People in Papua New Guinea's capital, Port Moresby, are being told to stay away from two lakes after polio was detected in them.
The World Health Organisation is warning people to stay away from the ponds in Morata and Waigani, which is an outlet for the city's sewage discharge.
The WHO's Luo Dapeng said the detection is not entirely surprising given that a case of vaccine-derived polio was recently detected in Port Moresby.
He said that for every case, there will be at least 200 infections that may show no symptoms.
With a mass polio vaccination underway in the capital, people will be shedding the polio virus from their bodies.
However, the country's polio outbreak derived from cross contamination with faeces containing the weakened strand of polio used in vaccines, which is why people should stay away from the lakes.
