Regional Variations in Home Canning Practices and the Risk of Foodborne Botulism in the Republic of Georgia, 2003

Foodborne botulism is a severe, paralytic illness caused by ingestion of preformed neurotoxins produced by Clostridium botulinum. The acute illness is well described, with cranial nerve dysfunction and symmetric descending flaccid paralysis, potentially progressing to respiratory failure, which in the absence of treatment can lead to death (11). C. botulinum spores are ubiquitous in the environment but germinate under a confluence of circumstances that include anaerobic milieu, low acidity, low salinity, low water activity, and temperature between 3 and 37°C (7). Foodborne botulism is caused by ingestion of foods contaminated with botulinum toxin, which is produced by the growth of C. botulinum or related species under such conditions (2). In several countries, improperly home-canned foods have been identified as important sources of foodborne botulism. The Republic of Georgia (ROG), a former Soviet republic of 4.4 million people, reported one of the highest incidences of foodborne botulism in the world, with home-canned vegetables implicated in 80% of botulism events (12) and a cumulative annual incidence of 5.1 cases per 100,000 individuals in 2004 through 2011 (9). Home canning is extensively practiced in ROG. Botulism events are usually associated with vegetables conserved using a capping device that hermetically seals the lid covering the jar, commonly referred to as a modern method of canning. The traditional method of canning using high concentrations of salt and vinegar is also practiced in ROG, but because this method does not include a capping device that creates anaerobic conditions inside a jar, the traditional method has not been associated with botulism cases. In a previous article presenting national ROG botulism surveillance data, we reported marked regional variations in incidence. In particular, the western part of the country had a significantly lower incidence than did the eastern part (12). This finding prompted us to undertake the present study, in which we conducted a population-based household survey of home canning practices. We then compared home canning practices in regions of high botulism incidence to those in regions of low botulism incidence to identify canning practices that might represent a risk for this disease. This study was conducted in 2003, but the results remain highly relevant today because the incidence of botulism has remained high. Although public health interventions were implemented in response to the original study, the causes of botulism likely remain the same.