People with diarrhoea have been urged to stay out of swimming pools for at least two weeks after they recover to avoid spreading gastro.
NSW Health has warned that cases of cryptosporidiosis are expected to rise this summer as people flock to public pools to enjoy the sun and seek relief from the heat.
Cryptosporidiosis is caused by the cryptosporidium parasite that is easily spread in swimming pools, splash parks, interactive fountains, spas and jacuzzis and from person to person.
It is spread less commonly via drinking contaminated water or by handling infected animals.
With 1200 cases already confirmed this year, just two shy of last year's total, the number of cases in 2017 is likely to outstrip the figures from 2016, Jeremy McAnulty, director of health protection at NSW Health, said.
February 2017 was the worst month for the illness since January 2010, with 314 cases detected, Dr McAnulty said.
Since November 1, 56 cases have been detected in NSW, but this is likely to be an underestimate, he said.
Dr McAnulty said people of all ages, particularly parents and carers of young children, should take steps to prevent the spread of the infection.
"We usually see cases increase over summer, and there have been plenty of outbreaks caused by contaminated swimming pools.
Many people with diarrhoea won't get tested for cryptosporidiosis, which requires a stool test at the doctor.
"If an infected person gets into a pool, and another swimmer swallows even a small amount of pool water, they can get infected and will start experiencing diarrhoea a few days later," Dr McAnulty said.
"You can also get the infection from drinking water contaminated by animals or by handling infected animals - although this is less common."
Symptoms can include excessive diarrhoea, stomach cramps, nausea, vomiting and fever.
There is no specific treatment and symptoms may last a few weeks, Dr McAnulty said.
The Public Health Act was recently amended to expand the maintenance requirements for swimming pools including splash parks and interactive fountains to help reduce the risk of outbreaks.
"These amendments will help to prevent outbreaks but anyone with symptoms should help protect other swimmers by staying out of pools and splash parks for at least two weeks until the diarrhoea has stopped," Dr McAnulty said.
More than 1000 people in NSW contracted the intestinal infection during a flurry of outbreaks in 1998.
NSW Health recommended the public take the following steps:
- Do not swim in a pool for at least two weeks after diarrhoea symptoms disappear
- Regularly take children on bathroom breaks
- Ensure children wear waterproof tight pants over swimmers if not toilet trained
- Change nappies in a bathroom and not on the pool deck
- Wash children thoroughly with soap and water before swimming
- Wash hands with soap and water after changing a child's nappy.