Outbreak of Salmonella javiana infection at a children's hospital.

OBJECTIVE: To determine the source of an outbreak of Salmonella javiana infection. DESIGN: Case-control study. PARTICIPANTS: A total of 101 culture-confirmed cases and 540 epidemiologically linked cases were detected between May 26, 2003, and June 16, 2003, in hospital employees, patients, and visitors. Asymptomatic employees who had eaten in the hospital cafeteria between May 30 and June 4, 2003, and had had no gastroenteritis symptoms after May 1, 2003, were chosen as control subjects. SETTING: A 235-bed academic tertiary care children's hospital. RESULTS: Isolates from 100 of 101 culture-confirmed cases had identical pulsed-field gel electrophoresis patterns. A foodhandler with symptoms of gastroenteritis was the presumed index subject. In multivariate analysis, case subjects were more likely than control subjects to have consumed items from the salad bar (adjusted odds ratio [aOR], 5.3; 95% confidence interval [CI], 2.3-12.1) and to have eaten in the cafeteria on May 28 (aOR, 9.4; 95% CI, 1.8-49.5), May 30 (aOR, 3.6; 95% CI, 1.0-12.7), and/or June 3 (aOR, 4.0; 95% CI, 1.4-11.3). CONCLUSIONS: Foodhandlers who worked while they had symptoms of gastroenteritis likely contributed to the propagation of the outbreak. This large outbreak was rapidly controlled through the use of an incident command center.     

Active immunisation during an outbreak of hepatitis A in a German day-care centre

During an outbreak in a German day-care centre (DCC) caring for 100 children HAV vaccination was recommended for children, employees and household members of cases. A retrospective cohort study was done to evaluate vaccine uptake and identify possible risk factors for disease. Between 19 December 2004 and 30 January 2005 eight DCC children and seven household members fulfilled the case definition, i.e. had clinical hepatitis (14) or were diagnosed with asymptomatic HAV infection (1). Following the recommendation to vaccinate, given on 23 December 2004, 66.7% (46/69) of DCC children, 15.8% (29/184) of household members and 5/5 of employees were vaccinated, and three vaccinated children and two not vaccinated children fell ill. One of 11 children who received human normal immunoglobulin (HNIG) and four of 58 children who did not receive HNIG fell ill. In households in which the DCC child received HAV vaccine and/or HNIG, seven (5.6%) of 125 household members fulfilled the case definition. In households of non-immunised children none of the 59 household members fell ill. We conclude that, although most vaccinations were administered promptly, they may not have been timely enough to impact the course of the outbreak.     

介毛蚶传播甲型肝炎爆发流行调查报告

1988年1月20日至4月30日宁波市发生病毒性肝炎爆发,报告病例47 313例,死亡4例,发病率为949.78/10万,病死率为0.03‰;病人血清抗-HAV IgM阳性率为95.55%;82.56%的病例有食蚶史;流行病学调查表明食蚶居民发病率(8.53%)与未食蚶居民发病率(0.77%)有极显著性差异(χ²=39.49,P<0.01、RR=11.08),食蚶的归因危险性百分比(AR%)为90.97%。病原学检测(用细胞培养法和核酸杂交试验)证实经在本市海涂放养59天后的启东毛蚶 其体内仍携带HAV。因此,认为启东毛蚶是本次甲型肝炎爆发的传播媒介。     

A common-source outbreak of trichinosis from consumption of bear meat

This paper discusses an outbreak of trichinosis that occurred in 1998 in Montgomery County, Ohio, and the investigation that followed. The outbreak was associated with consumption of bear meat from a hunt in Ontario, Canada. The person who had the index case had eaten two bear burgers that were cooked rare in a microwave oven. Bear meat from the same hunt later was consumed by 15 other people at a church supper and an additional 13 people who did not attend the supper. Of the 15 attendees at the church supper who ate the bear meat, seven developed illness consistent with Trichinella infection (attack rate about 47 percent). An additional seven people attended the supper but did not eat the bear meat and did not become ill. Having eaten bear meat at the church supper was associated with an increased risk of illness (p = .05). Inadequate cooking of the bear meat resulted in the transmission of live trichinae. The 13 other people who ate the bear meat but did not attend the supper reported no illness. A total of eight people, including the person with the index case, met the case definition for trichinosis. Adequate cooking of the bear meat or consumption of uninfected portions of the meat was probably the protective factor for those who did not become ill after consuming the bear meat.     

A large Clostridium perfringens foodborne outbreak with an unusual attack rate pattern

On November 7, 1985, a Clostridium perfringens gastroenteritis outbreak occurred in approximately 44% of the 1,362 employees at a Connecticut factory. Although the same foods were served to all three shifts at an employee banquet on November 6, the attack rate was almost twice as high for those who ate on the day shift (attack rate = 50%) than for those on the evening shift (attack rate = 20%) or night shift (attack rate = 29%). Among employees of the day shift, attack rates were highest for those who ate during the first 30 minutes of the 2.5-hour day shift serving period and decreased throughout the serving period. The one-hour evening shift serving period had a similar trend toward higher attack rates earlier in the serving period. Four main-course foods were significantly associated with illness, and over 95% of the employees had eaten each of them. Stratified analysis indicated that gravy was the responsible food and, furthermore, that the decreasing attack rate pattern within serving periods occurred only for those who ate gravy. The gravy had been prepared 12-24 hours in advance of banquet service. After it was prepared, the gravy was improperly cooled and was reheated shortly before and throughout the serving periods. Persons who ate gravy that had been reheated for the longest period of time had the lowest attack rate, probably because they were exposed to a lower concentration of organisms. This outbreak underscores the need for properly reheating food to prevent C. perfringens gastroenteritis and suggests that analysis of attack rate trends may provide important epidemiologic clues to understanding the causes of foodborne disease outbreaks.     

An outbreak of Salmonella hadar associated with food consumption at a building site canteen

A biphasic outbreak of gastroenteritis caused by Salmonella hadar affected canteen employees and workers at a construction site in central Italy in September 1994. There were 448 symptomatic cases, from 61 of whom group C Salmonella was isolated. Six cases were canteen employees. Twenty-two other individuals were asymptomatic excreters. There were 10 secondary cases. Working as a food handler at the canteen constituted an increased risk of infection, independently of ingestion of the food (odds ratio: 62.1; 95% confidence interval (CI): 9.5– 406.6). Having eaten at the canteen on the 19th and 20th September was identified as risk factor for subjects symptomatic within 72 hours (relative risk (RR): 17.0, 95% CI: 2.3–124.3), and cooled meat salad was identified as the vehicle of infection (RR: 36.6, 95% CI: 14.3–93.8). The use of portable toilets was another possible route of transmission of infection for all cases (RR: 1.3, 95% CI: 1.0–1.6). The index case was a cook who had symptoms five days before the peak of the outbreak. From 27 individuals both symptomatic and asymptomatic excreters group B, group D and not-typed Salmonellas were isolated. This study underlines the problem of improper food handling in salmonellosis outbreaks and emphasizes the role of several vehicles in the transmission of salmonellosis in a community.     

Epidemiological analysis of a cluster within the outbreak of Shiga toxin-producing Escherichia coli serotype O104:H4 in Northern Germany, 2011

In May 2011 one of the worldwide largest outbreaks of haemolytic uraemic syndrome (HUS) and bloody diarrhoea caused by Shiga toxin-producing Escherichia coli (STEC) serotype O104:H4 occurred in Germany. One of the most affected federal states was Lower Saxony. We present the investigation of a cluster of STEC and HUS cases within this outbreak by means of a retrospective cohort study. After a 70th birthday celebration which took place on 7th of May 2011 among 72 attendants seven confirmed cases and four probable cases were identified, two of them developed HUS. Median incubation period was 10 days. Only 35 persons (48.6%) definitely answered the question whether they had eaten the sprouts that were used for garnishing the salad. Univariable analysis revealed different food items, depending on the case definition, with Odds Ratio (OR) > 1 indicating an association with STEC infection, but multivariable logistic regression showed no increased risk for STEC infection for any food item and any case definition. Sprouts as the source for the infection had to be assumed based on the results of a tracing back of the delivery ways from the catering company to the sprouts producer who was finally identified as the source of the entire German outbreak. In this large outbreak several case–control studies failed to identify the source of infection.     

Measles immunity among community hospital employees.

OBJECTIVE: To define measles immunity rates among employees at 2 hospitals during a community outbreak in 1990. DESIGN: Cohort survey using enzyme-linked immunosorbent assay (ELISA) and questionnaire. SETTING: Two community hospitals. PARTICIPANTS: Seventy-six percent of 2,060 employees. RESULTS: Seven percent (115/1566) of participants lacked ELISA-defined measles immunity. Among employees whose ages were known, 14% (64/467) of those born after 1956 and 5% (50/1086) of those born before 1957 lacked serologic evidence of immunity. Fifty-eight percent of the susceptible persons had substantial patient contact. With ELISA results as the reference for immunity, the predictive value of an undocumented positive history of measles disease or vaccination was 95%; the predictive value of a negative history of both was 52%. Measles developed in 7 employees. CONCLUSIONS: A substantial number of hospital employees lacked ELISA-defined measles immunity, including many who had patient contact or who had been born before 1957. Undocumented disease and vaccination histories were not adequate predictors of serologic status. This study supports the recommendations and suggestions of the Immunization Practices Advisory Committee that hospitals should require documented evidence of measles immunity from employees who have patient contact.     

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.     

A prolonged outbreak of Norwalk-like calicivirus (NLV) gastroenteritis in a rehabilitation centre due to environmental contamination

An outbreak of Norwalk-like calicivirus (NLV) gastroenteritis occurred in a rehabilitation centre in southern Finland between December 1999 and February 2000. An epidemiological investigation was conducted to determine the source and extent of the outbreak. More than 300 guests and staff members became ill during the outbreak. No food or activity in the centre could be linked epidemiologically to illness. NLV genogroup II was detected by RT-PCR in stool samples of symptomatic guests and employees. All strains reacted similarly with the microplate hybridization probe panel and showed the same nucleotide sequence, indicating that they represented the same NLV strain. Food and water samples were negative for NLV, whereas NLV was detected in three environmental specimens. The strains from patients and environment were identical based on microplate hybridization probes, suggesting that environmental contamination may have been important for the spread of calicivirus and the protracted course of the outbreak.     

一起医院住院病人诺如病毒急性胃肠炎暴发疫情的 调查

摘要:目的　调查某医院住院病人腹泻暴发疫情的致病因子,找出传染源和危险因素,提出针对性的预防控制建议,有效控制疫情。方法　采用统一的调查表对病例进行流行病学调查;开展现场卫生学调查并采集便标本,采用RT-PCR对便标本进行诺如病毒核酸检测。结果　调查该病区暴露的住院患者和医务人员135名,发现22名病例,罹患率为16.30%;患者临床表现以腹泻、恶心、呕吐为主,部分患者出现发热症状;不同楼层住院老人罹患率差异无统计学意义（χ2＝0.82,P＞0.05）;住院老人罹患率高于护工（χ2＝5.35,P＜0.05）,不同性别住院老人发病风险相同（χ2＝0.18,P＞0.05）;采集的14份便标本中,8份检测结果为诺如病毒核酸阳性。结论　该次急性胃肠炎暴发疫情是由诺如病毒引起,传染源可能为隐形感染者或病原携带者,病毒通过某种共用媒介传播后再以人-人传播模式进一步扩散,高危人群为住院老人;采取针对性措施后,疫情得以有效控制。     

An outbreak of gastrointestinal illness associated with the consumption of escolar fish.

An outbreak of gastrointestinal illness occurred amongst attendees of a conference lunch in the Hunter area, New South Wales, in October 2001. A distinctive symptom reported by many ill persons was the presence of oily diarrhoea. The Hunter Public Health Unit investigated the outbreak by conducting a telephone interview of the cohort of conference attendees using a standard questionnaire. Twenty persons out of 44 attendees (46%) became ill following the conference. The median incubation period was 2.5 hours (range 1-90 hours). The most common symptoms reported were; diarrhoea (80%)-38 per cent of these reported oily diarrhoea; abdominal cramps (50%); nausea (45%); headache (35%) and vomiting (25%). For analyses, a case was defined as a person who developed oily diarrhea, or diarrhoea within 48 hours, or had at least two other symptoms of gastroenteritis within 6 hours, of the conference lunch. Seventeen persons had symptoms that met the case definition. None of the foods or beverages consumed were significantly associated with illness, however, all cases had consumed fish and none of those who did not eat fish (4 persons) became ill. Moreover, only 'fish' or 'potato chips' could explain a significant proportion of the illness. Analysis of the oil composition of the fish consumed was consistent with the known profile of the species marketed as 'escolar'. Among those who consumed fish the following potential risk factors did not have a significant association with the illness; Body Mass Index, age, health status and the amount of fish consumed. We concluded that consumption of fish within the marketing group escolar can cause severe abdominal cramping, nausea and vomiting, in addition to incontinent diarrhoea.     

An evaluation of the risk assessment method used by Environmental Health Officers when inspecting food businesses

Two outbreaks of infection with Salmonella enteritidis phage types 5c and 6a occurred in a number of Scottish health board areas between May 2000 and January 2001. A case-control study of food businesses was subsequently carried out to ascertain whether the scores derived from Environmental Health Officers' inspections prior to the outbreaks differed between food businesses where outbreak cases had eaten in the week before the onset of their illness (case food businesses) and neighbouring food businesses at which no outbreak case had eaten (control food businesses). The study showed no significant difference between the scores of case and control food businesses. The results suggest that the inspections were ineffective in identifying those food businesses that are more likely to cause incidents of food poisoning.     

Outbreak of Pseudomonas aeruginosa ventriculitis among patients in a neurosurgical intensive care unit.

OBJECTIVE: To determine the cause of an outbreak of Pseudomonas aeruginosa cerebral ventriculitis among eight patients at a community hospital neurosurgical intensive care unit. All had percutaneous external ventricular catheters (EVCs) to monitor cerebrospinal fluid (CSF) pressure. METHODS: Cohort study of all patients who had EVCs placed during the epidemic period (August 8-October 22, 1997). A case-patient was any patient with P aeruginosa ventriculitis during the epidemic period. Pulsed-field gel electrophoresis (PFGE) was performed on all isolates. RESULTS: P aeruginosa was significantly more likely to be isolated from CSF per EVC placed in the epidemic than pre-epidemic (January 1-August 7, 1997) periods (8/61 [13%] vs 2/131 [1.5%], P=.002). During the epidemic period, ventriculitis was significantly more likely after EVC placement in the operating room than in other units (8/24 vs 0/22, P=.004). EVC placement technique differed for EVCs placed in the operating room (little hair was removed, preventing application of an occlusive dressing) versus other hospital units (more hair was removed, and an occlusive dressing was applied). Among patients who had operating room EVC placement, contact with one healthcare worker was statistically significant (7/13 vs 0/8, P=.02). Hand cultures of this worker were negative. All isolates had closely related PFGE patterns. CONCLUSIONS: These data suggest that a single healthcare worker may have contaminated EVC insertion sites, resulting in an outbreak of P aeruginosa ventriculitis. Affected patients were unlikely to have had an occlusive dressing at the EVC insertion site. Application of a sterile occlusive dressing may decrease the risk of ventriculitis in patients with EVCs.     

深圳市某塑胶工厂一起由植物皂素导致的食物中毒事件调查

目的 调查分析一起某塑胶工厂食堂发生的植物皂素中毒事件的原因和特点,为皂素中毒事件预防控制提供参考。 方法 使用食物中毒个案调查表收集深圳市某塑胶工厂中毒患者资料,通过现场调查和电话访问等方法收集本次中毒事件相关信息,通过回顾性队列研究分析事件发生的可疑餐次和可疑食品。 结果 此次皂素中毒事件共发现患者8例,员工罹患率为28.57％(8/28)。患者临床症状以头晕(100%)、呕吐(87.50%)为主。员工食用4月10日公司食堂提供的中餐者罹患率(50.00%)显著高于未食用当日中餐者(0%)(P=0.008, RR=+∞),当日中餐食用薯蓣骨头汤者罹患率(100%)高于未食用者(0%)(P<0.001)。检测患者呕吐物、剩余食品(薯蓣)样品和食品原材料(生薯蓣)皂素毒素阳性。 结论 该事件为一起皂素毒素中毒事件,致病因子为4月10日中餐未煮熟的薯蓣骨头汤。薯蓣属食物含有植物皂素,食用时需煮熟煮透避免引起中毒。     

Tightly clustered outbreak of group A streptococcal disease at a long-term care facility.

OBJECTIVE: To describe investigation of a tightly clustered outbreak of invasive group A streptococcal (GAS) disease associated with a high mortality rate in a long-term care facility (LTCF). DESIGN: Cross-sectional carriage survey and epidemiologic investigation of LTCF resident and employee cohorts. SETTING: A 104-bed community LTCF between March 1 and April 7, 2004. PATIENTS: A cohort of LTCF residents with assigned beds at the time of the outbreak. INTERVENTIONS: Reinforcement of standard infection control measures and receipt of chemoprophylaxis by GAS carriers. RESULTS: Four confirmed and 2 probable GAS cases occurred between March 16 and April 1, 2004. Four case patients died. The final case occurred during the investigation, before the patient was determined to be a GAS carrier. No case occurred during the 6 months after the intervention. Disease was caused by type emm3 GAS; 16.5% of residents and 2.4% of employees carried the outbreak strain. Disease was clustered in 1 quadrant of the LTCF and associated with nonintact skin. GAS disease or carriage was associated with having frequent personal visitors. CONCLUSIONS: Widespread carriage of a virulent GAS strain likely resulted from inadequate infection control measures. Enhanced infection control and targeted prophylaxis for GAS carriers appeared to end the outbreak. In addition to employees, regular visitors to LTCFs should be trained in hand hygiene and infection control because of the potential for extended relationships over time, leading to interaction with multiple residents, and disease transmission in such residential settings. Specific attention to prevention of skin breaks and proper wound care may prevent disease. The occurrence of a sixth case during the investigation suggests urgency in addressing severe, large, or tightly clustered outbreaks of GAS infection in LTCFs.     

A regional Salmonella enterica serovar Typhimurium outbreak associated with raw beef products, The Netherlands, 2010

Between April and May 2010, several medical microbiological laboratories in the Netherlands notified a total of 90 cases of Salmonella enterica serovar Typhimurium with the same antibiogram type (resistant for ampicillin, tetracycline, and co-trimoxazol) and the same multiple locus variable number tandem repeats analysis pattern (03-16-09-NA-311) or single locus variants. Date of illness onset ranged from end of March to mid-May with a peak in the second week of April. Almost half of the cases were hospitalized. Cases completed a questionnaire about food items and other risk factors in the 7 days before illness onset. A matched case-control study was performed. Consumption of "ossenworst" (matched odds ratio 48.2 [95% confidence interval (CI): 3.9-595.9]) and filet américain (8.5 [95% CI: 1.0-73.6]) were found to be significant risk factors for illness. Eighty percent of the cases had eaten at least one or both raw meat products. The producer of the ground beef that was used to produce the "ossenworst" was identified, but no microbiological evidence was found. Consumers should be made more aware of the presence of raw meat in ready-to-eat products and of the potential risk in eating these products. Vulnerable persons such as young children, elderly, and persons with poor health should be discouraged from eating these products. Detection of this outbreak was mainly based on the antibiogram pattern that had identified possible cases 10 days before detailed typing results from the reference laboratory became available, thus facilitating early case findings.     

An outbreak of watermelon-borne pesticide toxicity.

The largest reported United States outbreak of illness caused by a foodborne pesticide was due to aldicarb-contaminated watermelons. In Oregon, where the first episodes of toxicity were reported, 264 reports were received, and 61 definite cases were identified. Residues of aldicarb, a cholinesterase inhibitor, were found in 10 of 16 tested melons which had been eaten by persons meeting the case definition. The outbreak demonstrates the need for enhanced physician vigilance with respect to anticholinesterase intoxication. It also demonstrates the value of an established system for reporting of unusual illness to public health officials.     

Azithromycin prophylaxis during a hospitalwide outbreak of a pertussis-like illness.

A questionnaire regarding tolerability and adherence was administered for 5 days to hospital employees who received azithromycin prophylaxis during a hospitalwide outbreak of a pertussis-like illness. Analysis of the 239 responses from those having received prophylactic azithromycin determined that it was well tolerated and accounted for a minimal loss of days worked; 81.5% were fully adherent with the regimen.