The World Health Organisation warned today of a growing risk of a cholera outbreak in the makeshift refugee camps in Bangladesh where some 436,000 Rohingya Muslims have sought shelter from unrest in Myanmar.
A month after the exodus began, those dispersed in some 68 camps and settlements along the border do not have safe drinking water and hygiene facilities, according to the WHO.
The camps also face dire shortages of food and medicine in what has quickly become one of the world's largest refugee settlements.
"Risk of water borne diseases is high, especially there is very high risk of cholera and this is why everyone is concerned," the WHO said in a statement.
"Interventions are being scaled-up, however, the situation remains critical and challenging."
The latest influx has overwhelmed the camps around Cox's Bazar, which previously housed at least 300,000 people who had fled earlier violence in Myanmar's Rakhine state.
The WHO says mobile medical centres have been set up, while Bangladesh health authorities say they have treated some 4,500 Rohingya for diarrhoea in a month and vaccinated some 80,000 children for measles and polio.
"We are trying our best to face the challenges. But we are concerned," Enayet Hossain, deputy head of Bangladesh's health services, told AFP.
The Doctors Without Borders (MSF) group said last week the camps were on the brink of a public health disaster as filthy water and faeces flow through shanties.
It said a "massive scale-up of humanitarian aid" was needed, with adults on the cusp of dying from dehydration.
More than 436,000 refugees have crossed the border from Rakhine since August 25 when a military crackdown was launched following attacks by Rohingya militants, according to UN figures today.
The refugees have given shocking accounts of killings and mass rapes as Myanmar soldiers and Buddhist mobs drive them out of their villages.