Villagers in Bihar's East Champaran district on Friday claimed that eight people have died in the past 10 days of a disease that doctors have been unable to diagnose.
Residents of Akauna village near Motihari town, about 200 km from here, claimed that the men who died were part of a group of 18 labourers who had returned from Nagaland, where they worked in forests.
The labourers had been complaining of severe body ache, high fever and weakness since their return.
Jitendra Rai, a villager, said: "Eight of the 18 who returned from Kohima died one by one in the last 10 days."
Mobin Hashmi, the doctor who treated the men, said he had failed to diagnose the disease they were suffering from and failed to understand the cause of the deaths.
"It appears to be the result of some mysterious communicable disease," Hashmi said.
"The government should take it seriously because the disease may spread fast and is likely to claim more lives if preventive measures are not initiated soon. The government should send a team of doctors to treat the others who are suspected to be infected," he added.
Dharmdev Singh, the district civil surgeon, said he had no information about the deaths from the local administration.