The microscopic amoeba, otherwise known as Naegleri Fowleri, enters the body through the nose and develops rapidly, according to Dr Nguyen Hoan Phu, deputy head of the hospital’s infectious-disease ward.
It migrates through the olfactory nerve to the brain, causing headaches, a high fever and possible loss of behaviour control.
The man, who had moved to HCM City to earn a living as a peanut seller, began to get a headache and fever after he returned to HCM City following a break in his hometown.
On July 29 he was brought to Gia Dinh People’s Hospital, which identified the presence of the amoeba.
One day later, as his condition worsened, the hospital transferred him to the city’s Tropical Hospital. His fever was 40 degrees Celsius until the day he died on July 31.
Phu said he was in a coma for two days before his death.
The man, who was the first patient in HCM City to contract such an infection, had been fishing for oysters and snails underwater at a lake near his house.
Most patients infected with the amoeba die, according to Phu.
In the US, 121 patients have contracted an infection from the amoeba since 1937. Ninety-nine percent of them die and there is only one known survivor.
However, Phu said that if patients are treated very early, the possibility of recovery is high.
Anyone with similar symptoms should go to a hospital immediately, he added.
Doctors in Vietnam have little experience in diagnosis and treatment, he said, adding that patients could be incorrectly diagnosed with encephalitis caused by viruses or bacteria.