NSW Health has advised those who have had diarrhoea not to swim for at least two weeks as the state records close to 500 cases of cryptosporidiosis.
Cryptosporidiosis is a diarrhoeal disease caused by a parasite known as cryptosporidium that infects the intestine.
The disease is usually caught when people swim in or swallow water contaminated with parasites.
Symptoms of cryptosporidiosis include acute diarrhoea, nausea, vomiting, fever, headache and loss of appetite.
There have been 498 cases of the disease recorded in NSW so far this year.
This is a nearly 500 per cent increase from the previous five-year average of 95 cases during the same time period.
Dr Jeremy McAnulty specifically warned parents about the disease as children under 10 have accounted for almost half of the cases in the state.
“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.”
Swimmers urged to avoid the water during heavy rainfall
Those who have had diarrhoea should avoid swimming and sharing towels for at least two weeks after symptoms resolve.
Food should also not be handled until 48 hours after symptoms clear up.
Children with diarrhoea should be kept home from school, childcare or playgroup for at least 24 hours.
NSW Health has recommended against swimming in the ocean during and one day after heavy rainfall to avoid catching the parasitic disease.
Swimmers should also avoid estuaries, creeks, rivers and dams during and at least three days after a downpour.
Untreated water from the ocean and in inland waterways should not be consumed.
Queensland has also seen a spike in cryptosporidiosis cases, with 823 infections recorded so far in 2024.
The state had 736 cases in January alone, which is a jump from 56 cases in January 2023.
Victoria has also experienced a recent surge in cryptosporidiosis, with a health alert issued in December.