Stomach bug closes swimming pool
Mid Canterbury Selwyn
A Canterbury swimming pool has been closed after an outbreak of a diarrhoea-causing bug.
Nine people in Selwyn have been confirmed to have cryptosporidium, a bug which causes severe stomach cramps and diarrhoea, in the last month.
While sources are still determining the exact cause of the outbreak, the Selwyn Aquatic Centre has been closed as a pre-cautionary measure.
Canterbury Medical Officer of Health Dr Alistair Humphrey said they were interviewing all people with confirmed cryptosporidiosis in an attempt to identify a common source.
"While we are still looking into the source of the outbreak, our preliminary investigations suggest that it may have been spread by someone with cryptosporidium swimming at the Selwyn Aquatic Centre," Humphrey said.
Six of the nine confirmed cases are from people who had gone swimming at the Selwyn Aquatic Centre, and another case had two siblings who had been swimming at the centre.
The Selwyn District Council decided to close the aquatic centre until more was known on the outbreak.
"We don't yet know for sure how the disease is spreading; proactively closing the pool is the responsible thing to do," Humphrey said said.
"It is important that the pool does not become a vector for further spread."
A spokeswoman said the first case was notified on August 14 and the latest just yesterday, but the outbreak may have occurred earlier.
Symptoms usually appeared between two and 14 days after exposure, but the average was 7 days.
"There is obviously a lag between getting symptoms, then going to doctor, then doctor notifying Community and Public Health," she said.
Selwyn Aquatic Centre Manager Kathy Moore said cryptosporidium was known to be a difficult organism to kill and treat when it was brought into swimming pools by a member of the public.
"Although the aquatic centre operates to best quality water treatment guidelines, cryptosporidium is resistant to chlorination and can survive standard pool water quality treatment methods," Moore said.
"A number of other pools in New Zealand have experienced problems with this organism despite having good water filtration and treatment systems in place."
The water in the pools would be removed, discarded and replaced with fresh water. Pool systems would also be "repeatedly flushed" to clear out traces of the bug.
Moore said the pool will remain closed until test results had been returned confirming the water is safe.
This was expected to take around two weeks.
Cryptosporidium is an organism that can cause gastrointestinal illness with diarrhea. It can be contracted from contact with farm animals, by drinking untreated water, from contact with faeces, in food or spread in swimming pools.
It is more commonly reported in rural areas and reported cases peak in the springtime.
Common symptoms of Cryptosporidium include diarrhoea (often watery), stomach cramps and abdominal pain, lack of appetite, and weight loss. Nationally, 877 cryptosporidium cases were reported in New Zealand in 2012.
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