The Royal Centre for Disease Control (RCDC) ruled out watermelon as the cause of sickness that got three people admitted to Bajo hospital in Wangdue last week.
Two men and a woman were found unconscious at home after they suffered diarrhoea and vomiting. Watermelon was the food suspect then as all three had consumed the fruit before they got sick.
Samples of leftover watermelon, blood, stool and vomit were sent to the RCDC in Thimphu to confirm the cause of the sickness.
A microbiologist with RCDC, Binay Thapa, said the centre did microbiology analysis where they carried out microbial culture to determine the type of organism in the samples.
Microbial culture is a method of multiplying microbial organisms by letting them reproduce in a predetermined culture medium under controlled laboratory conditions.
Binay Thapa said a bacteria called Staphylococcus aureus was found in the vomitus sample of the woman.
Staphylococcus aureus also called staph is a bacterium that causes infections in different parts of the body.
Staphylococcal food poisoning is an illness of the bowels that causes nausea, vomiting, diarrhoea, dehydration, and abdomen pain. Eating foods contaminated with toxins produced by Staphylococcus aureus causes it. Symptoms usually develop within one to six hours after eating contaminated food.
Binay Thapa said the bacterium usually produces toxin. “It is a localised toxin-induced food poisoning.”
Staph infections may cause disease due to direct infection or due to the production of toxins by the bacteria.
“We did the lab test for the rest of the samples but nothing that could cause the sickness was found in them,” he said. “It is not because of watermelon that three of them got sick.”
Besides the watermelon, he said the other common thing that all three patients ate was a tomato paste pickle.
“Probably it is the tomato paste pickle that is contaminated by the particular bacteria. The contamination could be caused because of poor hygiene while handling the food.”
He said the toxin is heat resistance, which means it cannot be removed even after boiling or cooking.