Confidence there's a low risk of Queenstown's cryptosporidium outbreak spreading further afield

Health authorities have confirmed person-to-person transmission of the gastro illness, with cases of infection now reaching 60.

The source is still not known.

Te Whatu Ora southern Medical Officer of Health Doctor Susan Jack says they've had visitors that have developed the illness since returning home from Queenstown.

But she says as long as confirmed cases practice good hygiene, the parasite illness shouldn't go any further - and there's no great risk it will spread wider into South Island communities.