1 fi gure, 3 tables, 1 photo ADVANCEMENT OF THE SCIENCE Outbreak Caused by Clostridium perfringens Infection and Intoxication at a County Correctional Facility Adam E. London, MPA, RS, DAAS Julie A. Payne, MPH Brian Hartl, MPH Kent County Health Department tion, KCHD organized to investigate the suspected outbreak. Abstract Outbreaks of foodborne illness caused by Clostridium perfringens are not usually the result of intoxication and testing of suspected Methods menu items for colony count can often identify the causative item. We Following the report of illnesses on April 16, 2012, KCHD created investigation objec- describe a large outbreak at a county correctional facility in which the data tives to investigate the suspected outbreak by suggest that illness by intoxication contributed substantially to the outbreak: gathering appropriate epidemiological and 29 out of 108 surveyed cases (26.9%) developed symptoms within 2.5 hr of environmental data. The team gathering epi- when meal service began. Inmate testimony further suggests advanced food demiological data consisted of epidemiolo- gists, public health nurses, and sanitarians. decay. Bacterial analyses of food samples indicated a smaller population of C. They developed a questionnaire using the perfringens in the chicken taco meat mixture (<10 CFU/g, enterotoxin positive) KCCF menu for the 72 hr prior to the onset compared with other items. Statistical analyses of food history data provided of the fi rst report of illnesses. Personal interviews were requested with substantially more support for the chicken taco meat mixture as causative inmates due to reported low literacy rates (odds ratio = 55.79, 95% confi dence interval [19.72, 157.83], p < .001) than within that population. KCHD staff con- other menu items. Environmental investigation and testimony from inmates ducted those interviews at the correctional provided additional support implicating the chicken taco meat mixture. facility on April 17–19. A total of 185 inmates, including ill and well individuals, were interviewed. Questions included: sex, age, food consumed, symptoms experienced, Introduction known to be ill at that time. The caller indi- date and onset of those symptoms, duration On April 16, 2012, at 8:30 a.m., the Com- cated that the lunch meal from the prior day of illness, and whether medical care was municable Disease/Epidemiology Unit of the was suspected to be the cause because many obtained. The case defi nition was described Kent County Health Department (KCHD) of the inmates complained about a foul taste as any interviewee reporting vomiting and/ in Grand Rapids, Michigan, received a tele- and odor associated with it. That meal was or diarrhea. Data analyses were performed phone call from an employee of the Kent served to inmates between 10:30 a.m. and using the Epi Info 6 Database Analysis Pro- County Correctional Facility (KCCF). The 12:30 p.m. on April 15 and consisted of a gram from the Centers for Disease Control KCCF employee reported that a foodborne chicken taco meat mixture, rice with cheese and Prevention (CDC). This team also iden- illness outbreak was suspected to be taking sauce, refried beans, and a fl our tortilla. A tifi ed ill inmates who were willing to pro- place at the facility. The caller stated that garden salad with optional salad dress- vide stool samples for laboratory analyses. approximately 30–50 inmates had become ing, yellow cake, and powdered fruit drink Those samples were collected and submitted ill with vomiting and diarrhea after eat- were also offered. According to the caller, to the Michigan Department of Community ing lunch at the facility on April 15, 2012. many people become ill within one hr after Health laboratory for both bacterial analyses The estimate of inmates who were ill later consuming the meal. Other inmates, how- and enterotoxin identifi cation through poly- increased to 250 out of 1,140 inmates as ever, developed symptoms throughout the merase chain reaction (PCR). more information became available. No remainder of that day and into the morning A second work team was charged with employees of the correctional facility were of April 16. Upon receipt of this informa- gathering environmental data from the 8 Volume 80 • Number 1 JEH7-8.17_PRINT.indd 8 6/15/17 3:28 PM ADVANCEMENT OF THE SCIENCE the outbreak was representative of the overall KCCF population (Table 1). TABLE 1 Onset of symptoms ranged from April 15 Profile of Surveyed Ill Respondents at 11:00 a.m. to April 18 at 8:00 p.m. The period of duration between exposure to the Characteristics # % suspect meal and onset of illness ranged from <1 hr to 81 hr, with a mean onset of 9 hr and a Gender median onset of 7 hr. The greatest frequency Female 24 22.22 of illnesses occurred within 1 hr after eating Male 84 77.78 the lunch meal on April 15. As illustrated by the epidemic curve (Figure 1), 29 of the 108 Total 108 ill interviewees (26.9%) reported an onset of Age (year) illness within 2.5 hr of when the lunch ser- 10–19 17 15.74 vice began. No employees of KCCF or of the 20–49 79 73.15 contracted food service company reported ill- ness and none reported consuming the lunch 50–74 9 8.33 meal on April 15. Missing information 3 2.78 Data analyses (Epi Info 6) were utilized Total 108 to evaluate the 60 food items consumed by the KCCF population during the previous 72 hr according to the menu. Odd ratios (OR) Symptoms* # % Respondents and 95% confidence intervals (CI) were cal- Nausea 68 67.3 101 culated and p < .05 was used as a standard for significance. Interviewees were asked to Vomiting 39 38.6 101 indicate if they had consumed each of these Abdominal cramps 96 89.7 107 60 items. ORs for illness related to each of the Diarrhea 94 88.7 106 food items consumed before April 15 were insignificant. Food items consumed on April Bloody diarrhea 14 16.3 86 15 demonstrated statistically significant ORs Fever 24 29.3 85 indicating powerful likelihood of relation- ship (Table 2). The chicken taco meat mix- *Onset: range = <1–81 hr, mean = 9.3 hr, and median = 7 hr. Duration: range = 1–60 hr, mean = 19.13 hr, median = 17 hr. ture demonstrated a substantially greater OR than all other menu items: OR = 55.79, 95% CI (19.72, 157.83), p < .001. KCCF. This team, consisting primarily of teration had occurred. The sheriff’s depart- During the course of the interviews, sanitarians, assessed the food preparation ment and KCHD worked collaboratively to KCHD identified a subgroup of work release and service areas, investigated the history share valuable information essential to each employees with a unique experience. This of the suspect meals, questioned employ- department’s respective investigation. subgroup was presented with the same lunch ees for relevant information, and gathered on April 15 as other inmates, but they had food samples as appropriate. Correctional Results heard from other inmates that there was facilities are not licensed public food ser- something wrong with the chicken taco meat vice operations in the State of Michigan; Epidemiological mixture. The offensive odor of this food item however, the KCHD sanitarians used the Of the 185 surveyed individuals who con- was a common comment from the interview- Michigan Food Law of 2000 (Public Act 92 sumed lunch on April 15, 2012, 108 of them ees. Of the 42 work release employees, only of 2000), the 2005 Food and Drug Admin- were identified as ill according to the case 3 reported eating the chicken taco meat mix- istration (FDA) Food Code, and gener- definition. The survey results demonstrated ture and only 8 (19%) became ill. It should be ally accepted best food safety practices as an overall attack rate of 58.4%. It is, how- noted that the chicken taco meat mixture was guidance for conducting this investigative ever, important to acknowledge that it was often physically in contact with other food inspection. Food specimens were analyzed not possible to interview all inmates and that items on the serving tray. This contact might using PCR for enterotoxin source identifica- sickened inmates may have been more biased have transmitted infectious material and/or tion and incubated for plate count. toward participating in the survey than their enterotoxins from one food item to another It should be noted that the Kent County unaffected counterparts. The actual number in the pre-prepared serving tray. Sheriff’s Department also investigated the cir- of sick inmates likely ranged between 250 Stool specimens were collected from four cumstances associated with the outbreak to (KCCF estimate) and 666 (projection cal- ill inmate volunteers on April 16 and from determine if an act of intentional food adul- culated by survey attack rate). The profile of two additional inmate volunteers on April July/August 2017 • Journal of Environmental Health 9 JEH7-8.17_PRINT.indd 9 6/15/17 3:28 PM ADVANCEMENT OF THE SCIENCE FIGURE 1 Epidemic Curve 16 14 12 Meal served on April 14, 2012, demonstrates 10 contact of items in large serving section. Photo 8 courtesy of Kent County Health Department. Respondents 6 17. Based upon a recommendation by the Survey 4 Michigan Department of Community Health, Ill specimens were sent to their laboratory and 2 analyzed for Bacillus cereus and C. perfrin- gens. All six specimens were found to be 0 0:00 1:00 2:00 3:00 4:00 5:00 6:00 7:00 8:00 9:00 11:00 12:00 13:00 14:00 15:00 16:00 17:00 18:00 19:00 20:00 negative for B.