which species you are kind of okay around and this is drastically changing our perception of Cape fur seals.
“Its very sad that this is happening. In the most part there has always been a very good relationship between the public and seals.”
Only months since the first disclosure of rabies, there are still many questions about the outbreak.
The best guess is that the disease spread from local jackals or dogs which have been known to carry rabies in South Africa. Genetic sequencing has shown the virus in seals is related to that seen in wild animals in Southern Africa.
How long it might have been circulating undetected is unclear. The earliest diagnosis so far has been in a dead seal from August 2022, though with hindsight, 2021 video of aggressive seals also now appears to show rabies symptoms.
Studying what is going on is not easy, says Dr Gridley.
The seals range widely and live in loose family groups. Their interactions mainly take place unseen many miles from people, either far out in the ocean, or on remote coastline.
Testing is also difficult, because it needs brain tissue. Animals only test positive for rabies in the latter stages, when they are already showing symptoms and are close to death. During a long incubation period, the disease is hidden. The high cost of testing means the local authorities reserve it only for animals that are known to have already bitten people or dogs.
If rabies is now endemic in Cape fur seals, then South Africa must learn how to manage the disease.
With an estimated two million animals on the coast between southern Angola and South Africa’s Western Cape, vaccinating them all is not feasible, but targeted vaccination is underway.
One major goal is to stop it spreading to other seal species. Leopard seals and elephant seals seen visiting fur seal populations are being vaccinated to stop them taking the infection back.
Vaccination can also be targeted at seals that habitually hang out near humans. This includes specific animals that live in close proximity to tourists, harbour workers, and fishing people.
At the same time, by surveying populations like Duiker Island, conservationists hope to be able to quickly spot and put down infected animals.
Spotting them is not simple. While aggression is a rabies symptom, biting and boisterousness are also normal social behaviour for the seals. That also spreads the virus.
“As you can see, the way seals interact with each other is by biting and all those things, so it’s an easy way for the virus to move between, because it’s saliva and bites,” explains Mr Oelofse.
“Where I think we are lucky with the rabies is that when they develop symptoms, it’s not long until they die from the disease, which is why it’s not necessarily a virus that floods the population, it’s kind of a slow burn.”
He also looks out for dead seals, though those in themselves are not necessarily a sign of anything untoward.
“High mortality in a seal population is quite normal,” he explains. “It’s boom and bust and it’s quite hard to see when it’s changing. It’s food availability and weather and predation. It’s a brutal existence.”
Researchers now believe that the die-offs seen in recent years are related to algae, and not related to the rabies finding.
As Mr Oelofse patrols around the rock, his boat approaches a floating dead pup and the body is taken ashore for testing.
“It just is one way for us to keep some kind of handle on what’s going on if we can,” he says.
Protect yourself and your family by learning more about Global Health Security
EMEA Tribune is not involved in this news article, it is taken from our partners and or from the News Agencies. Copyright and Credit go to the News Agencies, email news@emeatribune.com Follow our WhatsApp verified Channel
