An Outbreak of Botulism caused by Bamboo Shoot, Meuang District in Chaiyaphum Province and Sriracha District in Chonburi Province, Thailand, April 2014

Abstract

Background: On 19 April 2014, Bureau of Epidemiology received a notification from the Toxicology Center at Ramathibodi Hospital according to botulinum antitoxin was requested. The requesting was from a private hospital in Chonburi province. After verification, there were 4 suspected cases of botulism who admitted simultaneously at the private hospital Chonburi and Chaiyaphum hospital. Bureau of Epidemiology and local health authorities conducted outbreak investigation of suspected botulism at Chaiyaphum province and Chonburi province during 20 – 22 April 2014. The objectives aimed to confirm diagnosis and outbreak, to identify the source of outbreak and to early containment and recommend the prevention measures.
Methods: We conducted descriptive epidemiological study by interview attending physicians and relatives, review medical records. Active case finding was done in a village where a suspected food was producing. Laboratory investigation was also carried out by collecting serum and stool of the suspected cases. We also collected the bamboo shoot that was left over from the case’s house. All samples both human and food items were sent to the National Institute of Health to grow Clostridium botulinum and to identify the botulinum neurotoxin.
Results: Total 4 cases were met case definition. Three cases were confirmed and another one was probable. Two cases were admitted at the private hospital at Chonburi and were on respiratory support. Another two cases were admitted at Chaiyaphum hospital with oxygen bag with mask support. All four cases were relative. Two cases who were working at Chonburi visited home at Meuang district, Chaiyaphum during Thai New Year holiday. All four cases consumed bamboo shoot preservation in plastic bag on 15 April 2014 at 08.00 -09.00 pm. without cooked with heat. The bamboo shoot was brought from a seller in Nongbuadeang sub-district, Nongbuadeang district, Chaiyaphum. The first case onset was on 16 April 2014 at noon and last case onset was the same day at 10.00 pm. The median incubation period was 20 hours. The clinical presentations in all cases were nausea, vomiting, diarrhea, glossospasm, dysarthria and ptosis. Two cases were respiratory failures. All cases received botulinum antitoxin for 1 day after diagnosis. All cases were recovery without complication. Laboratory results revealed positive culture for C. botulinum in one case and Botulinum neurotoxin type B was detected in 3 cases. The bamboo shoot that left over from consumption was also positive culture C. botulinum and neurotoxin type B detected.
Discussions and Conclusion: We confirmed botulism outbreak and caused by botulinum neurotoxin type B. The source of outbreak was confirmed in bamboo shoot. The contamination might be during process of bamboo shoot preservation. And consumption of uncooked bamboo shoot was also the important risk among these cases. The investigation and control teams recalled the bamboo shoot in the same Lot and destroyed them. We provided education to the people in the village to consume well-cooked bamboo shoot and how to make a bamboo shoot without contamination of soil. After containment, there was no additional case for a month.