The Pasteur Institute has established that food poisoning made 320 school children sick in Kampot province on April 28. A bacteria that occurs naturally in the soil was the culprit, Director Yves Buisson said.
Three teachers and 212 students from Truy Koh Primary School ended up in Kampot provincial hospital last month, complaining of headaches, dizziness and vomiting. Two students were hospitalized for two days; the teachers and others students were released the same day.
Local authorities at first speculated that the students may have been poisoned deliberately, and sent samples to the institute for testing.
An analysis found Bacillus Cereus in the rice that students ate that morning, said Buisson. It was not in the drinking water as some local residents had feared, he said.
This spore-forming bacteria becomes dormant, emerging in humidity and 30 to 40 degree Celsius heat, Buisson said. It then spreads quickly and produces a toxin that may cause nausea, vomiting and even loss of consciousness, he said.
People get sick within two hours of eating, and recover within six hours, Buisson added.
The bacteria will not occur if rice is eaten immediately after being cooked, he said. But it may show up when rice is cooked and left for several hours to cool at room temperature; it will then remain even if the rice is re-heated.
The institute is supervising a field study to determine the circumstances of this food poisoning.