Botulism from Chopped Garlic: Delayed Recognition of a Major Outbreak

Abstract

Diagnosis of botulism in two teenaged sisters in Montreal led to the identification of 36 previously unrecognized cases of type B botulism in persons who had eaten at a restaurant in Vancouver, British Columbia, during the preceding 6 weeks. A case-control study implicated a new vehicle for botulism, commercial chopped garlic in soybean oil (P less than 10(-4)). Relatively mild and slowly progressive illness, dispersion of patients over at least eight provinces and states in three countries, and a previously unsuspected vehicle had contributed to prolonged misdiagnoses, including myasthenia gravis (six patients), psychiatric disorders (four), stroke (three), and others. Ethnic background influenced severity of illness: 60% of Chinese patients but only 4% of others needed mechanical ventilation (P less than 10(-3]. Trypsinization of serum was needed to show toxemia in one patient. Electromyography results with high-frequency repetitive stimulation corroborated the diagnosis of botulism up to 2 months after onset. Although botulism is a life-threatening disease, misdiagnosis may be common and large outbreaks can escape recognition completely.

Retrospective study of 108 cases of botulism in Poitiers, France

“…In our study, the observed clinical pictures agreed with published descriptions2* 4 7 [20][21][22][23] (table 111). The incubation period varied from 1 to 16 days.…”

An outbreak of foodborne botulism associated with contaminated hazelnut yoghurt

“…Cl. botulinum type B toxin was detected in faeces from one patient but not from patients' sera: in an outbreak of type B botulism associated with chopped garlic, toxaemia was only identified in 3 of 36 patients [15].…”

“…In this outbreak, several of the later cases had mild symptoms and the diagnosis of suspected botulism was not made on initial presentation [12]. It has been suggested in other reports that type B botulism progresses more slowly and is less severe than type A [14,15]. Cl.…”

Wound botulism in drug addicts in the United Kingdom

“…The diagnosis should be confirmed by toxin bioassay, although occasional falsenegatives can occur. Brain and spinal cord imaging may be required to exclude stroke, cord injury and tumour [12].…”