An outbreak of Norwalk-like viral gastroenteritis in a frequently penalized food service operation: a case for mandatory training of food handlers in safety and hygiene.

In 1999, in Toledo, Ohio, an outbreak of gastroenteritis occurred among people who had attended a Christmas dinner banquet and had eaten food prepared by a local caterer. Overall, 93 of the 137 attendees (67.9 percent) reported illness. Eight sought medical care, and one was hospitalized. Case-control studies revealed that the illness was associated with eating tossed salad (odds ratio [OR] = 2.5, 95 percent confidence interval [CI] = 1.02-6.26). Eleven of 12 stool specimens that were taken from ill people tested positive for a Norwalk-like virus (NLV) but were negative for E. coli O157:H7, Salmonella, and Shigella. The primary source of the outbreak was not determined, but an infected food handler may have played a role in the transmission of the virus. The catering facility had been cited frequently for food safety and hygiene violations. None of the personnel or food handlers at this facility had been appropriately trained in safe food-handling practices, nor had the personnel at another local caterer that had prepared food items suspected of causing a multistate outbreak of NLVs. In Toledo, food service operations with trained personnel/food handlers received better inspection reports than food service operations without trained personnel and were less likely to contribute to foodborne outbreaks. Training of personnel and food handlers may be important for preventing outbreaks.     

Food-borne outbreak of Giardia lamblia.

An outbreak of giardiasis occurred following a family party for 25 persons. Nine who had eaten fruit salad became ill, compared with one who had not eaten the salad (Relative Risk = 7.4, 95% CI = 1.4, 169.3). The fruit salad preparer had a diapered child and a pet rabbit at home who were both positive for Giardia lamblia. This outbreak emphasizes the importance of good hygienic practices in food preparation and the possibility of domestic-animal-to-person transmission in Giardia outbreaks.     

Risk factors for typhoid fever among adult patients in Diyarbakir, Turkey

We conducted a case-control study to assess risk factors for typhoid fever in Diyarbakir, Turkey, a region where transmission of Salmonella typhi is endemic. We prospectively identified febrile patients from Diyarbakir and the surrounding area who were admitted to hospital. Cases were defined as patients who had S. typhi isolated from at least one blood culture. Sixty-four cases with blood culture-confirmed S. typhi were identified between May 2001 and May 2003. In total, 128 age- and sex-matched controls selected from neighbourhoods as cases were enrolled. We hypothesized that consumption of raw vegetables contaminated with sewage would be associated with an increased risk of typhoid fever. Conditional logistic regression modelling revealed that living in a crowded household (OR 3.31, 95% CI 1.58-6.92, P=0.002), eating cig kofte (a traditional raw food) (OR 5.29, 95% CI 2.20-12.69, P=0.000) and lettuce salad (OR 3.55, 95% CI 1.52-8.28, P=0.003) in the 15 days prior to symptoms onset was independently associated with typhoid fever. We conclude that living in a crowded household and consumption of raw vegetables outside the home increase the risk of typhoid fever in this region.     

A foodborne outbreak of Campylobacter jejuni (O:33) infection associated with tuna salad: a rare strain in an unusual vehicle.

We report a foodborne outbreak of Campylobacter jejuni infection in a summer camp. Outbreak-related cases occurred in 79 persons including 3 secondary cases in campers. Campylobacter jejuni was isolated from stool specimens from 16 of 21 patients who submitted a sample; 13 viable isolates were serotyped and all were serotype O:33 (somatic O scheme) or HL:18 (heat-labile scheme), and biotype III (Lior scheme). This serotype is widely distributed geographically but rarely isolated from humans. Samples of water from the wells supplying the camp were negative for faecal coliforms, and raw milk had not been served in the camp. A matched (1:1) case-control study identified tuna salad served for lunch on 19 July as the likely food item associated with illness (matched odds ratio=22; 95% confidence intervals (CI)=3.6-908). Swimming in the camp pool and other recreational water use in area lakes by the campers were not statistically associated with illness. The precise mechanism of introduction of the organism into the tuna salad remains unknown; contamination most likely occurred through cross-contamination with another food product, the hands of a food handler, or a work surface. Several deficiencies in the operation of the camp kitchen were identified. In Wisconsin, kitchens of such camps are subject to different inspection rules than restaurants. Camp staff, administrators, counselors, food managers, and infirmary staff, should fulfil important roles in their respective areas to prevent future outbreaks.     

Outbreak of Shigella flexneri linked to salad prepared at a central commissary in Michigan.

In August 1992, the Michigan Department of Public Health was notified of a cluster of persons with Shigella flexneri infections, all of whom had eaten at different outlets of a single restaurant chain. The chain prepared many foods at a central kitchen. A matched case-control study to determine risk factors for illness among patrons of the restaurant chain was undertaken. An inspection of the commissary and a review of commissary inspection and employee records were conducted. Of the 46 patients identified, 44 had eaten tossed salad versus 33 of the 71 controls (matched odds ratio = 56.9; 95 percent confidence interval 5.0, 648.1). Improper salad preparation techniques were used, and the salad preparation area had not been inspected in several years. Some salad preparers had been ill shortly before the outbreak but continued to work. The greater use of central kitchens could lead to larger outbreaks of illness related to improper food handling. Raw vegetables are a potential vehicle for transmission of shigellosis. Coordination of all agencies responsible for inspecting commissaries should be assured. Assuring restriction of ill food handlers will require management to take an active role in identification of ill employees and in the development of incentives to report illness.     

Mass sociogenic illness in a youth center.

In July, 1989, 63 (42%) of 150 children ages 4-14 years attending an outreach program at a youth center in Florida, but no employees, developed acute and rapidly resolving upper gastrointestinal symptoms 2 to 40 minutes after a prepackaged lunch. All ill children were sent to 3 local hospital emergency departments for evaluation. However, clinical evaluation was normal for all. Of 102 children who ate any prepackaged foods, 48 (47%) became ill compared to 1/19 (5%) for children who did not eat (rate ratio [RR] = 8.9; 95% confidence interval [CI]: 1.3-60.9). No employees ate any of the food items served. Consumption of sandwiches was associated with a moderate increased risk of illness (RR = 1.7, 95% CI: 1.0-2.9). The attack rate did not differ by age, but was greater for girls (39/56, 70%) than for boys (9/46, 20%; [RR = 3.6, 95% CI: 1.9-6.6]). Over 3,000 similar prepackaged meals from the same caterer were served in the same area of Florida that day. An inquiry in the area documented absence of similar symptoms elsewhere. Unopened meal samples tested negative for pesticide residues, heavy metals, staphylococcal toxin, or Bacillus cereus. We diagnosed the outbreak as mass sociogenic illness. Complaints of a bad tasting sandwich by the index case and possible staff anxiety about food poisoning may have contributed to the development of the outbreak.     

Outbreak of adenoviral infections in a long-term paediatric facility, New Jersey, 1986/87.

During an 8-week period in the winter of 1986-87, there were 11 deaths from an adenovirus infection (case fatality rate = 39%, 11/28) in a long-term care paediatric facility in southern New Jersey. Among the 61 resident children, all with severe congenital and/or acquired disabilities, 28 developed a febrile respiratory illness compatible with adenovirus infection [attack rate (AR) = 46%]. Patients with tracheostomies were three times as likely to become ill [relative risk (RR) = 3.2, 95% confidence intervals (CI) = 1.8-5.6]. Twenty-three members of the staff had a similar febrile illness (AR = 22%, 23/106); nurses were more likely to be ill than other staff (RR = 3.0, 95% CI = 1.1-11.4). Adenovirus 7 was isolated from four of the case patients and adenovirus 1 from one. The findings suggest prolonged transmission between patients and nursing staff with lack of cohorting of ill patients probably contributing to the prolongation of the outbreak. This investigation indicates that adenoviral outbreaks, although rare, can have a high mortality in severely disabled children, and that future outbreak investigations should examine the use of vaccines or antiviral agents to reduce mortality and for outbreak control.     

Food Insecurity and Risk of Depression Among Refugees and Immigrants in South Africa

South Africa’s refugee population has grown considerably over the last decade. Both food insecurity and mental illness are common in developing countries, but this relationship remains unexamined in an African refugee population. 335 adult refugees in Durban, South Africa were interviewed using a self-report of food insecurity and the Hopkins Symptom Checklist-25. The proportion of those who responded ‘often true’ to not having enough food and eating less was 23.1 and 54.3 %, respectively. The proportion of individuals with a significant level of anxiety and depressive symptomatology was 49.4 and 54.6 %, respectively. The adjusted logistic regression indicated that not eating enough was significantly associated with anxiety (aOR = 4.52, 95 % CI: 2.09–9.80) and depression (aOR = 4.51, 95 % CI: 2.01–10.09). Similarly, eating less was significantly associated with anxiety (aOR = 2.88, 95 % CI: 1.56–5.31) and depression (aOR = 2.88, 95 % CI: 1.54–5.39). The high prevalence of food insecurity, and its relationship to mental illness, highlight the importance of addressing basic needs among this population.     

Risk factors for secondary transmission in households after a common-source outbreak of Norwalk gastroenteritis

In November 1984, a foodborne outbreak of Norwalk gastroenteritis occurred in a K-12 public school in northern Vermont. The outbreak offered an opportunity to systematically study in detail secondary transmission rates in households. Eating salad at Tuesday's school-sponsored Thanksgiving Banquet was associated with illness among students and staff members (p less than 0.025). Seven of 11 serum pairs from ill persons showed a fourfold or greater rise in antibody titer to Norwalk virus compared with one of nine controls (p = 0.028). The study of secondary household transmission revealed that households with persons with primary illness were 5.5 times more likely to experience secondary illness than households with well school children or adults. As the number of individuals with primary illness in the household increased, the secondary illness rates increased. Pre-school children were twice as likely as adults to develop secondary illness.     

An outbreak of shigellosis at an outdoor music festival

In August 1988, an estimated 3,175 women who attended a 5-day outdoor music festival in Michigan became ill with gastroenteritis caused by Shigella sonnei. Onset of illness peaked 2 days after the festival ended, and patients were spread throughout the United States by the time the outbreak was recognized. An uncooked tofu salad served on the last day was implicated as the outbreak vehicle (odds ratio = 3.4, p less than 0.0001). Over 2,000 volunteer food handlers prepared the communal meals served during the festival. This large foodborne outbreak had been heralded by a smaller outbreak of shigellosis among staff shortly before the festival began and by continued transmission of shigellosis from staff to attendees during the festival. S. sonnei isolated from women who became ill before, during, and after the festival had identical antimicrobial susceptibility patterns and plasmid profiles. Limited access to soap and running water for handwashing was one of the few sanitary deficits noted at this gathering. This investigation demonstrates the need for surveillance and prompt public health intervention when Shigella infections are recognized in persons attending mass outdoor gatherings, the singular importance of handwashing in reducing secondary transmission of shigellosis, and the potential for explosive outbreaks when communal meals are prepared by large numbers of food handlers.     

An outbreak of infections with a new Salmonella phage type linked to a symptomatic food handler.

In December 2001, the South Australian Communicable Disease Control Branch investigated an outbreak of gastrointestinal illness linked to a Korean style restaurant in metropolitan Adelaide. Twenty-eight people were identified as having experienced gastrointestinal symptoms subsequent to dining at the restaurant between 9 and 12 December 2001. A case-control study implicated mango pudding dessert (OR 16.67 95% CI 2.03-177.04) and plain chicken (OR 10.67 95% CI 1.04-264.32). Nineteen cases and one food handler submitted faecal specimens that grew Salmonella Typhimurium 64var. Two samples of mango pudding and one sample of pickled Chinese cabbage also grew Salmonella Typhimurium 64var. The infected food handler reported an onset of illness 2 days before cases first reported eating at the restaurant. The food handler's only role was to prepare the mango pudding dessert in an area external to the restaurant's kitchen. Illness was strongly associated with consumption of a contaminated mango pudding dessert, with contamination most likely resulting from the symptomatic and culture positive food handler who prepared the dish. This outbreak demonstrates the importance of excluding symptomatic food handlers, and the need for appropriately informing and educating food handlers regarding safe food handling procedures. Restaurants with staff and management from non-English speaking backgrounds should be specifically targeted for education that is both culturally sensitive and language specific.     

北京市某敬老院一起食源性嗜水气单胞菌急性胃肠炎暴发调查

目的调查北京市某敬老院出现多名急性胃肠炎病例的感染来源、传播途径和致病因素。方法应用流行病学描述性分析、队列研究、现场卫生学调查以及实验室检验对暴发原因进行综合分析,判断可能的致病因素。结果该敬老院住院老人和职工均有发病,罹患率为15．2％（77／506）,各职业罹患率无显著差异。不同楼层收住老人的自理能力有所不同,自理能力强、能自主摄人凉拌菜的老人比自理能力弱、不能自主摄入凉拌菜的老人罹患率高,差异有统计学意义（P〈0．05）。调查8月21日早餐凉拌菜的暴露情况,暴露组罹患率为28．1％（76／270）,非暴露组为0．4％（1／236）,RR=66．4（95％CI：9．31-474．02）。在某些剩余食品、病例粪便、餐具涂抹及外环境涂抹中均检出嗜水气单胞菌。结论该次暴发疫情是由于摄人了被嗜水气单胞菌污染的凉拌菜引起的,建议敬老院对食堂外环境、加工工具进行彻底消毒,注意凉菜加工工具和储藏环境生熟分开。     

广州市城区小学二年级学生家庭在外就餐频次与学生肥胖的关系

目的 了解广州市城区小学二年级学生的家庭在外就餐现状及其影响因素,并分析其与儿童超重肥胖的关系。方法 抽取广州市12所小学的二年级学生2 206名,进行问卷调查和体格检查。应用logistic回归模型分析家庭在外就餐的影响因素及其与儿童超重肥胖的关系。结果 学生家庭在外就餐≥1次/周者占53.99%。多因素分析显示,独生子女家庭比非独生子女家庭有更高的可能性在外就餐（OR = 1.45,95% CI:1.18～1.78,P＜0.001）。与家庭人均月收入＜5 000元的家庭相比,收入高的家庭在外就餐的可能性更高（家庭人均月收入为5 000～9 999元:OR = 1.60,95% CI:1.21～2.13,P = 0.001;≥10 000元:OR = 2.22,95% CI:1.68～2.94,P＜0.001）。类似,与父母文化程度为高中及以下的家庭相比,父母文化程度为大专或本科的家庭有更高的在外就餐可能性（OR = 1.87,95% CI:1.44～2.43,P＜0.001）。而中等营养知识得分的家长较得分高的家长有减少带孩子外出就餐的倾向（OR = 0.75,95% CI:0.59～0.95,P = 0.016）。此外,家庭在外就餐与儿童超重肥胖风险增高存在统计学关联（OR = 1.31,95% CI:1.03～1.67,P = 0.032）。结论 广州市城区小学二年级学生家庭在外就餐现象较为普遍。独生子女家庭、家庭收入和父母文化程度和营养知识水平是家庭在外就餐的影响因素。家庭在外就餐可能会增加儿童超重肥胖的风险。     

Influence of Behavioral and Environmental Factors on the Development of Obesity in Three-year-old Children —A Case-Control Study Based on Toyama Study—

Obesity in children seems to be a risk factor for chronic diseases in adulthood. From the viewpoint of preventive medicine, factors influencing the development of obese children should be removed early in life. The purpose of this study was to the elucidate relationship between obesity in 3-year-old children and both behavioral and environmental factors by conducting a case-control study. Subjects were selected from the Toyama study. Matched-pair comparisons were performed between obese children whose Kaup’s index was 18 or more (N=117) and control children (N=234) . Multivariate stepwised logistic regression analysis also applied to assess influence of confounding factors. The results indicated that the following 6 factors significantly influenced the development of obese 3-year-old children in exact Fisher’s method analysis (p<0.05): person other than the mother responsible for taking care of the child, short sleep duration (9 hours or less), physical inactivity, eating snacks irregularly, overweight father (BMI≥24), and overweight mother (BMI≥24). For both sexes, after adjusting for confounders by multivariate stepwise logistic analysis, overweight mother (OR 2.54, 95 % CI 1.64-3.95), birth overweight (birth weight≥3,500g; OR 1.76, 95 % CI 1.15-2.69), the mother not responsible for taking care of the child (OR 1.65, 95% CI 1.10-2.48), overweight father (OR 1.62, 95%CI 1.09-2.40), eating snacks irregularly (OR 1.56, 95% CI 1.04-2.33), and gender (female;OR 0.51, 95% CI 0.34-0.77) had significant relationships with obesity in childhood. For boys, overweight mother (OR 2.53, 95 % CI 1.47-4.35), birth overweight (OR 2.03, 95%CI 1.22-3.39), eating snacks irregularly (OR 1.94, 95 %CI 1.19-3.18), and birth month (36-41 months; OR 0.47, 95 % CI 0.23-0.96) had significant relationships. For girls, overweight mother (OR 2.62, 1.28-5.35), and short sleep duration (OR 2.24, 1.11-4.52) had significant relationships. In neither Fisher’s exact method nor multivariate logistic models, time to wake up, bedtime, duration of playing outdoors, regularity of meals, care about salty food, or frequency of eating snacks had significant relations with obesity in 3-year-old children (p<0.05).     

Large outbreak of Salmonella enteritidis PT8 in Portsmouth, UK, associated with a restaurant

Seventy-five individuals with Salmonella infection were identified in the Portsmouth area during August and September 2009, predominantly Salmonella Enteritidis phage type 8. Five patients were admitted to hospital. A case-case comparison study showed that a local restaurant was the most likely source of the infection with a risk of illness among its customers 25-fold higher than that of those who did not attend the restaurant. A case-control study conducted to investigate specific risk factors for infection at the restaurant showed that eating salad was associated with a threefold increase in probability of illness. Changing from using ready washed lettuces to lettuces requiring washing and not adhering strictly to the 48 hours exclusion policy for food handlers with diarrhoea were likely to have contributed to the initiation and propagation of this outbreak. Possibilities for cross-contamination and environmental contamination were identified in the restaurant.     

Person-to-person transmission in an outbreak of enteroinvasive Escherichia coli

In the summer of 1981, an outbreak of diarrhea occurred in students and staff at a school for mentally retarded adults and children in Columbia, Missouri. Forty-one (48%) of 86 students and 38 (28%) of 137 staff members in the two dormitories with the lowest functioning students were ill. Enteroinvasive Escherichia coli 0124:H30 was isolated from 20 persons including six staff members, 13 students, and the ill mother of one of the students. Contact with students was associated with illness. Thirty-eight (33%) of the 115 student-care staff members and none of the 22 nonstudent-care staff members who worked in the two dormitories were ill (p = 0.004, chi-square). In the dormitory with the most dependent students, illness in student-care staff was associated with the number of contacts with ill students and with having taken a student home during the outbreak. Control measures to interrupt transmission included separation of symptomatic or culture-positive students from those who were well, and emphasizing handwashing. The authors present these findings as the first report of person-to-person transmission in an outbreak of enteroinvasive E. coli.     

The role of heightened surveillance in an outbreak of Escherichia coli O157.H7.

After instituting laboratory screening for Escherichia coli O157.H7, a Connecticut hospital isolated the organism from four persons in September 1993. As a result, an outbreak of E. coli O157.H7 associated with a country club was detected. The club had served hamburger from the same shipment at two picnics. Attendees of two picnics were interviewed, stool cultures were obtained from symptomatic persons, and the remaining hamburger was cultured. Twenty (22%) of 89 persons who ate hamburger became ill, compared with 1 of 60 who did not eat hamburger (relative risk = 13.5, 95% confidence interval 3.2-56.3). Among persons who ate hamburgers, illness was strongly associated with eating hamburger that was not thoroughly cooked (P < 0.001). All 20 samples from 5 remaining boxes of patties yielded E. coli O157.H7. Isolates from hamburger and case-patients were indistinguishable by pulsed-field gel electrophoresis. Heightened surveillance can rapidly identify outbreaks and may mitigate their impact. However, continued review of food safety issues is necessary if E. coli O157.H7 outbreaks are to be prevented.     

An outbreak of Salmonella typhimurium 108/170 at a privately catered barbeque at a Sydney sports club

An outbreak of gastrointestinal illness was identified among attendees at a large community barbeque at a Sydney sports club on 30 January 2009. A retrospective cohort study was initiated, and attendees were identified through hospital emergency department gastroenteritis presentations, snowball recruitment through known cases, responders to linguistically specific press, and those returning to the venue the next week. A symptom and food history was collected from attendees, and stool samples were provided for microbiological investigation. An environmental investigation and trace back of implicated foods was also undertaken. Attendance estimates at the barbeque ranged from 100 to 180, and the food was prepared by a family that was not registered as a food business. Seventy one of the 87 attendees identified met the case definition. Thirty attendees (42%) had laboratory confirmed Salmonella Typhimurium phage-type 108/170, all with the same multilocus variable number of tandem repeat analysis typing. Burden of illness was high with 76% of cases seeking medical attention and 18% admitted to hospital. Microbiological evidence confirmed that a number of food items were contaminated with Salmonella Typhimurium 108/170, with the raw egg mayonnaise used in a Russian salad being the most likely primary food vehicle (adjusted odds ratio=10.3 [95% confidence interval 1.79-59.5]). Further, having Russian salad on the plate even if it was not consumed increased the relative risk of illness, thus suggesting that other food items may have been contaminated when they came into contact with it on the plate. This Salmonella outbreak highlighted the risks associated with the improper handling of food in private residences, which are then sold at a large public event.     

Childhood asthma in Beijing,China: a population-based case-control study

China is the most populous country in the world. Few studies, however, have been conducted there to investigate the risk factors for childhood asthma. A population-based case-control study was conducted in Shunyi County, People's Republic of China, in January 1999 and March 2001 to investigate the issue. An increased risk of childhood asthma was associated with smoking by relatives in front of the mother while she was pregnant with the child (odds ratio (OR) = 1.3, 95% confidence interval (CI): 1.0, 1.6) and with smoking by relatives in front of the child (OR = 1.4, 95% CI: 1.1, 1.9). The risk increased with the increasing number of smokers and the total minutes of smoking by relatives in front of both the child and the mother while she was pregnant with the child. An increased risk was observed for use of coal for heating (OR = 1.5, 95% CI: 1.1, 1.9). Those who reported using coal for cooking without ventilation also had an increased risk (OR = 2.3, 95% CI: 1.5, 3.5). An increased risk was observed for those who reported having molds or fungi on the ceilings of their houses (OR = 1.8, 95% CI: 1.1, 2.9) or inside the child's room (OR = 1.8, 95% CI: 1.0, 3.2). An increased risk was also found for those having both a dog and a cat as pets (OR = 1.5, 95% CI: 1.0, 2.3) or for finding both cockroaches and rats inside their houses (OR = 1.8, 95% CI: 1.2, 2.8).     

Hospital outbreak of Salmonella virchow possibly associated with a food handler

A foodborne outbreak of salmonella infection at a private hospital in London in 1994 was found to be associated with eating turkey sandwiches prepared by a food handler. One patient, nine staff, and a foodhandler's baby were confirmed to have Salmonella enterica serotype virchow, phage type 26 infection. The attack rate was estimated to be 5% among the approximately 200 patients and staff at risk. A food handler reportedly became ill days after, but her baby days before, the first hospital case. Although it appeared to be a single outbreak, antibiogram analysis, supplemented by plasmid profile typing, demonstrated that there were two strains of S. virchow involved, one with resistance to sulphonamides and trimethoprim and a second sensitive to these antimicrobial drugs. Mother and child had different strains. The investigation demonstrated the importance of full phenotypic characterization of putative outbreak strains including antimicrobial susceptibility testing.Outbreaks of foodborne infection in hospitals are preventable and are associated with high attack rates and disruption of services. There is a need for good infection control policies and training of all staff involved in patient care as well as in catering services. Consultants in Communicable Disease (CCDCs) should include private hospitals in their outbreak control plans. Good working relations between Infection Control Doctors (ICDs) in the private health sector and their local CCDCs are important if outbreaks are to be properly investigated.