Animal Survival International (ASI) has warned that the outbreak has the potential to become a widespread marine catastrophe. Programme Director of ASI, Debby Querido, stated that what is unfolding along the South African coastline is unprecedented.
Image: Henk Bogaard / Supplied / ASI
While the alarm has been raised about the dangers of the rabies outbreak in the Cape fur seal population, the Department of Forestry, Fisheries and the Environment (DFFE) said that they are managing the disease through surveillance and on a case-by-case basis.
Dr Lesley van Helden, state veterinarian in epidemiology at Western Cape Agriculture Department in a recent interview touched on the rabies outbreak in seals, and explained that it is the first outbreak in a marine mammal.
“We do have rabies in various kinds of mammals that live on land, but this is the first time it's moved into the sea. It has become endemic in the Cape fur seal population, so that means wherever Cape fur seals occur along the coast, there's the potential of the case of rabies being in one of them.”
Van Helden said endemic means that the seal population is maintaining the infection, “the seals are passing rabies to each other, so the chances of the outbreak ending naturally are very slim”.
“It is more likely that rabies is here to stay in the Cape fur seals.”
Animal Survival International (ASI) has also warned that the outbreak has the potential to become a widespread marine catastrophe.
Programme Director of ASI, Debby Querido, has stated that what is unfolding along the South African coastline is unprecedented.
“There is potential for this outbreak to develop into a large-scale cross-species pandemic. I’m worried we are underestimating the danger this poses to our marine ecosystems and the animals that call them home,” Querido said.
ASI said it is suspected that the seals were infected by black-backed jackals, which prey on seal pups, but that regardless of its origin, the virus could spread rapidly throughout local marine mammal populations squeezed into the few natural spaces left untouched by human expansion – especially if it can jump species.
In the final stages of infection, the rabies virus essentially ‘commands’ the animal to bite, transmitting the virus through saliva. Infected Cape fur seals have been observed attacking each other, as well as people and pets.
“It is unknown if the seals are attacking other marine mammals in the open ocean, but this cannot – and should not – be ruled out,” it said.
“Around two million Cape fur seals are living in coastal colonies stretching 3 000km from the tip of South Africa through Namibia and into Angola. If the infection keeps spreading, the consequences could be dire.”
Seal biting rope. In the final stages of infection, the rabies virus essentially ‘commands’ the animal to bite, transmitting the virus through saliva. Infected Cape fur seals have been observed attacking each other, as well as people and pets.
Image: Damien Coulsen / Supplied / ASI
ASI Campaigner and Researcher, Savannah Anderson, added: “While the outbreak is devastating for local seal populations, the fear is that the virus could once again jump species, possibly infecting other marine mammals such as orcas, dolphins, and even whales.
“The more species are infected, the wider the outbreak could reach. Orcas, for example, could carry the virus long distances and infect marine mammals off the shores of Australia, the Americas, and beyond.”
General manager for advocacy at conservation group CapeNature, Petro van Rhyn, added that while the impact of the outbreak could lead to a decline in the seal population, there are several factors such as food availability, predation by sharks, other diseases, plastic pollution (entanglement), etc., that impact on the seal population.
“It would be difficult to isolate a single factor that could cause a decline. The seal populations at seal colonies are being monitored by DFFE and seals dying along the coast from various causes are being monitored by stranding networks. At present there is no cause for alarm.”
Van Rhyn said that the government has set up a Cape Fur Seal Monitoring and Response Group where all stakeholders share monitoring, stranding, rabid seal sightings, etc., daily.
“Operational teams are updating monitoring and reaction protocols regularly and this integrated group is continually reflecting on information being generated by all platforms.”
DFFE spokesperson, Peter Mbelengwa, said that a solution would be to vaccinate over 1.5 million seals throughout their distribution range, but that is not practical.
“The department, together with relevant stakeholders, is managing the disease through surveillance and on a case-by-case basis when such a case presents itself at areas where the seals are likely to interact with humans (e.g. at beaches).
“To aid this process, a case definition was drafted, describing what a suspect rabid seal would look like. Although the case definition was originally drafted for Cape Town, it has since been adopted widely.
“A vaccination drive was initiated for Cape fur seals at locations of high human traffic (i.e. harbours). This is a trial study to investigate the efficacy of available rabies vaccines on Cape fur seals,” Mbelengwa said.
“Additionally, the trial was extended to include vagrant seals, in particular, the Southern elephant seal. This southern ocean species visits South Africa and mingles with Cape fur seals at their breeding colonies. Thus, the idea is to limit the transfer of the virus to the Southern Ocean population of elephant seals.”
He explained that a Standard Operating Procedure (SOP) for the surveillance of the Cape fur seal colonies in Cape Town and other areas (Plettenberg Bay, Gqeberha, Mossel Bay, and other coastal areas) has been drafted. The SOP covers euthanasia of suspect rabid seals which must be tested for rabies upon putting down.
“Lastly, the department and involved stakeholders have agreed that public awareness would be the best avenue to limit the impact on humans (through bites and attacks on pets, etc).”
Mbelengwa added that it is most likely that the virus has been in the population undetected for a while, but the department and relevant stakeholders will be monitoring the population for mass die-offs or any major disruptions to the normal behaviour of Cape fur seals, and ascertain if these would be rabies-related.
“It is during these episodes and based on the outcome of the investigations that the department will be better placed to address concerns and implement interventions (where practical and feasible) in collaboration with the Department of Agriculture, the competent authority for controlled diseases like rabies.”
Experts have cautioned the public to be wary of seals in areas where humans may interact with them, including when swimming, surfing, or paddling in the oceans of South Africa, Namibia, and southern Angola.
ASI said that anyone who may come into contact with seals should get a rabies vaccination and should keep their pets' rabies vaccines up to date, especially dogs that walk on beaches.
Mbelengwa added that a rule of thumb for the public should be to always stay clear of any seal they encounter.
“In instances where a suspect rabid seal is encountered, the public should consult any of the following depending on their local dynamics: the DFFE, municipality, state vet, private vet, environmental authorities (including agencies like SANParks, CapeNature), local NGOs, seal rescue centres (including aquariums) and other interested and permitted parties (seabird, turtle, snake sanctuaries).
“South Africa has a good network of professionals and volunteers; the message will get through to these highly dedicated individuals and organisations through any of the mentioned avenues.”
theolin.tembo@inl.co.za