Western Australian sea lions infected with high rate of Giardia

While outbreaks of cryptosporidiosis and giardia continue to close aquatic facilities across Australia, new research shows that a high proportion of Western Australia's sea lion population is infected with the parasite Giardia duodenalis.

Macquarie University’s Tiffany Delport used genomic sequencing to test the faecal samples of wild and captive Australian sea lions (Neophoca cinerea), searching for the tell-tale DNA of parasites Giardia and Cryptosporidium.

Reporting on her findings earlier this month, Delport found the rate of Giardia infection was highest in captive sea lions, closely followed by Australian sea lion colonies situated within 25 kilometres of human coastal settlements.

In Western Australia, Beagle and North Fisherman Islands are home to two wild sea lion colonies, 17.7 kilometres and 21.6 kilometres from human settlement respectively.

Delport says of the 30 faecal samples collected from these islands, 12 were positive for Giardia - an infection rate of about 40%.

Transmitted through the ingestion of contaminated food and water sources, Giardia can spread from human to mammal, and from land mammal to marine mammal.

Explaining her findings, Delport states "taking steps to minimise environmental pollution with human and domestic animal faecal material infected with cysts may reduce the spread of giardia to mammalian wildlife populations

“It is also important to consider that Giardia cysts are environmentally robust, capable of surviving extended periods of time outside of a host.”

In humans and domestic animals, Giardia can cause diarrhoea and loss of appetite, but adds “however, very little is known about the effects that Giardia has on many wildlife hosts, including marine mammals.

“As Giardia is observed in many marine mammal species, including endangered animals such as the Australian sea lion, it is important that future investigations monitor the impact of infection on host health and identify potential pathways from humans and terrestrial animals to wildlife populations.”

Delport did not find evidence of Cryptosporidium cysts in wild or captive sea lion populations.

Meanwhile, outbreaks of cryptosporidiosis and giardia continue to affect aquatic facilities across Australia - although such closures are seldom reported.

Most recently, having been advised of reported cases of cryptosporidiosis (pictured below) in Port Hedland by the Western Australian Department of Health, the Town of Port Hedland has closed its Gratwick Aquatic Centre.

Having been advised that members of the public with symptoms had recently visited the Centre, the pool was closed on Friday 28th November for overnight super-chlorination.

Dr Heather Lyttle, Public Health Physician for the Pilbara advised that Cryptosporidiosis "is a parasitic disease that is transmitted by person to person in households - the most common, contaminated water, swimming in contaminated water, or by contact with farm animals."

Dr Lyttle those infected with cryptosporidiosis should not swim in public swimming pools or attend playgrounds, splashpads, child care centres or schools.

Information on Cryptosporidiosis is available on the WAHealth website at www.healthywa.wa.gov.au/Healthy-WA/Articles/A_E/Cryptosporidiosis

Sea Lion image courtesy of Perth Zoo.

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