1. Foodborne botulism from home- canned bamboo shoots Thailand, 1998 Wongwatcharapaiboon P Sriprasert P Leksririvili S Thaikruea L Nanthavas S Thanawong A Thai FETP

2. Acknowledgements Nan Provincial Health Office and Hospital National Institute of Health Armed Force Research Institute of Medical Science US Army Medical Research Institute for infectious Disease Thai FETP

3. Objective Confirm and describe the outbreak Verify diagnosis Identify the source Develop control and prevention strategies Thai FETP To

4. Methodology Reviewed medical records Interviewed patients in the hospital Performed –Active case finding –Case-control study –Laboratory investigation –Environmental survey Thai FETP

5. Case definition Resident of village A or B At least 3 symptoms between April 8 -17, 1998 –Ptosis - Dysphagia –Dysarthria - Dysphonia –Dry mouth - Sore throat –Diarrhea - Vomiting –Symmetrical flaccid paralysis Thai FETP

6. Descriptive results 13 cases with 2 deaths (CFR 15%) –12 (92%) lived in village A –9 (69%) were hospitalized –9 (69%) were female –Median age 44 years (range: 38-68) Thai FETP

7. Clinical manifestations (N=13) Thai FETP

8. Epidemic curve Villages A and B, April, 8-17, 1998 (n= 12) No.ca ses April 1998 Date of onset Thai FETP

9. Epidemic curve Villages A and B, April, 8-17, 1998 (n= 12) No.ca ses Ate breakfast together, April 10 April 1998 Date of onset Thai FETP Family X Family Y

10. Food history of cases (N=13) Thai FETP

11. Case-control study Control definition –Person who participated in cremation of 2 dead cases Thai FETP

12. Case-control study 66 controls, All were female 28 lived in village A Thai FETP

13. Case-control study OR = undetermined Thai FETP

14. Case control study Thai FETP

15. Case-control study OR = 0.03 (95 % CI = 0.00 -0.95) Thai FETP

16. Laboratory result EMG of 2 cases - consistent with botulism Stool culture -negative C. botulinum Home-canned bamboo shoots –negative culture –positive botulinum toxin type A by ELISA and mouse antitoxin bioassay Thai FETP

17. Laboratory result Soil samples from houses surrounding that of the home- canned bamboo shoots manufacturer –negative for C. botulinum Thai FETP

18. Botulism Caused by toxin of anaerobic bacteria Outbreak usually due to home- canned low acid foods ( pH < 4.5) Toxin is heat labile (100 o C, 10 min) Spores are destroyed in 120 o C, 30 min Thai FETP

19. Interventions Prohibited sale of remaining 650 cans Extended loans Educated people to heat bamboo shoots Enforced high temperature processing Strengthened surveillance Thai FETP

20. Discussion Confirmed botulism outbreak Common source –Home-canned bamboo shoots Improper process –Low acid –100 o C Aware of other home-canned foods Thai FETP

21. Limitation Selection of controls –only women Sample not collected under strictly anaerobic condition Thai FETP

22. Recommendation Quality control of home-canned food Clinical and laboratory surveillance –Case and Toxin detection Antitoxin should be available Thai FETP

23. Thank you for your kind attention Thai FETP

24. Why did it not occur in the past? Culture of Thai people ate fresh foods Home canning was promoted in only past 2 years Screening abnormal can –Air detection by percussion –Abnormal smell or taste Depend on chance –To find spores in soils –To wash bamboo shoots incompletely

25. Result of EMG Normal nerve conduction velocities Low amplitude response to single stimulus Decremental trend in amplitude to repetitive low-frequency stimulation (2-5 Hz) Incremental (facilitation) trend to rapid repetitive stimulation (20-50 Hz) Thai FETP