An Australian sea lion has been reported with tuberculosis in SouthAustralia

Researchers from the University of Sydney have reported the first case oftuberculosis in an endangered, free-ranging juvenile Australian sea lion inSouth Australia. The type of disease is not the typical presentation oftuberculosis, as this was not found in the animal’s lungs, but in its abdomen.

“This finding is significant because tuberculosis is a zoonotic disease, whichmeans it is transferable to humans, so there are public health risks toconsider,” said Dr Rachael Gray, from the Sydney School of Veterinary Science.

“There is risk of transmission for researchers handling the animals, as wellas anyone involved in animal rescue or washed-up carcass disposal, or thoseworking at rehabilitation centres and involved in the disease diagnosticprocess,” she said.

The discovery has been published in the Journal of Wildlife Diseases.

Finding the young male

The discovery was made after a three-year-old juvenile male Australian sealion died in 2017 shortly after hauling itself onto Kingscote beach, KangarooIsland, South Australia. During an autopsy, the animal was determined to havesmall intestinal perforation and partial obstruction due to a strangulatingfibrous mass.

Dr Gray said: “This unusual finding means we need to maintain constantvigilance around zoonotic disease risk for any person in close contact withfree-ranging pinnipeds [seals, sea lions and walruses] of juvenile age orolder, independent of presenting signs.”

Breeding colonies

Dr Gray, who conducted the study with Mr Scott Lindsay, a veterinarypathologist at the University of Adelaide and a PhD candidate at theUniversity of Sydney, said the location where the diseased sea lion was foundwas close to the breeding colony where the animal was born.

Mr Lindsay said: “A review of tuberculosis in Australian sea lions and otherpinniped species suggests the disease is likely endemic in the population andis now confirmed in a geographical region contributing to the majority of pupbirths in this endangered species.

“Increased serological surveillance of the population is recommended to assessthe species’ risk from this and other endemic diseases,” he said.

Australian pinnipeds

Dr Rachael Gray and her team of scientists have been conducting world-classresearch in South Australia in order to save the endangered sea lion.

The Australian sea lion is the only pinniped species endemic to Australianwaters, ranging from the Houtman Abrolhos islands off the west coast ofWestern Australia to the Pages Islands in South Australia. The species isendangered, with a decreasing population trend (International Union forConservation of Nature Red List) from a low baseline attributed to 19thcentury commercial sealing.

The small population size increases the species’ risk of catastrophic diseaseimpact, as seen in the New Zealand sea lion where Klebsiella pneumoniae-associated neonatal septicaemia and meningitis contributed to 58 percent ofpup deaths between 2006 and 2010.

Hookworm infection provides an existing disease pressure for the Australiansea lion. Further, recovery from a significant disease impact would be limitedby the species’ low reproductive rate. The majority (86 percent) of pup birthsoccur in South Australia where there is dependence on just eight largebreeding colonies, including Seal Bay, Kangaroo Island.

Image: A healthy sea lion pup on Kangaroo Island, South Australia. Photo:Louise Cooper/University of Sydney

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