CAPE TOWN, South Africa (AP) — Scientists in South Africa say they’ve recognized an outbreak of rabies in seals that’s believed to be the primary time the virus has unfold in sea mammals.
No less than 24 Cape fur seals that had been discovered useless or euthanized in varied areas on South Africa’s west and south coast had rabies, state veterinarian Dr. Lesley van Helden mentioned.
Rabies, which impacts mammals and will be handed to folks, is nearly at all times deadly as soon as signs seem. Rabies spreads through saliva, normally by way of bites but additionally generally when animals lick and groom one another.
The virus has lengthy been seen in wild animals corresponding to raccoons, coyotes, foxes, jackals and in home canines. But it surely had by no means been recorded spreading amongst marine mammals, van Helden and different consultants mentioned this week.
The one different identified case of rabies in a sea mammal was in a ringed seal in Norway’s Svalbard islands within the early Nineteen Eighties. That seal had possible been contaminated by a rabid arctic fox, researchers mentioned, and there was no proof of rabies spreading amongst seals there.
Authorities in South Africa first found rabies in Cape fur seals in June after a canine was bitten by a seal on a Cape City seashore. The canine turned contaminated with rabies, prompting rabies assessments on mind samples from 135 seal carcasses that researchers had already collected since 2021. Round 20 new samples additionally had been collected and extra positives have come again on subsequent assessments.
Scientists try to work out how rabies was handed to the seals, whether or not it’s spreading broadly amongst their giant colonies and what will be accomplished to include it.
“It’s all very, very new,” mentioned Greg Hofmeyr, a marine biologist who research seals in South Africa. “A whole lot of analysis is required … there are numerous unknowns right here.”
There are roughly 2 million seals migrating forwards and backwards between South Africa, Namibia and Angola alongside Africa’s south and west coast. The most certainly chance, van Helden mentioned, is that rabies was first handed onto seals by jackals in Namibia, the place the wolf-like animals hunt seal pups on the shoreline.
The genes of the rabies virus discovered within the seals matched the rabies in black-backed jackals in Namibia. It additionally confirmed rabies was being transmitted between seals, as a result of many of the virus sequences had been carefully associated, she mentioned.
“So, it’s principally established itself within the seal inhabitants and it’s being maintained by them biting one another,” van Helden mentioned.
The seals dwell in shut proximity to folks in locations in South Africa, particularly on seashores across the metropolis of Cape City. The town has issued warnings to locals, mentioned Gregg Oelofse, Cape City’s head of coastal and environmental administration.
Authorities had been mystified for the previous three years by stories of excessively aggressive seals and a rise in seal assaults on folks, a few of whom had been bitten. No human circumstances of rabies have been recorded in consequence.
Oelofse mentioned that metropolis authorities had began vaccinating the small numbers of seals at two well-liked Cape City harbors, the place they’re thought-about an attraction.
One of many optimistic rabies assessments was on a seal carcass collected in August 2022, that means rabies had been within the seal inhabitants for at the least two years, Oelofse mentioned.
“It’s been right here for some time longer than we’ve identified about it,” he mentioned.
Consultants mentioned there have been nonetheless many unknowns.
It’s arduous to foretell long-term transmission dynamics, U.S. Facilities for Illness Management and Prevention spokesman Dave Daigle mentioned. He famous earlier situations of rabies viruses winding up in new hosts after which dying out. In 2021 within the U.S., for instance, grey foxes had been spreading the raccoon rabies virus variant for 2 years, after which transmission stopped.
The U.S. public well being company is watching the scenario in South Africa, however has but to see “clear proof that that is going to be a long-term difficulty,” Daigle mentioned.
One other unknown is that if the vaccine will probably be efficient in seals. It’s by no means been examined, however consultants suppose it ought to work.
There’s additionally a logistical query, van Helden mentioned: How do you vaccinate a major variety of seals that dwell largely within the ocean and migrate forwards and backwards alongside a shoreline that’s greater than 3,500 kilometers (2,170 miles) lengthy. Land animals will be vaccinated by dropping bait that releases oral vaccines when eaten, however seals usually will solely eat dwell fish, she famous.
South African officers have been collaborating with worldwide consultants.
Seal researcher Hofmeyr mentioned that another seal species come into contact with Cape fur seals after which journey to different components of the world and that was a priority for additional unfold.
“The possibilities of that occuring are very low, however the implications of that if it does occur are crucial,” he mentioned.
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AP Africa information:
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