Dr Bryan Betty warns cryptosporidium bug is 'very hardy' amid surge in cases, diarrhoea can last four weeks

A general practitioner is warning the surge in cryptosporidium cases is "very concerning" as the bug is "very hardy", with diarrhoea potentially lasting up to four weeks.   

It comes after Health New Zealand revealed on Thursday morning there have been 262 cases of cryptosporidium (or 'crypto') since the start of the year through to March 8. This is three times the average of 81 cases for the same period over the last five years.   

It has prompted Health NZ to issue a public health warning but the agency stresses there is currently no suggestion of a major cluster or concentrated outbreak, or any link to contaminated drinking water, which caused last year's Queenstown outbreak.   

General Practice NZ chairman Dr Bryan Betty told AM on Thursday morning it's "very concerning" to see the rapid rise in cases this year compared to previous years.   

Symptoms for crypto include diarrhoea, vomiting and stomach cramps, with Health NZ warning it can be particularly dangerous for young children and older people.  

Dr Betty told AM even though the number of cases is currently high, he warns there could be more in the community.   

"It can be reasonably mild and people might say that they just have a bit of loose bowel motion or diarrhoea and don't contact their general health practitioner," he told AM co-host Lloyd Burr.   

"The potential is that there are more cases out there, but generally people when they do get diarrhoea, vomiting and stomach cramps do tend to interact with the health system in some way."   

Dr Betty said the way people catch crypto is through contaminated water such as drinking water, not washing their hands after going to the toilet and then preparing food and the water getting on the food.   

It can also be through people swimming at rivers and beaches that are contaminated with sewage.  

"This is why it is so, so important, especially over summer where the signs go up to say don't swim there's been a sewage leak or whatever into this area that you don't do that," he told AM.  

"What tends to happen, people swim, they ingest a little bit of water. The bug is in the water, it is very, very hardy, it really does survive for quite a number of weeks and that gets into the system and causes the problems."   

Dr Betty warns people who do have crypto can have diarrhoea for up to four weeks.   

"We say the incubation period, that is the time it takes for the symptoms to come on is usually about seven days, but you can have diarrhoea anything from about four days through to four weeks," he said.   

"So it can be quite prolonged sometimes and we don't necessarily treat it. There's no real treatment, antibiotics generally don't help. So it's just the body getting rid of the infection itself." 

He told AM the "big, big issue" is if you have an acute infection, you can have the bug in your system for two weeks.   

"If you go to a swimming pool or a public shared space with water like a paddling pool, a swimming pool, paddling pool for children, two weeks after the infection, you can actually spread the disease. So this is really, really important to understand," he said.   

Betty urges anyone with symptoms to call Healthline to receive advice.   

Watch the full interview above.