Avoid swimming pools if you’re part of Australia’s surge in diarrhoea cases, say authorities

Health authorities are urging people with diarrhoea to avoid swimming pools as cryptosporidiosis infections surge across New South Wales and Queensland.

The cryptosporidium parasite, which causes acute diarrhoea and can survive in chlorinated water for many days, has been responsible for 498 cases of diarrhoea in NSW this year – a five-fold increase on the five-year average of 95 for the same period.

In Queensland, 736 cases were reported in January alone, representing a 13-fold increase on January 2023 cases. Of those, 39% were in children aged nine or under.

The parasite affects the intestine, causing diarrhoea as well as nausea, vomiting, headache, fever and loss of appetite.

In an attempt to halt the outbreak, NSW Health is advising those with diarrhoea to avoid swimming for at least two weeks after symptoms resolve.

The Health Protection NSW executive director, Dr. Jeremy McAnulty, said the infection was commonly acquired by swimming in and swallowing water contaminated with cryptosporidium parasites.

“The parasite survives for many days, even in chlorinated pools, and in the past very large outbreaks have been caused by people who had recently been infected going swimming,” he said.

“Almost half of the cases reported this year had been swimming during their exposure period, and with such a high proportion of young children affected and with many schools about to hold swimming carnivals, we’re urging parents to stay alert for symptoms,” he said.

The Queensland chief health officer, Dr. John Gerrard, said transmission “can occur in various settings, including swimming pools, water parks, and other recreational water facilities, where water may be contaminated with faecal matter”.

Swimming in estuaries and inland waterways during and for three days – one day for ocean beaches – after heavy rain is also advised against.

The University of New South Wales associate professor and infectious diseases scientist, Holly Seale, said “people don’t appreciate how easily” infections such as cryptosporidiosis can be transmitted across communities.

“I’m a parent of young kids, and if you have very young kids all together in a close environment, things can spread quickly,” she said.

“And once a child goes down it’s often the parents who follow next.”