A Waterborne Gastroenteritis Outbreak Caused by a GII Norovirus in a Holiday Camp in Catalonia (Spain), 2017

On 2 February 2017, Epidemiological Surveillance Services were notified of an outbreak of acute gastroenteritis (AGE) among schoolchildren who had taken part of a school trip from 30 January to 3 February 2017 at a holiday camp in Catalonia. A retrospective cohort study was performed to identify the causative agent, estimate the magnitude of the outbreak and identify its source, as well as to determine the route of transmission. Data collected by standardised questionnaires identified 41 episodes of AGE among 174 individuals who attended the camp. Cases had mainly symptoms of abdominal pain (73.8%), nausea (64.3%), vomiting (54.8%), diarrhoea (45.2%) and headache (42.9%). Consumption of water was associated with gastroenteritis (crude RR: 1.72, 95%CI: 1.01–2.92; adjusted RR: 1.88, 95%CI 1.03–3.56). NoV GII was detected in faeces (5 out of 13) and water samples. Additionally, faecal indicator bacteria and protozoa were detected in water samples. The outbreak showed a high attack rate and was caused by a natural water fountain not properly treated and not monitored for safety quality. There could have been a discharge of wastewater at a point close to the fountain; however, the source of contamination of the water could not be identified. Health education may be useful to eliminate risks associated with the consumption of untreated water from natural fountains.     

Two sequential outbreaks of rotavirus gastroenteritis: evidence for symptomatic and asymptomatic reinfections

In two sequential outbreaks of rotavirus gastroenteritis that occurred in a kibbutz in southern Israel (the Negev), 32 persons (9% of the population) were ill in the first and 45 (13% of the population) in the second. Excretion of virus, changes in titers of rotavirus-specific serum IgG, or both implicated rotavirus in 72% of the illnesses in outbreak 1 and in 56% of the illnesses in outbreak 2. In both outbreaks the age-specific morbidity rate decreased with increasing age. Half (six of 12) of the children six to 27 months of age who were ill with rotavirus in outbreak 1 were ill with rotavirus again in outbreak 2, whereas two were asymptomatically infected; older children who were ill in outbreak 1 were not ill in outbreak 2. Serotype determination by enzyme-linked immunosorbent assay using monoclonal antibodies to VP7 implicated a serotype 3 virus in outbreak 1 and a serotype 1 virus in outbreak 2.     

Food-borne outbreak of gastroenteritis caused by small round structured virus. 2. An outbreak associated with bakery product consumption]

In December 1989, an outbreak of gastroenteritis associated with cake consumption occurred in a day-care center with 60 children and 12 staff in Saitama prefecture. Children were served cakes at the Christmas party held in the day-care center and ate them with their families. Thirty-three of the 59 children (56%), 16 of the 74 families (22%) and 1 of the 10 staff (10%) eating the cakes became ill. Illness consisted primarily of nausea, vomiting, diarrhea and fever; the median incubation period was 31 hours. Bacteriological analysis of stool specimens did not reveal a causative agent. Small round structured viruses (SRSV) were detected in fecal specimens from 10 of the 17 ill children (59%) and 2 of the 6 ill families (33%) by electron microscopy. Cakes were purchased from a bakery where an employee who prepared the cake denied symptoms, and SRSV was not detected in the fecal specimen from the employee. Thus, it was not determined that the cake was contaminated by a food handler.     

A large nontypical outbreak of Norwalk virus. Gastroenteritis associated with exposing celery to nonpotable water and with Citrobacter freundii.

The US Air Force Academy experienced a point-source outbreak of gastroenteritis originally believed to be caused by Salmonella. The overall attack rate was 48% among approximately 3000 cadets and staff. Food-specific attack rates implicated chicken salad. The odds ratio for chicken salad consumption in ill cadets was 10.7 (95% confidence interval: 8.2; 13.8). The celery component had been exposed to nonpotable water. Citrobacter freundii were statistically associated with consumption of the suspected vehicle and subsequent illness. Most aspects were consistent with the epidemiology of Norwalk gastroenteritis. However, the clinical presentation was not typical of reported outbreaks. One hundred five cadets required intravenous rehydration. Serum samples implicated Norwalk virus as the most probable cause of this outbreak. The Centers for Disease Control (Atlanta, Ga) recently began national surveillance for viral gastroenteritis. All outbreaks of gastroenteritis associated with nonpotable water should be investigated for evidence of viral cause.     

Incidence and epidemiology of irritable bowel syndrome after a large waterborne outbreak of bacterial dysentery

BACKGROUND & AIMS: Postinfectious irritable bowel syndrome (PI-IBS) is a common clinical phenomenon. To better define its incidence and epidemiology, a large cohort study was initiated after the contamination of a municipal water supply led to a large outbreak of acute Escherichia coli 0157:H7 and Campylobacter jejuni gastroenteritis. METHODS: Local residents were invited to undergo structured assessments at research clinics established 2 years after the outbreak. Permanent adult residents with no prior history of inflammatory bowel disease or IBS were eligible. Standardized questionnaires defined past and current health. The cohort was divided into controls without gastroenteritis, subjects with clinically suspected gastroenteritis, and subjects with only self-reported gastroenteritis that could not be substantiated by another source. A modified Bowel Disease Questionnaire identified IBS according to Rome criteria. The incidence and epidemiology of PI-IBS was characterized. Risk factors were assessed using multiple logistic regression. RESULTS: There were 2069 eligible study participants. Rome I criteria were met by 71 of 701 controls (10.1%) vs 249 of 904 subjects with self-reported gastroenteritis (27.5%) and 168 of 464 subjects with clinically suspected gastroenteritis (36.2%) (all comparisons, P < 001). Independent risk factors for PI-IBS included younger age, female sex, bloody stools, abdominal cramps, weight loss, and prolonged diarrhea. PI-IBS was more likely than sporadic IBS to show diarrhea-predominant features. CONCLUSIONS: PI-IBS is common after gastroenteritis from water contamination and often is diarrhea-predominant. Characteristics of the acute illness identify patients at increased risk for PI-IBS.     

Cryptosporidium parvum-specific antibody responses among children residing in Milwaukee during the 1993 waterborne outbreak

A major gastroenteritis outbreak among >400,000 residents of Milwaukee, Wisconsin, in April 1993 was attributed to Cryptosporidium parvum oocysts in drinking water. Plasma specimens obtained from children (6 months to 12 years old) for routine blood lead level surveillance March-May 1993 were assayed by ELISA for levels of IgG antibody against the immunodominant Triton-17 and 27-kDa C. parvum antigens. Over a 5-week period, the seroprevalence for antibodies to the 2 antigens increased from 15% to 82% and from 17% to 87%, respectively, in samples from children living in southern ZIP code areas (n=218), whereas smaller increases (20% to 43% and 22% to 46%, respectively) were noted among samples from children living in northern ZIP code areas (n=335; P<.0001). The results demonstrate that C. parvum infection was much more widespread than previously appreciated and confirm that infection was associated with residence in the area served by the southern water treatment plant.     

Serological responses among teenagers after natural exposure to Norwalk virus

Twenty-one teenagers exposed to a contaminated water supply during an outbreak of gastroenteritis were tested for seroconversion to Norwalk virus. Serum specimens were collected within 72 hr of exposure and four weeks later. Each of the 11 individuals who developed symptoms and five of the 10 who remained well had a whole-antibody response in serum. None of the remaining five teenagers became ill or seroconverted. Neither seroconversion nor susceptibility to illness was associated with an absence of detectable antibody from acute-phase serum specimens. These findings support the view that immunity to Norwalk virus is not determined by serum antibody. Furthermore, the results are consistent with the possibility, suggested by previous studies in volunteers, that susceptibility is determined by Norwalk virus-specific intestinal receptor sites. IgM responses to the Norwalk virus were detected in only seven persons who became ill (64%) and nine who seroconverted (56%). The seroassay for the Norwalk IgM component might have proved a more sensitive diagnostic tool in this outbreak if convalescent-phase specimens had been collected sooner than four weeks after the onset of illness.     

A Foodborne Norovirus Outbreak Due To Manually Prepared Salad, Austria 2006

Abstract Background: Norovirus is increasingly being recognized as a leading cause of foodborne disease. Nevertheless, welldocumented foodborne outbreaks due to norovirus are rarely found in the literature. Material and Methods: A retrospective cohort study was conducted for identifying the source of a gastroenteritis outbreak. A total of 325 persons were identified as the atrisk group. Results: The overall attack rate was 56% (182/325). Of the four working days of possible foodborne exposure to norovirus (Monday till Thursday), Wednesday (risk ratio [RR]: 18.82; 95%CI 11.82–29.96) and Thursday (RR 2.14; 95%CI 1.65–2.79) turned out to be the most likely days on which infections with norovirus occurred. The day-by-day food specific cohort analyses yielded consumption of salad on Wednesday (adjusted RR 2.82; 95%CI 1.0–7.94) to be associated with highest risk of illness. The most likely source of food contamination is a kitchen assistant having prepared salad manually. She fell ill with symptoms of gastroenteritis on Wednesday during the early working hours and continued working. Human stool samples obtained from five out of six outbreak cases, including the sick kitchen assistant, were RT-PCR positive for norovirus genotype GGII.7 (Leeds-like). Conclusion: This foodborne norovirus outbreak underlines the drastic consequences of neglecting the rules of basic kitchen hygiene. Food handlers working despite manifest diarrhea or vomiting – often in fear of job loss – are a common cause of foodborne norovirus outbreaks.     

Norovirus outbreaks in a teaching hospital: the role of infection control

In January 2004, 20 patients and 19 staff in one ward became ill in an outbreak of norovirus-related gastroenteritis over a 12-day period. The epidemic curve indicated person-to-person transmission. Infection control measures were instituted in consultation with the government health authorities. A prompt rigorous response may have prevented spread to other wards. In March 2004, 54 staff and 1 member of a patient's family became ill in an outbreak of gastroenteritis. The source of norovirus contamination was associated with food served at the hospital restaurant. Secondary infection was prevented because the outbreak was recognized early and staff members with gastroenteritis symptoms were asked to stay home. Immediate control measures, such as identification and announcement of the outbreak, isolation of symptomatic individuals from others, personal protection, helped control the infection.     

Epidemiological investigation of a food-borne gastroenteritis outbreak caused by Norwalk-like virus in 30 day-care centres

In March 1999, an outbreak of gastroenteritis occurred affecting 30 day-care centres served by the same caterer. A retrospective cohort study was performed in 13 randomly selected day-care centres to determine the source and mode of transmission. Electron microscopy and PCR were used to verify the diagnosis. The overall attack rate (AR) was 37% (195/524): 30% in children and 62% in adults. Modified by the age of the patient, eating pumpkin salad served on 1 March was associated with becoming an early case (odds ratio = 3.9; 95% confidence interval 1.8-8.8). No significant association was found between food consumption and becoming a late case. The primary food-borne AR was 27% and the secondary AR was 14%. The same genotype of Norwalk-like virus was found in 5 cases and in 1 ill and 1 asymptomatic food-handler. Contamination by 1 of the food-handlers seems the most likely route of spread of the virus and underlines the importance of strict hygienic routines.     

Serological and Epidemiological Analysis of an Outbreak of Gastroenteritis Among Military Recruits in Germany Caused by <Emphasis Type="Italic">Cryptosporidium parvum</Emphasis>

Background   Cryptosporidium spp. cause enteritic disease worldwide. Besides those patients with an impaired immune system, the general population is also at risk. Patients and Methods  Stool samples from participants of a military field exercise were tested for enteritic pathogens and sera were analyzed for Cryptosporidium-antibodies. All participants received a questionnaire for assessing possible risk factors. Results  After a 5-day field training, 201 of a total of 450 soldiers (45%) developed acute gastroenteritis. Immediate microbiological analysis ruled out enteropathogenic bacteria and viruses as the cause of the disease. Only after hospitalization of one of the patients diagnostic procedures were expanded to the identification of parasites and Cryptosporidium parvum was identified. In addition, 14 fecal samples of 217 specimens were subsequently identified in a Cryptosporidium antigen ELISA. A serological analysis of 214 sera revealed 72% positive for specific IgG antibodies compared with 17% of a control group of soldiers who had not participated in the field training (relative risk 3.38; 95% CI 2.39–4.77; p < 0.001). Analysis of specific IgM levels was less conclusive. Epidemiological analysis of questionnaires correlated drinking of tap water, or consumption of various meals with gastroenteritis. However, the source of contamination could not be identified. Conclusion   Cryptosporidium spp. can cause acute enteritis even in healthy, young adults as demonstrated by this outbreak. Using serological methods, the extent of the outbreak could be estimated in a retrospective analysis.     

Humoral immunity in infants with gastroenteritis caused by human calicivirus

To assess the serum immune response in infants with gastroenteritis caused by human calicivirus (HCV), we tested a total of 165 serum specimens for antibodies to HCV by a radioimmunoassay blocking (RIA-BL) test. The specificity of the RIA-BL test for antibody to HCV was established as follows: paired sera from patients with HCV gastroenteritis revealed significant rises in antibody to HCV, whereas there was no significant change in RIA-BL titer to HCV in paired sera collected from the same individuals when infected with other gastroenteritis viruses. We analyzed 41 paired sera from patients and from healthy contacts involved in an outbreak of HCV gastroenteritis. All 23 infants without preexisting antibody revealed a sharp rise in HCV titer, and 18 (73%) of 23 of them developed illness. Fifteen of 18 infants with preexisting antibody also revealed a significant rise in HCV antibody, but only 3 (16.7%) of 18 became ill (P less than .01). These data suggest that the presence of serum antibody may correlate with resistance to illness in HCV gastroenteritis.     

Food-borne outbreaks of gastroenteritis caused by small round structured viruses. 1. Four outbreaks of gastroenteritis associated with oyster consumption]

Between December 9, 1988 and January 28, 1989, there were four outbreaks of acute gastroenteritis in Saitama prefecture. Eighty-two of 123 persons (67%) attending four banquets in restaurants became ill: 44 cases attending three banquets were related to eating raw oysters, and 38 attending one banquet to eating sashimi. The most common symptoms were nausea, diarrhea, abdominal cramps, and vomiting. Average incubation periods were 29 to 32 hours long. Bacteriologic analysis of stool specimens did not reveal causative agents. Small round structured viruses were detected in fecal specimens from 19 of 39 ill persons (49%) by electron microscopy. In one of four outbreaks, the formation of antibody to small round structured virus in paired serum samples was detected by western blot test. Small round structured viruses were implicated as the etiologic agents in four outbreaks of acute gastroenteritis.     

Salmonella enteritidis gastroenteritis transmitted by intact chicken eggs

OBJECTIVE: To determine the source and to describe the clinical importance of a large outbreak of Salmonella enteritidis gastroenteritis in Tennessee, which is outside the geographic focus of the S. enteritidis pandemic. DESIGN: A case-control study and tracing of the source eggs. SETTING: A Tennessee community and a large layer farm in Indiana. PATIENTS: Case patients ate at the implicated restaurant and subsequently developed S. enteritidis gastroenteritis; controls ate with the case patients, but did not develop gastroenteritis. MEASUREMENTS: Eighty-one case patients were identified; 73 (90%) had eaten egg-containing sauces at a local restaurant on a given evening. The eggs were traced to their farm of origin in Indiana. The farm was inspected 5 weeks after the outbreak. MAIN RESULTS: Of 24 patients with culture-proved cases, 11 were hospitalized. Hollandaise and bernaise sauces prepared with intact, extra-large, grade-A eggs were strongly associated with illness (P less than 0.001). Salmonella enteritidis was isolated from specimens collected from chickens and the farm. Antimicrobial susceptibility patterns, phage typing, and plasmid profiles of isolates from the farm and from patients were indistinguishable. CONCLUSIONS: Salmonella enteritidis infection is a large and growing public health problem that is spreading beyond the northeastern United States. This study shows a direct link between infected poultry flocks and an outbreak of human illness.