Cryptosporidium outbreak: What we know about cases on the rise across NZ

Wednesday, 29 May 2024

An outbreak of cryptosporidium, a gut infection causing parasite, has hit hundreds of people across Aotearoa.

From the beginning of 2024 to May 17, 676 cases of crpyto were notified to public health services nationwide, with most cases reported in the Auckland, Waikato and Canterbury regions.

Last week, Rolleston’s Selwyn Aquatic Centre was linked to 18 crypto cases - 14 directly and four from person-to-person transmissions.

Selwyn District Council says the pool is now safe to swim in, though Heath NZ Te Whatu Ora warns anyone who has been symptomatic should avoid swimming for another 14 days after symptoms have stopped.

In late 2023, a crypto outbreak in Queenstown believed to be caused by human faeces reached 72 cases in November.

What is it, and where does it come from?

Cryptosporidium is a parasite which affects humans after being swallowed - this occurs most often with people consuming contaminated drinking water, or by touching mouths with infected hands.

The parasites can also be passed through human or animal faeces, which can then contaminate soil, food and water, surfaces and toys.

These parasites live for long periods, especially in water sources, and there is no way of telling by taste, sight or smell if soil, food, water or a surface has crypto.

Dr Susan Jack, National Clinical Director for Protection at Health New Zealand Te Whatu Ora, says some of the localised outbreaks have been connected with swimming pools.

“In approximately half the cases where information is available, those who became unwell with symptoms had been involved in swimming-related activities – with the majority of cases overall recorded in urban areas,” Dr Jack says.

A Public Health Communication Centre report released on Monday found that weather events causing heavy rainfall and flooding may also play a role in crypto outbreaks.

The symptoms

Crypto is respiratory and gastrointestinal illness, with symptoms including:

• Diarrhoea

• Stomach cramps or pains

• Nausea and vomiting

• Bloating

• Slight fever

• Fatigue

• Flatulence

• Headache

Symptoms appear between the first and twelfth day of infection, though in most cases symptoms become noticeable after a week.

Those infected may be ill for two weeks or more and some, such as the very old or very young, may experience longer periods of infection that could be life-threatening.

Crypto parasites may still be present in faeces after symptoms have disappeared, meaning you can still infect others.

How it’s treated

People infected with crypto should see a doctor, who will likely ask to provide a stool sample.

There is currently no treatment for crypto, but some medicines may ease recovery and provide symptomatic relief. Drinking plenty of water is recommended.

To prevent the spread of crypto, proper hand washing before preparing food, eating, drinking and after using the toilet or changing a nappy is essential.

“This means washing your hands with soap and water for at least 20 seconds and drying them thoroughly with a clean towel every time you go to the bathroom and before preparing food,” Dr Jack says.

“Good hand hygiene is also important after contact with animals, after gardening, when caring for someone with diarrhoea, and when caring for a baby or changing nappies.”

If tramping or camping, take care when drinking untreated water, or avoid drinking water altogether from lakes, rivers, streams or any other source from which you can’t verify the quality of the water.

Avoid going to work, school or daycare until you have been free of diarrhoea symptoms for 48 hours.

Swimming areas can also be a cause of illness if they are contaminated by sewage or animal faeces. To avoid getting crypto, people should check water quality monitoring warnings before jumping in the water.

Land Air Water Aotearoa (LAWA) has information for the whole country, while those in the Northern Region can visit www.safeswim.org.nz to check local water quality.

Anyone experiencing severe illness, difficulty maintaining adequate fluid intake or long-lasting diarrhoea should seek health advice. If you have these symptoms contact your usual healthcare or hauora provider or call Healthline for free anytime on 0800 611 116.