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Botulism From Drinking Prison-Made Illicit Alcohol — Utah 2011

Foodborne botulism is a rare, potentially fatal paralytic illness caused by eating food contaminated by Clostridium botulinum toxin. It occurs most often as a single case not linked to others by a common food source. As a result of improvements in food canning, when outbreaks do occur, they typically involve fewer than five persons. During October 2–4 2011, eight maximum security inmates at the Utah State Prison in Salt Lake County were diagnosed with foodborne botulism. An investigation by Salt Lake Valley Heath Department, Utah Department of Health, and CDC identified pruno, an illicit alcoholic brew, as the vehicle. The principal ingredients in pruno are fruit, sugar, and water. Many additional ingredients, including root vegetables, are sometimes added, depending on the availability of foods in prison. A baked potato saved from a meal served weeks earlier and added to the pruno was the suspected source of C. botulinum spores. Many of the affected inmates suffered severe morbidity, and some required prolonged hospitalizations. Knowing the link between pruno and botulism might help public health and correctional authorities prevent future outbreaks, respond quickly with appropriate health-care to inmates with acute descending paralysis and/or other symptoms, and reduce associated treatment costs to states.

Epidemiologic Investigation

A case of botulism was defined as signs and symptoms of cranial nerve palsies (e.g. double vision, blurred vision, dysphagia, or impaired gag reflex) and weakness, with onset during September 30–October 4, 2011, in a Utah State Prison inmate who had either a clinical specimen positive for C. botulinum (organism or toxin) or a history of consuming the same batch of pruno as an inmate with a positive clinical specimen. Eight inmates had illnesses that met the case definition. Salt Lake Valley Heath Department and Utah Department of Health were notified of a patient with suspected botulism when an inmate at the Utah State Prison was hospitalized at a local hospital (hospital A) on October 2, 2011, with a 3-day history of dysphagia, double vision, progressive weakness, and vomiting. He reported that his symptoms began within 12 hours of drinking pruno. Inmates who had consumed pruno or had symptoms of botulism were urged through a series of announcements and cell-to-cell visits by prison correctional officers and medical staff members to accept medical treatment. The inmates were assured that no punitive actions would be taken if they admitted to drinking pruno. By October 4, an additional 12 inmates sought medical attention for clinical complaints or history of recent pruno consumption. Of the 13 inmates who reported drinking pruno, eight met the case definition by having signs or symptoms compatible with botulism. These eight inmates were admitted to the neuro-critical care unit of hospital A and treated. The other five inmates who drank pruno were evaluated on October 4 by a physician at hospital A and were determined to not have clinical findings consistent with botulism. They were observed in the prison infirmary for 7 days and remained well.

The eight hospitalized patients were aged 24–35 years and lived in close proximity within the same maximum security prison unit. The median time to onset of symptoms was 37 hours after consumption of brew A (range: <12–80 hours). The eight hospitalized patients all drank pruno from the same batch (brew A) on September 30, 2011; in addition, two of the eight drank pruno from a second batch (brew B) on October 2, 2011. Of the five inmates who did not develop botulism, one reported tasting a small amount of brew A, which he spit out, and four reported consuming only brew B. Although most ingredients used in the two brews were the same, a baked potato was included in brew A but not brew B.

Among the eight hospitalized patients, three were placed on mechanical ventilation within 24 hours of admission. The median neuro-critical care unit hospitalization stay was 4 days (range: 2–23 days); time spent in nonprison health-care facilities ranged from 2–58 days. All patients received heptavalent botulinum antitoxin (HBAT), an investigational new drug that is available through CDC (1) and is the mainstay of treatment for noninfant botulism. Because of a misunderstanding at hospital A, informed consent for HBAT administration was not obtained before infusion. HBAT was administered without adverse events and recipients were later informed of its investigational status. After hospital discharge, all eight patients were evaluated in the prison infirmary where they received care for 1–76 days. According to prison medical personnel, most of the inmates continued to have various clinical complaints 11 months after the outbreak, including weakness and loss of muscle mass, dysphagia and reflux. Difficulty sleeping, increased anxiety, and depression also were reported, but did not appear to be from causes other than the botulism incident. One inmate still reported difficulty breathing and another reported double vision. No deaths resulted from the outbreak.

Laboratory Results

Serum, stool, and gastric aspirate specimens collected before antitoxin administration were submitted to the Utah Unified State Laboratory: Public Health and CDC for C. botulinum and botulinum toxin testing. A moist sock used to filter brew A also was submitted for testing at the Utah laboratory. Specimens from five of the eight confirmed patients were positive for C. botulinum type A or its toxin. A small amount of pruno squeezed out of the sock yielded C. botulinum type A.

Field Investigation

Several batches of pruno were reportedly in circulation among inmates at the time of the outbreak. Pruno batch A was made with oranges, grapefruit, canned fruit, water, powdered drink mix (a source of sugar), and a baked potato. Among these ingredients, the baked potato was the only ingredient used in brew A that was not used in simultaneously circulating pruno batches. Consequently, preparation of baked potatoes in the prison kitchen and methods used to prepare brew A were the primary focus of the field investigation.

Investigators performed a systematic retrospective risk assessment, including interviews with food service workers and inspection of the prison kitchen, to determine whether practices that increase the risk for botulism occurred during preparation of baked potatoes. Cooking practices were not observed directly, and no baked potatoes were available for testing. Food service workers reported that baked potatoes were prepared twice a month from raw whole potatoes, and not baked in foil. No other preparation or storage methods that would produce the anaerobic environment necessary for toxin production were identified, making it unlikely that potatoes served to inmates contained toxin.

The inmate who prepared brew A reported the potato was removed from a meal tray, stored at ambient temperature for an undetermined number of weeks in either a sealed plastic bag or jar obtained from the commissary, peeled using his fingernails, and added to a plastic bag containing other ingredients a few days before brew A consumption. The ingredients were fermented in this bag for several days before being distributed to other inmates in resealable plastic bags. Toxin likely was produced when the potato was added to a bag containing low-acidity pruno ingredients under warm, anaerobic conditions during pruno fermentation. Warm conditions commonly are obtained by placing the bagged mixture in warm water and insulating the bag with clothing, towels, or bedding (2). Plastic bags and jars used in pruno fermentation are easily accessible to inmates. Laundry and items purchased from the commissary are delivered in plastic bags and foods packaged in jars and resealable bags can be purchased from the commissary. During the investigation, many types of plastic bags and jars were observed in cells.

In addition to clinical morbidity, the outbreak resulted in considerable cost to Utah taxpayers. These included hospital charges of nearly $500,000; secure emergency transport and correctional facility monitoring at hospital A; and local, state, and federal public health and correctional facility resources for the investigation.

Reported by

Diana Thurston, PhD, Ilene Risk, MPA, Mary B. Hill, MPH, Dagmar Vitek, MD, Linda Bogdanow, Jennifer Robertson, MSPH, Andrea Price, Salt Lake County, Salt Lake Valley Health Dept; Lori Smith, Utah Unified State Laboratory: Public Health. Agam Rao, MD, Div of Foodborne, Waterborne and Environmental Diseases; Janet Dykes, MS, Carolina Luquez, PhD, National Botulism Laboratory Preparedness Team; Maroya Walters PhD, EIS Officer, CDC. Corresponding contributor: Diana Thurston,, 385-468-4198.

Editorial Note

The association between botulism and pruno, an illicit alcoholic beverage often made by inmates, is not well known, and cases of botulism from pruno might be underrecognized. This is the largest outbreak of botulism associated with pruno consumption; two previously reported outbreaks affected one and two inmates, respectively (3). This also is the second largest botulism outbreak in the United States since 2006, surpassed only by a 2007 outbreak attributed to a widely distributed commercial hotdog chili sauce that affected 10 persons (4). Since this investigation, four confirmed cases of botulism among inmates at a federal prison in Arizona were identified on August 3, 2012. As in Utah, potato-containing pruno or food containing leftover pulp from potato-containing pruno was consumed by all four affected inmates and is the suspected vehicle (5).

Botulism is a rare but serious, potentially life-threatening paralytic illness that is a public health emergency because many persons can be sickened by a contaminated food. The classic symptoms of botulism (e.g., blurred or double vision, slurred speech, difficulty swallowing, and muscle weakness) are not unique to botulism. Clinicians who act promptly when botulism is suspected can reduce the associated morbidity and mortality of botulism. The disease and long-term sequelae can be reduced by prompt treatment and HBAT administration. Although the eight inmates sickened by one batch of pruno in this outbreak were identified quickly through active case finding by prison employees, they still required prolonged hospitalizations, including treatment in the neuro-critical care unit, inpatient and outpatient rehabilitation, continued mental health support, and additional medical follow-up. Most of the inmates continued to complain of clinical sequelae 11 months after the outbreak.

Botulism is uncommon because special, rarely obtained conditions are necessary for botulinum toxin production from C. botulinum spores, including an anaerobic, low-salt, low-acid, low-sugar environment at ambient temperatures (6). This investigation, and investigations in California during previous outbreaks, determined that pruno containing potato can provide this favorable environment for botulinum toxin production from C. botulinum. Potatoes and other root vegetables commonly have botulinum spores from the soil on their surfaces (7). Although most batches of pruno reportedly do not contain potatoes, pruno-associated botulism outbreaks all have involved pruno made with potatoes, The addition of potatoes to pruno, therefore, might introduce spores to pruno ingredients. Botulinum spores, however, are omnipresent; although potatoes are the likely source of botulinum spores from outbreaks associated with pruno, other possible sources of contamination include other root vegetables, if added to the brew, and bags used for pruno fermentation. Pruno ingredients commonly include fruits and sugar. When proportion of these ingredients available for inclusion in pruno is less, the pH of the mixture might exceed 4.6 and sugar content might be low, promoting toxin production. Fermentation occurs in the anaerobic environment of a sealed bag, a condition necessary for toxin production.

This outbreak underscores the need for health department and correctional facility awareness of the association between pruno and botulism. Prison health-care providers should notify health departments immediately if they suspect botulism from pruno so that an investigation can begin quickly and botulinum antitoxin requested from CDC immediately. When pruno is the suspected vehicle, case finding strategies should account for the possibility that one pruno batch might be shared among many inmates, even in areas where inmate movements and interactions are highly restricted (e.g., maximum security). Bags, socks, and other equipment used to make pruno might be shared between batches, and pulp left over from pruno might be added to other foods consumed by prisoners. These factors all might increase the number of affected patients. Aggressive case finding in both recent outbreaks enabled timely identification of ill persons. Timely identification is critical to minimizing morbidity, averting fatalities, and minimizing economic burden to states. Prompt HBAT administration can reduce botulism morbidity and mortality. During this investigation, inmates reported that pruno is widely used in correctional facilities throughout the country and is an ingrained part of prison culture. Although illness might be reduced though education of inmates about the association between pruno and botulism, pruno production in prisons likely will not stop.


Richard Garden, MD, Pauline Sturdy, Utah State Prison; Holly K. Ledyard, MD, Pegah Afra, MD, hospital A; Debbie Sorensen, Infectious Disease Bur, Salt Lake Valley Health Dept; Julia Hall, MPH, Rachelle Boulton, MPH, Utah Dept of Health; Joli Weiss PhD, Eric Hawkins, MPH, Arizona Dept of Health Services, Graham Briggs, MPH, Pinal County Public Health Svcs District.


  1. CDC. Investigational heptavalent botulinum antitoxin (HBAT) to replace licensed botulinum antitoxin AB and investigational botulinum antitoxin E. MMWR 2010;59:299.
  2. Gillin E. Make your own pruno and may God have mercy on your soul. The Black Table. September 24, 2003. Available at Accessed November 7, 2011.
  3. Vugia DJ, Mase SR, Cole B, et al. Botulism from drinking pruno. Emerg Infect Dis 2009;15:69–71.
  4. CDC. Botulism associated with commercially canned chili sauce—Texas and Indiana, July 2007. MMWR 2007;56:767–9.
  5. Chan C. 4 Arizona inmates hospitalized; botulism from homemade alcohol suspected. The Arizona Republic. August 27, 2012 Available at Accessed September 26, 2012.
  6. International Commission on Microbiological Specifications for Foods. Clostridium botulinum. In: Micro-organisms in foods 5: characteristics of microbial pathogens. London, UK: Blackie Academic & Professional; 1996:68–111.
  7. CDC. Botulism in the United States, 1899–1996. Handbook for Epidemiologists, Clinicians, and Laboratory Workers. Atlanta, GA: US Department of Health and Human Services, CDC; 1998. Available at Accessed November 7, 2011.

What is already known on this topic?

Foodborne botulism is rare, but it can kill rapidly, and contaminated products might expose many persons. Symptoms of botulism include double vision, blurred vision, drooping eyelids, slurred speech, difficulty swallowing, dry mouth, and muscle weakness. These symptoms are not unique to botulism; prompt treatment and heptavalent botulinum antitoxin (HBAT) administration can reduce botulism morbidity and mortality.

What is added by this report?

This report documents an outbreak of severe illness with prolonged morbidity and great public expense that occurred in a prison from "pruno," alcohol made illicitly by inmates. When a potato or other root vegetable is added to pruno, the risk for foodborne botulism increases. The cost of the outbreak was approximately $500,000 and involved many hours of investigation and prompt hospital treatment. Long-term sequelae, even with prompt treatment, can result.

What are the implications for public health practice?

Preparation of pruno is common in correctional facilities. Public health authorities should know the risk for botulism in correctional facilities and its association with pruno that contains potatoes. When botulism associated with pruno is suspected, state health departments should immediately be notified and more cases should be sought because one pruno batch might be shared among many inmates, even in restricted areas. Timely identification of cases and administration of botulinum antitoxin is critical to minimize morbidity, avert fatalities, and reduce the economic burden to states.

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