Diphtheria had been all but eradicated in Bangladesh until last year, when more than 650,000 Rohingya poured across the border fleeing a bloody military crackdown in neighboring Myanmar.
Packed into an area meant for a much smaller number of refugees and with little sanitation or healthcare, the new arrivals provided fertile ground for the highly contagious respiratory disease to take hold.
It quickly spread through the camps, with the World Health Organization reporting more than 3,600 cases.
The outbreak has already claimed the lives of at least 30 refugees, mostly children, while a handful of Bangladeshis living near the camps have also contracted the disease.
Carla Pla, head nurse at the specialist diphtheria unit run by medical charity MSF (Doctors Without Borders), said children were arriving with “severe” symptoms.
“This is a very challenging situation, because every day there are coming more children, and the challenge to get the vaccine is also something that is very difficult,” she told AFP at the unit.
Nearly 600 refugees have been referred there since it opened in December, putting enormous pressure on doctors also struggle to treat rampant malnutrition, water-borne disease and other diseases in the camps.
Bangladesh authorities were prepared for other diseases and moved quickly to inoculate the new arrivals against cholera and measles to prevent a health disaster. But the emergence of diphtheria, which causes difficulty breathing and can lead to heart failure, paralysis and death if left untreated, caught aid workers off guard.
“We were taken aback when tests confirmed diphtheria in the camps. It was a long-lost disease in our country,” said Abdus Salam, the chief medical officer for Cox’s Bazar district, where the camps are located.
“Immediately, we acquired vaccines from abroad for an emergency response.”
In December, they launched a huge vaccination push. Nearly 320,000 children under 15 have now been inoculated and another 160,000 children are expected to receive the vaccine this month.
High rates of vaccination mean diphtheria has become increasingly rare in much of the world, although Yemen is currently suffering an outbreak.
But the Rohingya come from impoverished Rakhine state, where state-imposed restrictions have ensured abysmal living standards for the persecuted Muslim community, and many children are not vaccinated.