Cryptosporidiosis outbreak in New Zealand, cases linked to public pools

A cryptosporidiosis outbreak in New Zealand, primarily impacting the Hutt Valley, has seen infections nearly double in the last two weeks. Thirty-seven of the 59 total cases reported since January 1 are linked to pool use, prompting warnings from health officials and preventative measures at public pools. The rise in cases significantly exceeds the typical annual count for the Wellington region.

Health New Zealand reported 59 cryptosporidiosis cases since the beginning of 2023 with 33 of them between January 1 and March 20. An additional 26 cases were reported in the 16 days between March 20 and April 5. The majority of cases are concentrated in the Hutt Valley area.

Jill McKenzie, a spokesperson for Health New Zealand, stated that 37 of the cases involved individuals who used a pool or had contact with an ill household member who used a pool. Early childhood centers in the region have received warnings due to the potential for rapid spread of the infection among young children.


Cryptosporidiosis causes vomiting and diarrhoea with infected individuals remaining contagious for up to two weeks. Councils in the region have implemented precautions at public pools. These include intensive treatments using chlorine and UV light.

Wellington City Council confirmed cases linked to its pools in March but Porirua City Council reported no cases linked to its public pools.

Dr. Craig Thornley, a medical health officer with the National Public Health Service, previously indicated that Wellington typically sees fewer than 20 cases annually. Underreporting is possible, suggesting actual case numbers could be higher.