Botulism in the North: A Disease Without Borders

(See the article by Fagan et al, on Pages 585–592) It has now been 50 years since Dolman [1] reviewed type E botulism in Arctic and subarctic regions. As Dolman reported, records of foodborne illness among North American aboriginal peoples date back to Stefansson's descriptions of “white whale poisoning” in his expedition to the Mackenzie River delta [2]. Upon returning to the Mackenzie delta, Stefansson found that a group of 8 of his acquaintances “had been poisoned by eating the meat of a freshly killed white whale.” Botulism after consumption of traditionally prepared foods has been reported in coastal areas of the North including Alaska, the Pacific coast of British Columbia, northern Canada (Yukon, Northwest Territories, Nunavut, Nunavik, and Labrador), and Greenland [3–12]. The majority of botulism outbreaks in Alaska, northern Canada, and Greenland have been caused by consumption of the flesh of marine mammals and fish. Traditionally-aged meats called igunaq have been frequently implicated in botulism cases among the Canadian Inuit population. The traditional preparation involves placing meat and fat tissues into skin bags (puurtaq), which are sewn shut and aged for weeks or months under rocks or buried under gravel [13]. However, it has become common practice in the Nunavik region and elsewhere to use either plastic bags or buckets, metal barrels, or glass containers in place of the skin pouch. Among Pacific coast First Nations people and Alaska Natives in southeast Alaska, foodborne botulism is caused by salmon eggs (“stink eggs”) aged in airtight jars [4, 7, 12, 14, 15]. While traditionally prepared northern foods are often incorrectly referred to as being “fermented,” they are not actually fermented. Fermentation requires a carbohydrate substrate and results in organic acid production with a subsequent reduction in pH. Fermentation has been used as a safe method of food preparation for millennia. Since the meat, fat, and skin of marine mammals contain very little fermentable carbohydrates, fermentation does not occur and the pH remains neutral. This aging process is rather a putrefaction or advanced decomposition of proteins and fat that allows growth of Clostridium botulinum (type E strains are inhibited at a pH of ≤5) and production of botulinum neurotoxin. As Fagan et al [16] note, contamination of seal meat could occur during butchering, particularly when tissues are cut and placed in contact with the shoreline soil or rocks. In Alaska, spores of C. botulinum type E are widely distributed along the coast and have been isolated near locations where botulism outbreaks have previously occurred [17]. C. botulinum type E has been found in high incidences in other northern areas where botulism is endemic, including 86% of samples from the marine environment of Greenland [18] and 88% of samples of shoreline soils from the Ungava Bay region of Quebec [19]. Marine mammals may also be a possible source of C. botulinum spores [20]. The mean annual number of cases per population among Alaska Natives appeared to increase during the 1970s and 1980s, reaching a peak in 1990–1994. Could this be an apparent increase resulting from more thorough identification and reporting of incidents since 1970, or has it resulted from changes in food preparation practice? Decreasing incidence of botulism cases since the late 1990s might be attributed to decreasing consumption of traditional foods by younger Alaska Natives. Fagan et al [16] report that the incidence of botulism was greatest among Alaska Natives aged ≥60 years. This agrees with studies indicating that traditional foods are eaten more frequently by older Alaska Natives [21, 22]. Dolman [1] recognized in 1960 that control of botulism in the Arctic and sub-Arctic is “mainly a problem of education in public health.” The summary presented by Fagan et al [16] in this issue of Clinical Infectious Diseases is important work that should aid in the development of educational materials to reduce the incidence of botulism in Alaska. The limited population affected by botulism in the North could allow targeted education to make a large impact on the incidence of botulism. Hauschild and Gauvreau [7] reported a decrease in cases among the First Nations population of coastal British Columbia that was attributed to efforts of public health agencies to discourage the consumption of traditionally prepared salmon eggs. Fagan et al [16] have recommended that educational materials should be disseminated to women and elders because they are more exposed to the disease. Local producers of aquatic-game foods should also be informed on how to minimize contamination during the butchering process and prevent growth and toxin production of C. botulinum type E during aging. In northern Canada, some of these traditionally prepared foods may be sold in a food store by local producers, but generally they are shared locally among family members and friends or with persons from other neighboring villages (intercommunity trade). Traditional foods contribute both nutritional and cultural benefits to the Canadian Inuit who consume them. Key nutrients provided to the diet by “country foods” include iron, zinc, vitamins A and E, and sometimes vitamin C. Marine mammal blubber, a traditional food eaten by Canadian Inuit, is an important source of omega-3 fatty acids. Rather than discourage consumption of traditional foods, it would be preferable to identify high-risk meat-handling practices to reduce the incidence and extent of contamination of marine mammal meat, yet allow the continuation of traditional customs and practices. Boiling aged aquatic-game foods is not an acceptable option for consumers who prefer the traditional taste of this delicacy, and hence efforts should be directed at controlling growth of C. botulinum type E to prevent development of toxigenesis. Culturally appropriate educational materials focusing on safer traditional fermentation processes have been prepared by the Alaska State Department of Health, in partnership with the Centers for Disease Control and Prevention [23]. While it has been suggested that use of plastic and glass containers, rather than traditional skin containers, may provide an environment more conducive to growth of C. botulinum [21, 24], this has not been experimentally shown. Storing food preparations at temperatures of <3°C, below the minimum growth temperature of C. botulinum type E, during the aging process should reduce the risk associated with traditional foods. Potential conflicts of interest. All authors: no conflicts.