Foodborne botulism outbreaks following consumption of home-canned bamboo shoots in Northern Thailand.
ABSTRACT We report epidemiological investigations of 2 outbreaks of foodborne botulism following consumption of home-canned bamboo shoots in northern Thailand. The first outbreak affecting 4 female and 2 male cases occurred in Mae Sot District, Tak Province, in December 1997. All 6 cases were hospitalized, 4 of whom required mechanical ventilation. All cases experienced neurological features and 4 had gastrointestinal symptoms. One case died, giving a case-fatality rate of 16.7 per cent. A case-control study revealed a significant association (p < 0.01) between the disease and consumption of home-canned bamboo shoots purchased from the same foodshop in the village. The second outbreak of a similar clinical syndrome occurred in Thawangpha District, Nan Province, in April 1998. A total of 13 cases were identified, 9 (69.2%) of whom were female. Nine cases (69.2%) were hospitalized, 4 (30.8%) of whom required mechanical ventilation. Two early hospitalized cases died due to ventilatory failure, giving a case-fatality rate of 15.4 per cent. A case-control study indicated that home-canned bamboo shoots prepared by a local foodshop served as the vehicle for the disease transmission. One bamboo shoot specimen from one affected house was positive for botulinum toxin type A by enzyme-linked immunosorbent assay and mouse antitoxin bioassay. Improper home-canning procedures for bamboo shoot preservation were similarly detected in both outbreaks although performed by different merchants. Prompt recognition and treatment of the disease are essential in reducing the fatality rate. Safe home-canning procedures should be widely distributed and instructed to persons who perform bamboo shoot preservation for sale.
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ABSTRACT: Thailand has had several foodborne outbreaks of botulism, one of the biggest being in 2006 when laboratory investigations identified the etiologic agent as Clostridium botulinum type A. Identification of the etiologic agent from outbreak samples is laborious using conventional microbiological methods and the neurotoxin mouse bioassay. Advances in molecular techniques have added enormous information regarding the etiology of outbreaks and characterization of isolates. We applied these methods in three outbreaks of botulism in Thailand in 2010. A total of 19 cases were involved (seven each in Lampang and Saraburi and five in Maehongson provinces). The first outbreak in Lampang province in April 2010 was associated with C. botulinum type F, which was detected by conventional methods. Outbreaks in Saraburi and Maehongson provinces occurred in May and December were due to C. botulinum type A1(B) and B that were identified by conventional methods and molecular techniques, respectively. The result of phylogenetic sequence analysis showed that C. botulinum type A1(B) strain Saraburi 2010 was close to strain Iwate 2007. Molecular analysis of the third outbreak in Maehongson province showed C. botulinum type B8, which was different from B1-B7 subtype. The nontoxic component genes of strain Maehongson 2010 revealed that ha33, ha17 and botR genes were close to strain Okra (B1) while ha70 and ntnh genes were close to strain 111 (B2). This study demonstrates the utility of molecular genotyping of C. botulinum and how it contributes to our understanding the epidemiology and variation of boNT gene. Thus, the recent botulism outbreaks in Thailand were induced by various C. botulinum types.PLoS ONE 01/2014; 9(1):e77792. DOI:10.1371/journal.pone.0077792 · 3.53 Impact Factor
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ABSTRACT: In this study we describe the electrophysiological findings in botulism patients with neuromuscular respiratory failure from major botulism outbreaks in Thailand. High-rate repetitive nerve stimulation testing (RNST) of the abductor digiti minimi (ADM) muscle of 17 botulism patients with neuromuscular respiratory failure showed mostly incremental responses, especially in response to >20-HZ stimulation. In the most severe stage of neuromuscular respiratory failure, RNST failed to elicit a compound muscle action potential (CMAP) of the ADM muscle. In the moderately severe stage, the initial CMAPs were of very low amplitude, and a 3-HZ RNST elicited incremental or decremental responses. A 10-HZ RNST elicited mainly decremental responses. In the early recovery stage, the initial CMAP amplitudes of the ADM muscle improved, with initially low amplitudes and an incremental response to 3- and 10-HZ RNSTs. Improved electrophysiological patterns of the ADM muscle correlated with improved respiratory muscle function. Incremental responses to 20-HZ RNST were most useful for diagnosis. The initial electrodiagnostic sign of recovery following treatment of neuromuscular respiratory failure was an increased CMAP amplitude and an incremental response to 10-20-HZ RNST. Muscle Nerve 40: 271-278, 2009.Muscle & Nerve 08/2009; 40(2):271-8. DOI:10.1002/mus.21256 · 2.31 Impact Factor
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ABSTRACT: Botulism is a rare presynaptic neuromuscular junction disorder caused by potent toxins produced by the anaerobic, spore-forming, Gram-positive bacterium Clostridium botulinum. Food-borne botulism is caused by the ingestion of foods contaminated with botulinum toxin. In March 2006, there was a large outbreak of food-borne botulism associated with the ingestion of home-canned bamboo shoots in Thailand. The survival analyses for respiratory failure in these patients were studied and are reported here. A prospective observational cohort study was conducted on this outbreak. The primary outcome of interest was the time to respiratory failure. The secondary outcome was the time to weaning off ventilator. The prognostic factors associated with respiratory failure and weaning off ventilator are presented. A total of 91 in-patients with baseline clinical characteristics were included. Most cases first presented with gastrointestinal symptoms followed by neurological symptoms, the most striking of which being difficulty in swallowing. Common clinical features included ptosis, ophthalmoplegia, proximal muscle weakness, pupillary abnormality, and respiratory failure. Forty-two patients developed respiratory failure requiring mechanical ventilation and the median duration on ventilator was 14 days. The median length of hospital stay for all patients was 13.5 days. Difficulty in breathing, moderate to severe ptosis, and dilated and fixed pupils were associated with respiratory failure. Among patients who were on ventilators, a short incubation period and pupillary abnormality were associated with a longer period of mechanical ventilation. All patients had antitoxin injection and there was no mortality in this outbreak. The history of difficult breathing and the findings of moderate to severe ptosis and pupillary abnormality were associated with severe illness and respiratory failure. A long incubation time was associated with a better prognosis. Although botulism is a potentially fatal disease, there was no mortality in this outbreak. All patients had antitoxin injection and good intensive care that resulted in good clinical outcomes.Clinical Toxicology 02/2010; 48(3):177-83. DOI:10.3109/15563651003596113 · 3.12 Impact Factor