Public health officials in Vietnam are investigating an outbreak of foodborne botulism that has killed one person.

The Vietnam Food Administration (VFA) said three incidents of food poisoning had occurred recently in Quang Nam province.

An outbreak in Phuoc Duc caused four cases and one death. The source was a type of fish contaminated with Clostridium Botulinum type E.

Food poisoning in Phuoc Kim also infected four people and an investigation in Phuoc Chanh is ongoing with officials waiting for results from testing of food and patient samples.

Earlier this week, the Quang Nam Department of Health organized training for medical professionals with instructions on early detection and how to treat botulinum poisoning, which is a rare but life-threatening condition, caused by toxins produced by Clostridium botulinum bacteria.

In foodborne botulism, symptoms generally begin 18 to 36 hours after eating contaminated food. However, they can occur as soon as 6 hours after or up to 10 days later. Symptoms may include double or blurred vision, drooping eyelids, slurred speech, difficulty swallowing or breathing, paralysis, a thick-feeling tongue, dry mouth, and muscle weakness.

Previous outbreak
It is not the first time Vietnam has dealt with an outbreak of foodborne botulism. In 2020, 12 people in six southern provinces were sick. Cases were also recorded in northern provinces.

A report in the journal Anaerobe described the first recorded cases of foodborne botulism in Hanoi, associated with vegetarian home-canned pâté. A healthy Vietnamese couple, the husband aged 70 and the wife aged 68, fell ill after eating the pâté that was sold online.

Another study, in the Western Pacific Surveillance and Response Journal, said 11 people were in critical condition and required breathing support between July and September 2020.

A history of foods eaten in the four days before illness onset showed all cases had consumed a tinned vegetarian pâté. Clostridium botulinum type B was detected in three opened tins of pâté collected from the houses of patients. In the mouse bioassay for the toxicity of pâté samples, all the mice died with clinical symptoms of botulism. The pâté contained mushrooms, soya beans, and nuts.

Cases ranged in age from 20 to 64 with a median of 38 years old. Eight of the 12 were female and reported having a vegetarian diet. All 11 hospitalized patients required ventilator support but no deaths were recorded. Four serious cases were treated with botulinum antitoxins provided by the World Health Organization (WHO).

A limitation of the work was the inability to determine at which step of the pâté production process contamination was introduced, as the environmental investigation was conducted by another team, and researchers could not inspect the canning company.

“Strengthening of regulation of the production of processed foods and public education on food safety at home are recommended to prevent future foodborne outbreaks,” said scientists.

Overall situation
Another study has revealed more than 3,700 cases of food poisoning in Vietnam from March 2020 to August 2022.

Researchers collected data on food poisoning cases through 184 articles in seven Vietnamese online newspapers. Findings were published in the journal Case Studies in Chemical and Environmental Engineering.

Several types of food such as wild mushrooms, toads, alcohol, pate, seafood, and insects were reported to have caused poisoning cases.

Patients often used wild vegetables, fruits, or mushrooms without being sure of their safety, according to the study. Several cases mentioned drinking alcohol-containing high levels of methanol.