A representative of Quang Tri’s General Hospital said the number of patients with the disease caused by the bacterium Burkholderia Pseudomallei, which infects both humans and animals, has increased sharply since the first floods in mid-October.

The four confirmed deaths included a 51-year-old man from Hai Phong City in northern Vietnam. He was one of the crew members of cargo vessel Vietship 01 that got stuck in rough seas around 400 m off the coast of Quang Tri Province last month. After being rescued by military forces after days stranded at sea, he was taken to hospital for treatment and diagnosed with melioidosis.

The three others, 47, 62, and 75, hailed from Huong Hoa, Cam Lo, and Hai Lang districts of Quang Tri.

Quang Tri and other central provinces were hit by a series of storms and tropical depressions last month, which caused heavy rains, floods and landslides.

Le Van Lam, head of the hospital’s department of resuscitation and anti-poisoning, said each year the facility recorded more than 10 cases of Whitmore's disease, of which only one patient has died.

Whitmore patients do not have specific clinical manifestations; therefore, it is difficult to detect infected cases. Lam ascribed the majority of deaths to patients with severe background diseases and late detection.

On November 14, a Quang Binh Province official who had spent days in floodwaters managing relief efforts died of the disease while in hospital.

The nearby Thua Thien-Hue Province has also reported a spike in the number of Whitmore's disease patients linked to prolonged flooding.

Melioidosis patients typically suffer symptoms like fever, pneumonia and abscesses, along with inflammation of the brain and joints. The associated mortality rate is around 40 percent.

The disease was first diagnosed in Vietnam in 1925, though sufficient knowledge of the illness is still lacking.

Around 10,000 cases are reported worldwide each year, mostly during the rainy season, around half of which prove fatal. There is no vaccine.