Health officials in Bangladesh have described the condition of hundreds of factory workers in the country, who have fallen sick in recent weeks, as a type of 'mass hysteria'.
Garment workers at several factories fell sick with stomach pains and vomiting, leading officials to initially suspect contaminated drinking water at their workplaces as the cause.
But doctors and microbiologists investigating the illness said they found nothing wrong with the water supplied at one of the factories where up to 600 workers fell ill earlier this month.
Instead a team from the country's Institute of Epidemiology, Disease Control and Research (IEDCR) suspect a condition known as "mass hysteria" which struck the country about eight years ago, and forced dozens of schools and factories to close.
"Water at Starlight Sweaters contained normal contaminants," the director of IEDCR, Mahmudur Rahman, told AFP, referring to the factory where some 600 workers fell ill.
"We suspect it (to be) a mass psychogenic illness or mass hysteria that affects people from a same group. This happens to mentally and physically vulnerable people," he added.
The condition appears highly contagious -- as soon as one or two workers fall sick, others are immediately struck with similar symptoms, he said, adding that extremely hot weather contributes to their vulnerability.
"This type of illness can be triggered by big events or tragedies. This is obvious because the disaster of Rana Plaza and subsequent highlighting of poor conditions in our factories have panicked garment workers," Rahman said.
At least 1,129 people were killed in one of the worst industrial tragedies when Rana Plaza, a nine-storey complex housing five garment factories, collapsed in April outside Dhaka.
The disaster coupled with a series of deadly fires renewed concerns over appalling safety problems in Bangladesh's $20 billion garment industry in which 4,500 factories employ more than three million workers, 80 percent of them women.
Rahman feared that more workers could fall sick to the "panic attack" linked to mass psychogenic illness, "unless there is counselling for them and assurances that safety standards would be improved".
About 2,000 pupils and workers have been affected by the illness in dozens of schools and factories since it was first reported in August 2005, according to statistics from the IEDCR.
A factory was closed in the southeastern port city of Chittagong in June 2010 after 700 workers complained of acute stomach pain, fainting and vomiting, which doctors blamed on the illness.
Authorities shut down at least four schools one month later in the southwest district of Jessore after around 100 students fell sick.