How Not to Die of Botulism

Highly-poisonous botulinum toxin (the stuff in Botox), played a formidable role in the history of food and warfare. It is still a factor in prison-brewed alcohol and some canned foods, and can quickly kill a person.
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(Andrew Dinh/flickr)

After tanking up on “pruno,” a bootleg prison wine, eight maximum-security inmates at the Utah State prison in Salt Lake County tried to shake off more than just the average hangover. Their buzz faded into double vision, weakness, trouble swallowing, and vomiting. Tests confirmed that the detainees came down with botulism from their cellblock science experiment. In secret, a prison moonshiner mixed grapefruit, oranges, powdered drink mix, canned fruit, and water in a plastic bag. For the pièce de résistance, he added a baked potato  filched from a meal tray weeks earlier and peeled with his fingernails. After days of fermentation and anticipation, the brewer filtered the mash through a sock, and then doled out the hooch to his fellow yardbirds.

The party was short-lived. The potato was a big mistake.

Investigators traced botulism spores to the humble spud. Within hours of the first swig, botulinum toxin infiltrated the prisoners’ nerve cells, causing weakness and paralysis. Three of the men required a breathing tube and ventilator to prevent suffocation. All eight victims received an experimental antitoxin from the Centers for Disease Control and Prevention, and thanks to meticulous supportive care, none died. But recovery from botulism takes weeks to months; the body must regrow new nerve endings to replace the poisoned ones. All told, the hospital bill topped their bar tab—more than $500,000 in fees alone, not including added expenses for transportation, security, and public health investigation.

Botulinum toxin, a protein produced by the bacterium Clostridium botulinum, could be “the most poisonous poison” there is, as writer Carl Lamanna called it in an article for Science, in 1959. First weaponized by Imperial Japan in the 1930s, and later, Nazi Germany, the United States, the Soviet Union, Syria, Iran, Iraq, and North Korea, a single gram of toxin could theoretically kill more than a million people if dispersed into the air and inhaled. But before botulinum toxin became a bioweapon and a smoother of crow's feet as the drug Botox, botulism was historically a foodborne malady, and the toxin lurked in sausage and cured meats.

Botulism, the illness caused by toxin exposure, first received scientific attention in rural Germany in the late 18th century. Officials in Stuttgart saw an increase in “sausage poisoning” in the wake of the Napoleonic wars, possibly due to poor sanitation and widespread poverty. In the 1820s, a young German physician named Justinus Kerner was the first scientist to publish an accurate and comprehensive description of the disease. He analyzed more than 200 cases of suspected sausage poisoning. He fed extracts of these “sour” sausages to animals and described the classic symptoms of botulism. Muscle weakness leading to drooped eye lids, difficulty swallowing, and respiratory failure; altered autonomic nerve function leading to vomiting, pupil dilation, and dry mouth. Brazenly, he sampled a few drops of this extract himself—he survived, though it caused a “great drying out of the palate and pharynx,” a harbinger of Botox’s modern application in treating uncontrollable salivation for those with amyotrophic  lateral sclerosis, or Lou Gehrig’s disease. Grateful citizens dubbed the scientist “Wurst-Kerner,” for his pioneering contributions to public health and sausagery. In 1870, another German physician renamed the illness “botulism” after the Latin word “botulus,” or sausage.

For centuries, people dried, smoked, fermented, canned, and neglected their food, naïve to the microbial threat festering within. This changed in the late 19th and early 20th centuries as science moved from the laboratory into the kitchen. In 1895, Émile van Ermengem isolated a spore-forming bacterium from the remnants of a salted ham that killed three musicians in a Belgian outbreak. He confirmed that Kerner’s mysterious sausage—or ham—poison was made by a microbe. Under very specific growth conditions, the active form of the bacterium could be coaxed to grow and produce toxin; under other conditions, the bacterium would retreat into a dormant, or spore form that does not do so.

Early 20th century researchers found Clostridium botulinum spores nearly anywhere: in soil, rivers, lakes, oceans, on vegetable surfaces, and in fish and animal intestines. Laboratory tests demonstrated that spores are durable: they withstand even boiling. When introduced into an optimal, low-oxygen environment—like the inside of a jar or can of food—spores germinate and make the toxin. Given the ubiquity of botulinum spores in the environment, it is surprising that outbreaks were not more frequent.

As food science matured into its own discipline, botulism outbreaks resulting from commercially canned foods dwindled. Food producers could stop toxin production by manipulating temperature, acidity, salt content, moisture, oxygen concentration, and food preservatives such as nitrates or nitrites. Pressure-cooking freshly canned goods at 250 degrees Fahrenheit destroys spores in 20 minutes, enabling safe long-term storage.

Modern foodborne outbreaks occur when botulism control methods are deliberately, or inadvertently, ignored. Homemade foods are now the leading cause of the disease in the U.S., which is not surprising, as only 59 percent of home canners preserving botulism-friendly low acid vegetables actually use a pressure sterilizing process, according to a National Center for Home Food Preservation survey. Fortunately, botulism remains rare nationwide: between 1990 and 2000, 160 outbreaks afflicted only 263 people. And advances in medical care, including antitoxin availability and intensive care units, have decreased the fatality rate from 60 percent in the first half of the 20th century to about 5 percent now.

But food safety improvements pioneered in the last century occasionally fail the most vulnerable consumers. Young babies now account for most botulism cases reported in the U.S. The cause of infant botulism remains unknown. Infants’ digestive systems are hospitable to Clostridium botulinum, perhaps because their gut bacteria and digestive juices are still immature. Ingested spores activate and produce toxin that is absorbed into the body. Afflicted babies become constipated and “floppy” as the relaxed paralysis takes hold. Like adults, they may require breathing support on a ventilator, but most recover. Early investigators identified honey as a possible spore source in about 20 percent of victims, but most cases remain unexplained—some have wondered whether spore-laden household dust could be the culprit.

Although botulism caused floppy babies for centuries, the first case report of infant botulism was published only in 1976. Around this time, American epidemiologists uncovered another botulism mystery: a geographic one. California, Oregon, Washington, and Alaska accounted for the majority of foodborne outbreaks from 1950 to 1996. They found one answer in Alaska.

For generations, indigenous Alaskans prepared traditional foods using available resources and recipes inherited from their ancestors. To preserve meat, they buried fresh animal parts in cool clay-lined pits to undergo controlled microbial decay under a layer of moss or grass. The final product is complex in flavor, rich in nutrients, portable, and safe from scavengers—no cooking needed! Scandanavians historically used a similar process to make gravlax, which literally translates to “grave salmon.” We now know that traditional preserved meats like seal, whale (“muktuk”), beaver tail (“stink tail”), and salmon heads (“stink heads”) can nurture Clostridium botulinum, much like Kerner’s sausage.

In the far North, as in Europe, foodborne botulism is nothing new. In 1913, explorer Vilhjalmur Stefansson reported a suspected botulism outbreak of “white whale poisoning” that killed eight Inuit. Alaskan botulism rates skyrocketed in the 1970’s and 80’s while remaining steady nationwide. This trend was likely caused by changes in food preservation practices, though better record keeping and detection of the illness probably contributed. As Alaska modernized, “stink” chefs substituted breathable earthen pits or animal skins with readily sourced vessels made of wood, glass, or plastic. New containers facilitate fast indoor fermentation without the hassle of digging. Better living through chemistry? Perhaps not. Investigators suspect that these well-sealed containers create a warm, oxygen-deprived environment more hospitable to botulinum spores.

In response to the botulism epidemic, Alaskan tribal and public health officials launched an educational campaign encouraging citizens to return to the traditional meat preservation methods of their forebears. Their message is counterintuitive—who could imagine that burying meat in the ground is less harmful than sealing it in a clean bucket? Some are heeding the advice, as Alaskan foodborne botulism is at its lowest since the 1960’s, despite remaining more than 800 times the national average. Declining popularity of “stink” foods could also  be contributing to the decline. Nonetheless, the Alaskan botulism experience serves as a culinary “I told you so” to younger generations. Sometimes, you shouldn’t mess with the recipe.

Much like native Alaskan cuisine, prison brewing has a storied tradition. The recipe is simple: All you need is a carbohydrate (sugar or starch), a spirit of adventure, and time. Pruno owes its name to the dried prunes historically used as a sugar source. Natural airborne yeasts, or those “back-slopped” from a prior batch, ferment the carbohydrate into alcohol. This is hastened by heating. Prison brewers will steep bags of young pruno in hot water and swaddle them in blankets for insulation. Carbohydrate choice is limited only by resources and creativity: potatoes, fresh fruit, fruit cocktail, raisins, prunes, sugar packets, ketchup, yams, jello, honey, corn, rice, bread, jelly, cake frosting, and hard candies have all been used.

Pruno causes headaches for drinkers and wardens alike, as corrections officials struggle to balance inmate nutrition with order. Tipsy prisoners are more likely to brawl. In 2002, the Los Angeles Times reported that the maximum-security state prison in Lancaster, California banned fresh fruit from the lunches delivered to each inmate’s cell in order to discourage pruno brewing, though prisoners continued to receive at least 15 servings of fresh fruit each week under observation in the cafeteria. Given nutritional needs and the availability of sugar sources, one official lamented, “It’s pretty much an unwinnable battle.”

Lukewarm pruno, low in acid, salt, and oxygen, is a paradise for C. botulinum. Spores can contaminate the brew in any number of ways, but in the case of the 2011 Utah outbreak, epidemiologists fingered the baked potato. Similar potato-borne pruno outbreaks occurred in California state prisons in Riverside County in 2004 and Monterey County in 2005, and twice in Pinal County, Arizona in 2012. In the outside world, improperly baked potatoes cause occasional restaurant botulism outbreaks. These episodes often involve potatoes baked in aluminum foil, as foil insulates the durable C. botulinum spores from lethal cooking temperatures. When the wrapped potatoes are removed from the oven, the stressed—but intact—spores germinate to produce toxin in the moist, warm, airtight environment.

The long-recognized relationship between baked potatoes and botulism earned the troublesome tuber a classification as a “potentially hazardous food” in the Food and Drug Administration’s Food Code. Potatoes, like C. botulinum, grow in the soil, and botulinum spores seem quite at home on their surface. Proper cooking and storage kills spores and inhibits toxin formation. In the case of the Utah outbreak, spores probably germinated in the warm, sealed container during the “undetermined number of weeks” the potato spent in hiding prior to being used in pruno. In response to multiple botulism outbreaks from potato-based pruno, the Arizona State Prison Complex-Eynman banned potatoes from prison meals.

Food and drink have been cohabitating with C. botulinum as long as humans have been sealing them in containers. With safe prepared food on every supermarket shelf, it is easy to forget that civilization had to learn the fundamental lessons of food storage the hard way—through sausage and white whale poisoning. As local food sourcing grows in popularity, more environmentally and health conscious Americans are surrendering their Oscar Meyer for the home pickled, smoked, canned, dried, and fermented foods of generations past. As they rediscover the richness, independence, and simplicity of do-it-yourself cuisine, they must not forget the lessons of Kerner, van Ermengem, and the early pioneers of food microbiology.

In the 20th century, government oversight of commercial meat production undoubtedly saved lives. Botulism outbreaks are now headline-grabbing events, rather than just another day in Stuttgart. Though today, many aspiring restaurateurs and meat curers feel stifled by the rigorous certification process required by local and federal food safety inspectors before they can legally sling their salami to the public. Under the current system, regulators set standards, and producers must prove that their products meet them.

Underground Meats, a Wisconsin meat curer and culinary sibling of Forequarter, a James Beard semi-finalist restaurant, proposes an innovative solution. With more than $49,000 raised on the fundraising website Kickstarter, underground meatmaster Jonny Hunter aims to develop and publish an open-source food safety plan for the production dry-cured salami. This plan, known as a “Hazard Analysis and Critical Control Points,” proves to regulators that a recipe is safe. In the artisan salami world, HACCP’s are typically closely guarded industry secrets, given the time, money, and scientific resources invested in their development.

Hunter aims to “make our local food more accessible and safe.” To stifle harmful bacteria, Underground Meats employs a strategy of acidity changes, controlled drying, and addition of nitrates to directly kill any remaining bugs including C. botulinum. “Nitrate-free” and “no nitrite added” meats, Hunter adds, are a “huge hoax,” as they are made with celery powder—an alternative source of nitrates, albeit not labeled as such. “We believe food safety information should not be proprietary. If someone has a better idea about how a process can limit food borne illness, that information should be free for everyone to access.” He continues, “Open source could be a great model in increasing the food safety knowledge in this community and I hope it is one that sticks.” Somewhere in Sausage Heaven, Justinus Kerner is smiling.

Over time, changes in cooking and food storage trends periodically reinvent man’s relationship with botulism. Be it canned corn or muktuk, the basics of botulism control—careful attention to salt and water balance, moisture, acidity, temperature, and oxygen content—stay the same. C. botulinum is no feral beast: it is a creature of habit, though fortunately, a rare one. Adherence to time-vetted recipes and practices can prevent a trip to the intensive care unit.

So the next time your buddy offers you a cup of room-temperature pruno, politely decline. If you really got a hankerin’, at least make sure he skipped the potato.

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Bradley Wertheim, MD, is an internal medicine resident at the Massachusetts General Hospital in Boston.

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