{"id":2177684,"date":"2024-09-24T12:00:02","date_gmt":"2024-09-24T11:00:02","guid":{"rendered":"https:\/\/focusingonwildlife.com\/news\/?p=2177684"},"modified":"2025-05-27T13:33:34","modified_gmt":"2025-05-27T12:33:34","slug":"why-are-cape-fur-seals-in-south-africa-infected-with-rabies","status":"publish","type":"post","link":"https:\/\/focusingonwildlife.com\/news\/why-are-cape-fur-seals-in-south-africa-infected-with-rabies\/","title":{"rendered":"Why are Cape fur seals in South Africa infected with rabies?"},"content":{"rendered":"

In May this year, a seal at a popular beach in Cape Town, South Africa, bit five surfers in a matter of minutes. The surfers laughed it off with characteristic nonchalance, but seal experts were concerned because this extremely unusual behaviour seemed part of what was becoming a pattern.<\/p>\n

Six days earlier, on the other side of the city, a seal had washed up with horrific facial injuries that could only have been caused by a seriously aggressive animal.<\/p>\n

Starting in late 2021, authorities noted with concern an uptick in seal aggression. While most seals continued to ignore people, a few seemingly \u201cderanged\u201d animals had started biting people or other animals with no provocation.<\/p>\n

\u201cAlthough the behaviour looked \u2018rabid\u2019, our best scientific knowledge was that seals don\u2019t get rabies,\u201d says Dr Tess Gridley, founding director of Sea Search, an NGO specialising in marine mammal research.<\/p>\n

After the May attacks, as public speculation spiked, a decision was made to send four seals (the two previously mentioned and two others) for rabies testing. \u201cWe were desperately hoping it wouldn\u2019t be rabies,\u201d says Gridley.<\/p>\n

The answer was shocking: three out of those four seals tested positive for rabies. The number has since risen to 17.<\/p>\n

\"Healthy<\/a>
Healthy seals gather on a beach in South Africa. In May, a seal at a popular Cape Town beach bit five surfers in a matter of minutes [Courtesy of Sea Search]<\/figcaption><\/figure>\n

What\u2019s the current state of the outbreak?<\/h2>\n

At the time of writing, 17 seals along a 650km (404-mile) stretch of coastline between Cape Town and Plettenberg Bay have tested positive for rabies. Some of these positive tests have come from animals euthanised for their aggressive behaviour since the first case was confirmed, while others stem from retrospective testing of 130 specimens biobanked (preserved) by Sea Search as part of an unrelated investigation over the past three years. The number of positive cases \u2013 from both retrospective and future testing \u2013 is sure to rise.<\/p>\n

While research is ongoing, the latest sequencing suggests that the seals have a wildlife strain of the virus.<\/p>\n

\u201cOur best guess is that the seals got it from black-backed jackals,\u201d says Dr Brett Gardner, a veterinarian with a special interest in disease epidemiology who is based at the University of Melbourne in Australia. Rabies is endemic among southern African jackals, which prey on seal pups in land-based colonies on the West Coast of South Africa and Namibia.<\/p>\n

At least one domestic dog in Cape Town appears to have contracted rabies from a seal bite. So far, none of the humans who have been bitten by rabid seals have developed rabies.<\/p>\n

\"Biobanked<\/a>
Biobanked (preserved) specimens collected from seals by Sea Search, an NGO specialising in marine mammal research, were gathered three years ago and tested retrospectively for rabies [Courtesy of Sea Search]<\/figcaption><\/figure>\n

Why are experts so concerned?<\/h2>\n

It is the first outbreak of rabies among marine mammals anywhere in the world. The only other known case of a seal catching rabies took place in the Norwegian island of Svalbard in 1980 and was seen as an isolated incident.<\/p>\n

\u201cWe simply don\u2019t know what course the disease will take,\u201d says Gardner. \u201cAnd we have loads of questions about things like transmission rate. Will this resemble what we are used to seeing in conventional terrestrial mammals, or will it be more like the unexpected mass mortalities historically seen in kudu infected with rabies?\u201d<\/p>\n

Two million Cape fur seals live along a 3,000km (1,864-mile) coastline stretching from southern Angola to Algoa Bay on the east coast of South Africa. The seals spend days or weeks at sea, but when on land they live in crowded colonies where their need to defend their personal space results in frequent fights and squabbles \u2013 which is not ideal, considering rabies is primarily transmitted through saliva.<\/p>\n

On a potentially positive note, seals have less saliva than land mammals \u2013 swallowing slimy fish while underwater doesn\u2019t require much lubrication.<\/p>\n

\u201cWe are encouraged by the fact that no humans have developed rabies yet,\u201d says Gardner, who is curious about why this may be. \u201cIs the saltwater reducing the viral loads or partially inactivating the virus? Are people\u2019s neoprene wetsuits cleaning seals\u2019 teeth before they draw blood?<\/p>\n

\u201cWe don\u2019t know any of these answers yet.\u201d<\/p>\n

\"A<\/a>
A seal is tested for rabies in May 2024 [Courtesy of Sea Search]<\/figcaption><\/figure>\n

Is it safe to go to the beach in South Africa?<\/h2>\n

Surfers, swimmers, fishers and other water users have been urged to continue enjoying the ocean, but to do so with caution and to always walk dogs on leashes.<\/p>\n

\u201cThere\u2019s no need to panic if you see a relaxed seal,\u201d says Gregg Oelofse, who heads up the coastal management team for the City of Cape Town. \u201cBut if an animal looks frenzied or aggressive, please get out of its way and alert fellow beachgoers and the authorities.\u201d<\/p>\n

Some more non-specific signs that an animal might have rabies are incoordination and other neurological signs, Gardner says.<\/p>\n

Lifeguards and shark spotters in the affected areas have been instructed to close beaches if in any doubt, and companies offering seal snorkelling tours have been left with no option but to cease operations.<\/p>\n

Rabies is a slow-moving disease of the nervous system \u2013 it can incubate for months or even years. Once it becomes symptomatic, however, it is almost always fatal, in all species.<\/p>\n

If a person is bitten, the wound should be washed with soap and water for 15 minutes. The next step is to visit a doctor for a shot of rabies immunoglobulin (which binds to the virus) and a course of rabies vaccines. With this course of action, contracting rabies is extremely unlikely.<\/p>\n

What\u2019s the most likely outcome of the outbreak?<\/h2>\n

While both Gardner and Gridley emphasise that there is no scientific precedent when it comes to rabies outbreaks among marine mammals, experience of the disease in terrestrial animals suggests three possible scenarios.<\/p>\n