Foodborne Botulism from Barking Deer Meat : Phayao, Thailand, 2006

Abstract

On June 30, 2006, Phayao province reported a cluster of five patients presenting with a similar constellation of neurological signs. An investigation was performed to determine the etiology and source of the outbreak, and to recommend preventive measures. A case - patient was defined as a person in Phu Sang district during 26 June-14 July, 2006 who had, at least, two of following symptoms: paralysis/muscle weakness, dyspnea, blurred vision/diplopia, ptosis, dysarthria, dry mouth and dysphagia. A retrospective cohort study was conducted by reviewing medical records, interviewing cases, and surveying all residents who ate the suspected food. Remaining food, serum and stool of cases were tested for botulism by mouse bioassay, culture and PCR. Environmental survey was conducted around hunting and food preparation processes. Twenty-seven cases were identified. There were no deaths. Male: female ratio was 2:1; median age was 46 years (range: 13-79). The main clinical symptom was dyspnea (78%). All cases had eaten meat from the same barking deer. The times between the consumption and the onset of illness varied from 2 hours to 6 days (mean 36 hours). Eating raw baking deer meat significantly enhanced risk of illness (RR 4.24; 95%CI 1.65-10.84). Deer meat was without cooling or freezing for 23 hours prior to distribution.

Two remaining deer meat samples, serum of two cases and stool specimen of one case were positive for Clostridium botulinum. The remaining barking deer meat was recalled from affected villages. Appropriate food preparation was promoted. Enhanced botulism case surveillance was implemented. No additional cases were detected.