More than 30 people including 10 children in Papua New Guinea have been hospitalised with suspected cholera.
The Post Courier newspaper reports they have been admitted to Modilon Hospital and Yagaun Health Centre and provincial authorities have gone into full response mode.
The admissions come after the province scaled down its cholera prevention status from high alert to stand-by mode about two weeks ago.
The Madang Provincial Health Adviser, Marcus Kachau, says the first of the admissions were made at the weekend.
Mr Kachau says so far only one death has been reported.
He says initial tests that had been carried out proved negative but the clinical presentations strongly suggest signs of cholera.