Polyneuritis has struck some 30 people in the northern province Hoa Binh.
The syndrome can be caused by a variety of things, but it ultimately leads to the widespread inflammation of nerves causing pain and tingling in the limbs.
It can be fatal.
The recent outbreak comes after three years without a single case in the province. Previously, Hoa Binh had suffered polyneuritis cases and fatalities on an annual basis
The recent outbreak has affected whole families. One of the first victims in Binh Chan Commune's Dai 1 Hamlet this year was Bui Van Nhi, who suffered pains in the tips of his fingers and toes, and fatigue two weeks ago.
His mother, wife and three children began to exhibit the same symptoms.
Vu Van Tien, director of the health center of Lac Son District, which manages Binh Chau Commune, said the disease is typically confined to the Canh 1 and Canh 2 hamlets. Lately it has spread to other localities.
Since April, several families in Binh Chan Commune have contracted polyneuritis.
The disease can have a variety of causes, the simplest of which is a lack of B vitamins. Authorities are not sure why this outbreak is occurring in the province - though they continue to treat victims with B1 supplements.
Bui Van Hong, vice director of the health center of Lac Son District, which manages Binh Chan Commune, said the vitamins have only provided such temporary symptom relief to the afflicfed.
He didn't say if patients develop the symptoms again.
Some have suggested the vitamin deficiencies may be the results of mercury poisoning. Toxic polyneuritis was recorded in Bombay nearly 50 years ago due to ortho-cresyl-phosphate poisoning.
To date, health experts, including those from the Ministry of Health and scientists in Japan, Denmark, and Germany, have yet to pinpoint the root of the recuring disease in Hoa Binh and Thanh Hoa, according to Tien.
He said the disease was first recorded in 1970 and has continued to break out ever since in the central regions ever since. In 2000, over 4,000 people were affected in Hoa Binh Province.
Although health agencies managed to control the disease then, it still recurs every year in Hoa Binh Province, affecting tens of people and killing several.
No deaths have yet been reported this year, though.