The government of Vietnam intends to ask for international help to find out what is causing a skin infection that has already killed 19 people.
More than 170 people in the country's central province of Quang Ngai have reported symptoms of the mysterious illness, the BBC reported on Sunday.
The disease begins with a rash on the hands and feet and can progress to liver problems and multiple organ failure. Vietnamese health ministry tests have failed to identify the cause.
"This disease is challenging as we have not identified the root causes. If it is just an external skin disease why is it causing deaths and failures inside internal organs?" the BBC quoted Deputy Health Minister Thanh Long as saying.
The mystery disease was first reported between April and December 2011 and then subsided but broke out again last month.
The government of Vietnam has said it will ask the World Health Organization and the US Centers for Disease Control and Prevention to join its investigation.