Spokesperson Jill McKenzie said the majority of cases were from the Hutt Valley, and 37 of them were people who used a pool, or had contact with an ill household member who used a pool. Photo: RNZ / Marika Khabazi
Cases in a cryptosporidiosis outbreak have risen sharply, with reported infections nearly doubling in the past two weeks.
Health New Zealand said 59 cases had been reported since the start of the year - 33 in the nearly three months between 1 January and 20 March, and a further 26 cases in the following 16 days to 5 April.
Spokesperson Jill McKenzie said the majority of cases were from the Hutt Valley, and 37 of them were people who used a pool, or had contact with an ill household member who used a pool.
The health agency also issued a warning to early childhood centres across the region, as the virus could spread easily among younger children.
The bug causes vomiting and diarrhoea, and people can remain infectious for up to two weeks.
A graph showing a rise in cryptosporidiosis cases in 2025. Photo: Health NZ / supplied
Councils around the region have been taking precautions at public pools, including intensive treatments with chlorine and UV light.
Wellington City Council confirmed there had been a couple of cases linked to its pools in March.
Porirua City Council said no cases had been linked to its public pools.
In the Hutt, Huia Pool's Hydro Pool was closed on Tuesday for draining and cleaning as a precaution in the wake of an outbreak.
The council said the decision came after Public Health advised someone had attended swimming lessons on 5 April while they were symptomatic.
That person contracted the crypto bug from a different source - not a council pool.
Swim classes at the Hydro Pool were cancelled on Tuesday, potentially through to Saturday.
The council said it was investigating whether participants in the swim classes could be accommodated at other pools.
Three historic cases had been linked to Te Ngaengae Pool, but the pool had since been treated and drained.
National Public Health Service medical health officer Dr Craig Thornley previously told RNZ typically Wellington would see less than 20 cases in a year.
Not all cases would be reported, so true case numbers could be a lot higher.
One woman described the "severe pain" her daughter was in after contracting the illness at the Wellington Regional Aquatic Centre in Kilbirnie.
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