From Feb. 13 to 21, Kon Tum villagers banded together in a series of local feasts. But a few days afterward, several people showed signs of fever, vomiting and stomachache.

Two people later died while four others were hospitalized. Dozens of other people also fell sick.

Test results from the National Institute for Food Control later revealed the villagers were infected with the Clostridium botulinum bacteria.

Vo Van Thanh, director of the Kon Tum Department of Health, on Wednesday said the villagers got infected with Clostridium botulinum, the bacteria responsible for producing botulinum, the deadliest neurotoxin known to man.

Due to the large time span and number of meals that transpired, authorities found it difficult to pinpoint exactly what food item was contaminated, said Thanh.

This is not the first time botulinum has been implicated in a food poisoning incident in Vietnam. Last year, at least 16 people suffered from botulism after consuming vegan pate produced by a Hanoi food company. A 70-year-old man died as a result, while several others survived on ventilators for months after.

The company responsible for the mass poisoning, Loi Song Moi, was fined VND17.5 million ($755) for failing to meet food safety standards following the incident. Their products have been recalled nationwide.

Clostridium botulinum produces toxins under low-oxygen conditions. Botulinum toxins are ingested through food in which the bacteria or their spores survive, then grow and produce the toxins.

Symptoms usually appear within 12 to 36 hours, or longer. They include stomachache, fatigue, muscle pain, blurred vision, a dry mouth, difficulty in swallowing and speaking and droopy eyelids. Patients can end up with respiratory failure caused by paralyzed respiratory muscles, or even death.

Except for the more recent cases, Vietnam has not recorded any botulinum poisonings in the past three decades. The country has no antitoxin serum, which has to be imported from abroad.