Northland woman contracts cholera strain, no public health risk

The patient said she was shocked to be diagnosed with cholera, as she believed the disease had virtually disappeared from developed countries.

Medical officer of health Dr Felicity Williamson said only two of more than 200 different strains of cholera are toxigenic and have the potential to cause an outbreak. While toxigenic cases are rare in New Zealand, non-toxigenic cases like this one do occur.

These cases do not pose any outbreak or epidemic risk potential, and are reported “from time to time” in the northern region - which includes Northland and Auckland, she said.

“These strains can cause vomiting and diarrhoea, wound infections and bloodstream infections, and are most often associated with exposure to stagnant water sources.”

The patient said she was questioned by Ministry of Health officials, who unsuccessfully tried to work out where she picked up the disease.

While the Mangawhai resident uses a rain water tank, the water is filtered and UV treated, and the five other adults and two toddlers staying at the house at the time did not get sick, she said.

The woman also does not eat raw shellfish nor raw home-killed meat, nor had she recently returned from overseas, with her last travel to Japan being six months ago.

“There were six adults living in the same house and nobody else got sick. I ate the same food as them and drank the same water too - the whole thing is totally bizarre,” she said.

The patient spent three days in hospital before she was discharged on January 13.

While she has mostly recovered from the dehydration, she still has a small piece of glass embedded in her hand from where she fell on her glass shower door.

After having to replace the shattered door, the woman said she was very lucky her house was not affected by the Mangawhai tornado two weeks later, which destroyed homes about 1km away from her.

The woman said she has not been told to do anything differently, with the source of the cholera remaining unclear.

“It’s a huge puzzle that nobody can put together.”

Williamson said no public health action is required because the strain of cholera was not found to be toxigenic.

Toxigenic or outbreak-strain cases of cholera are rare in New Zealand, occurring in people who have travelled overseas, usually to countries in Asia, she said.

There have been seven toxigenic cholera cases reported in New Zealand since 2006 and none in Northland for at least 25 years.

Even in toxigenic cases, person-to-person spread of cholera is rare, with people usually getting the disease from contaminated water or food.

In non-toxigenic cases like this, it is not always known what the source of their illness is, Williamson said.

“However, any clusters or linked cases are investigated by public health to ensure there is no risk to others or any risk of further spread. No risk of this sort has been identified recently.”

Williamson said public health has not been notified of any issues with water or sanitation in Northland.

Cholera facts

Source: The World Health Organisation

Denise Piper is a news reporter for the Northern Advocate, focusing on health and business. She has more than 20 years in journalism and is passionate about covering stories that make a difference.