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.

NSW Health has urged people with diarrhoea to stay out of public swimming pools for two weeks to guard against contamination.

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.