An outbreak of gastroenteritis caused by both rotavirus and Shigella sonnei in a private school in Rio de Janeiro

In May 1980 an extensive outbreak of gastroenteritis occurred in a private school in the city of Rio de Janeiro. Examination of faeces and paired sera showed that this outbreak was caused by both rotavirus and a virulent strain of Shigella sonnei. In the first 19 stool samples collected seven (37%) had rotavirus only, six (32%) had Sh. sonnei only, while four (21%) had both agents. Examination of the second and third stool collections revealed only the presence of Sh. sonnei. The 18 paired sera showed seroconversion for rotavirus in four cases (22%) and in seven cases (39%) for Sh. sonnei. The overall attack rate of the disease was approximately 75%, the nursery and kindergarten having higher attack rates. Students in all grades became sick at the same time, and the unimodal curve of the onset dates of symptoms indicates a common source outbreak. Evidence suggested a contaminated water supply.     

An outbreak of gastroenteritis caused by both rotavirus and Shigella sonnei in a private school in Rio de Janeiro.

In May 1980 an extensive outbreak of gastroenteritis occurred in a private school in the city of Rio de Janeiro. Examination of faeces and paired sera showed that this outbreak was caused by both rotavirus and a virulent strain of Shigella sonnei. In the first 19 stool samples collected seven (37%) had rotavirus only, six (32%) had Sh. sonnei only, while four (21%) had both agents. Examination of the second and third stool collections revealed only the presence of Sh. sonnei. The 18 paired sera showed seroconversion for rotavirus in four cases (22%) and in seven cases (39%) for Sh. sonnei. The overall attack rate of the disease was approximately 75%, the nursery and kindergarten having higher attack rates. Students in all grades became sick at the same time, and the unimodal curve of the onset dates of symptoms indicates a common source outbreak. Evidence suggested a contaminated water supply.     

A large outbreak of Shigella sonnei gastroenteritis associated with consumption of fresh pasteurised milk cheese

A large outbreak of Shigella sonnei gastroenteritis occurred in Murcia Region (Southeast Spain) in the winter of 1995–1996. More than 200 people were affected. Epidemiological investigations implicated a regionally manufactured fresh pasteurised milk cheese as the vehicle of infection. A case–control study showed a statistically significant association between the illness and consumption of the suspect cheese. The dispersed sale of the cheese resulted in a regional dissemination of the organism and people were affected in eight townships. Research suggested that an infected foodhandler at the cheese factory might have been the source of contamination and that the processing method might have allowed cross-contamination to occur. This study emphasises the importance of increasing the control of strict hygiene during the processing of fresh cheese, since legislation does not forbid direct contact by hand that could result in contamination of cheese even when the milk pasteurisation process was correctly performed.     

International foodborne outbreak of Shigella sonnei infection in airline passengers

During 22-24 August 2004, an outbreak of Shigella sonnei infection affected air travellers who departed from Hawaii. Forty-seven passengers with culture-confirmed shigellosis and 116 probable cases who travelled on 12 flights dispersed to Japan, Australia, 22 US states, and American Samoa. All flights were served by one caterer. Pulsed-field gel electrophoresis of all 29 S. sonnei isolates yielded patterns that matched within one band. Food histories and menu reviews identified raw carrot served onboard as the likely vehicle of infection. Attack rates for diarrhoea on three surveyed flights with confirmed cases were 54% (110/204), 32% (20/63), and 12% (8/67). A total of 2700 meals were served on flights with confirmed cases; using attack rates observed on surveyed flights, we estimated that 300-1500 passengers were infected. This outbreak illustrates the risk of rapid, global spread of illness from a point-source at a major airline hub.     

A community waterborne outbreak of gastro-enteritis attributed to Shigella sonnei

An outbreak of gastro-enteritis occurred in a community of 2213 persons located near the city of Ioannina, in North-western Greece. Two hundreds and eighty-eight inhabitants of the village of Eleoussa, suffered from gastro-enteritis between 11 and 22 October. The peak of the epidemic occurred during the first 3 days (11-13 October). The highest risk of developing gastro-enteritis was observed in the age group 0-14 years (41.4%) and decreased significantly with age (P < 0.01). Patients over 65 years were more frequently hospitalized than those in other age groups (P < 0.05). Shigella sonnei was isolated from both, water samples and faeces of patients. Control measures were implemented on the second day of the outbreak. Environmental conditions suggest that contaminationof the water system occurred by groundwater.     

An outbreak of diarrhoeal disease attributed to Shigella sonnei.

An outbreak of gastroenteritis occurred in a village on the Island of Crete, with 1479 inhabitants. One hundred and thirty-eight symptomatic patients from 57 different families were examined. Thirty percent of children under 12 years were affected compared with 4% of adolescents and adults (P < 0.0001). Thirty-five out of 105 stool cultures (33%) grew Shigella sonnei. Thirty-four isolates had the same susceptibility pattern and were sensitive to ampicillin, while one was resistant to this antibiotic. Thirty-three isolates had the same plasmid profile. Based on epidemiologic and environmental findings, it was concluded that the transmission of shigellosis was waterborne. Shigella were not isolated from water, but one of the three village springs was found to be contaminated with faecal coliforms. This spring was probably contaminated by sewage material, due to its proximity to a source of untreated sewage effluent. Implementation of environmental and control measures brought the epidemic to an end.     

Waterborne outbreak of gastroenteritis in a religious summer camp in Norway, 2002

In July 2002 an outbreak of acute gastroenteritis occurred in a camp facility in western Norway during a 10-day seminar, with around 300 guests staying overnight and several day-time visitors. Environmental and epidemiological investigations were conducted to identify and eliminate the source of the outbreak, prevent further transmission and describe the impact of the outbreak. Of 205 respondents, 134 reported illness (attack rate, 65%). Multivariate analysis showed drinking water and taking showers at the camp-site to be significant risk factors. Secondary person-to-person spread among visitors or outside of the camp was found. Norovirus was identified in 8 out of the 10 stool samples analysed. Indicators of faecal contamination were found in samples from the private untreated water supply, but norovirus could not be identified. This outbreak investigation illustrates the importance of norovirus as a cause of waterborne illness and the additional exacerbation through person-to-person transmission in closed settings. Since aerosol transmission through showering contributed to the spread, intensified hygienic procedures such as isolation of cases and boiling of water may not be sufficient to terminate outbreaks with norovirus.     

Waterborne outbreak of Norwalk-like virus gastroenteritis at a tourist resort,Italy

In July 2000, an outbreak of gastroenteritis occurred at a tourist resort in the Gulf of Taranto in southern Italy. Illness in 344 people, 69 of whom were staff members, met the case definition. Norwalk-like virus (NLV) was found in 22 of 28 stool specimens tested. The source of illness was likely contaminated drinking water, as environmental inspection identified a breakdown in the resort water system and tap water samples were contaminated with fecal bacteria. Attack rates were increased (51.4%) in staff members involved in water sports. Relative risks were significant only for exposure to beach showers and consuming drinks with ice. Although Italy has no surveillance system for nonbacterial gastroenteritis, no outbreak caused by NLV has been described previously in the country.     

An outbreak of multi-resistant Shigella sonnei in a long-stay geriatric nursing centre

An outbreak of Shigella sonnei infection in a long-stay nursing centre was detected during routine surveillance of notifications in July 1999. Subsequent investigations identified 13 cases of multi-resistant S. sonnei infection affecting nine staff, three community members associated with the centre and one resident of the centre. Each isolate of S. sonnei was genetically indistinguishable. The outbreak investigation identified contact with residents with vomiting and diarrhoea as a significant risk factor for infection amongst staff providing nursing care. This association, and the duration of the outbreak over several months, suggests that transmission was most likely person-to-person. This outbreak demonstrates the importance of infection control policies and hygiene measures in long-stay nursing facilities.     

Epidemiologic study of an outbreak of clenbuterol poisoning in Catalonia,Spain.

In an investigation of 113 cases of clenbuterol poisoning in Catalonia, Spain, in 1992, more than 50 percent of those affected were found to have had symptoms of nervousness, tachycardia, muscle tremors, myalgia, and headache. There was no significant difference in the distribution of symptoms according to sex (P = 0.97). The period of incubation varied between 15 minutes and 6 hours and the duration of symptoms between 90 minutes and 6 days. Clenbuterol was detected in 47 urine samples in amounts ranging from 11 to 486 parts per billion. No traces of clenbuterol were found in serum samples. Intoxication occurred in association with the ingestion of veal liver, irrespective of the way in which the liver had been cooked. The association between consuming liver and falling ill was statistically significant (P < 0.0001). In one family, the suspected source of intoxication was meat (veal tongue) and in another canneloni. None of the patients died as a result of the intoxication. The findings reinforce the need to uphold the prohibition of the use of clenbuterol in cattle farming in those countries and communities where it already exists and to contemplate a stricter regulation of its therapeutic use.     

Waterborne outbreak of gastroenteritis transmitted through the public water supply

INTRODUCTION: The chlorination of public water supplies has led researchers to largely discard drinking water as a potential source of gastroenteritis outbreaks. The aim of this study was to investigate an outbreak of waterborne disease associated with drinking water from public supplies. METHODS: A historical cohort study was carried out following notification of a gastroenteritis outbreak in Baqueira (Valle de Arán, Spain). We used systematic sampling to select 87 individuals staying at hotels and 67 staying in apartments in the target area.Information was gathered on four factors (consumption of water from the public water supply, sandwiches, water and food in the ski resorts) as well as on symptoms. We assessed residual chlorine in drinking water, analyzed samples of drinking water, and studied stool cultures from 4 patients. The risk associated with each water source and food type was assessed by means of relative risk (RR) and 95% confidence intervals (CI). RESULTS: The overall attack rate was 51.0% (76/149). The main symptoms were diarrhea 87.5%, abdominal pain 80.0%, nausea 50.7%, vomiting 30.3%, and fever 27.0%. The only factor associated with a statistically significant risk of disease was consumption of drinking water (RR = 11.0; 95% CI, 1.6-74.7). No residual chlorine was detected in the drinking water, which was judged acceptable. A problem associated with the location of the chlorinator was observed and corrected. We also recommended an increase in chlorine levels, which was followed by a reduction in the number of cases. The results of stool cultures of the four patients were negative for enterobacteria. CONCLUSIONS: This study highlights the potential importance of waterborne outbreaks of gastroenteritis transmitted through drinking water considered acceptable and suggests the need to improve microbiological research into these outbreaks (viruses and protozoa detection).     

A study of whooping cough epidemic outbreak in Castellon,Spain

BACKGROUND: Based on the report of several cases at one school, a study of an epidemic outbreak was started for the purpose of characterizing this outbreak from the person, place and time standpoint, calculating the effectiveness of the immunization and the concordance of the cases with the positive result of the serological study. METHODS: A "case" is defined as being that individual who has a cough fasting for two weeks. A study is made of the spread of the disease by means of the epidemic curve and the effectiveness of the pertussis vaccine. The concordance of the cases and the positive serology is evaluated by way of the Kappa index. RESULTS: From among the students at several schools and those with whom they were living at the time, a total of 130 individuals were surveyed, 94 of whom fit the "case" definition. The average age of the cases was 10.5 years of age, 42.6% being males and 84% school age children, 71.3% showing signs of recent infection (positive IgM), the average length of time since the last whooping cough immunization being 8.25 years. The effectiveness of the whooping cough booster is 66%. The concordance between the cases and the positive results of the serology reveals a Kappa = 0.45. No B. Pertussis was isolated in the 25 throat swab samples. CONCLUSIONS: Classrooms and the family environment are a factor in spreading this disease. The including of a booster at 18 months improves the effectiveness of the whooping cough immunization. The isolation of B. Pertussis is not very frequent, and the serology may be an alternative when this disease is clinically suspected.     

Outbreaks of multidrug-resistant Shigella sonnei gastroenteritis associated with day care centers--Kansas, Kentucky, and Missouri, 2005

Infection with Shigella sonnei that is resistant to antibiotics commonly used in pediatric practice has become more common during the past decade. In 2005, Kansas, Kentucky, and Missouri reported increases in shigellosis cases associated with day care centers caused predominantly by multidrug-resistant (MDR) (i.e., resistant to ampicillin and trimethoprim-sulfamethoxazole [TMP/SMX]) strains of S. sonnei. Pulsed-field gel electrophoresis (PFGE) patterns for isolates from Kansas and Missouri were similar, suggesting a common outbreak in the Kansas City area, whereas isolates from Kentucky had a different pattern. This report describes the investigation of two outbreaks of MDR shigellosis associated with day care centers and reviews measures for prevention and control of S. sonnei infection in these settings. Given the current rates of resistance to antibiotics available to treat children with shigellosis safely, public health measures initiated during shigellosis outbreaks should focus on promoting appropriate handwashing and diapering practices in day care centers.     

Plasmid typing of Shigella sonnei epidemic strains and molecular relationship of their R-plasmids

We conducted a surveillance program on epidemic and/or endemic Shigella strains in Asturias (Spain), their frequency and dispersion in our community, and their R-plasmids. We analyzed initial isolates of Shigella sonnei from two epidemic outbreaks using antibiotic resistance patterns and plasmid profile analysis as epidemiological markers. We found that the 2 outbreaks were caused by different S. sonnei strains, which respectively carried one and two R-plasmids together with other plasmids. The molecular relationship among these and three other R-plasmids from two S. sonnei strains isolated during a previous outbreak, were studied by restriction enzyme analysis and DNA-DNA hybridizations. We were able to establish different levels of relationship among the six R-plasmids.Corresponding author.