Gastrointestinal, influenza-like illness and dermatological complaints following exposure to floodwater: a cross-sectional survey in The Netherlands.

Extreme rainfall events may cause pluvial flooding, increasing the transmission of several waterborne pathogens. However, the risk of experiencing clinically overt infections following exposure to pluvial floodwater is poorly estimated. A retrospective cross-sectional survey was performed to quantify the occurrence of self-reported gastrointestinal, influenza-like illness (ILI) and dermatological complaints, and the frequency of visits to the general practitioner (GP), during a 4-week observation period following pluvial flooding at seven locations in The Netherlands. Questionnaires were sent to 817 flooded households, 149 (17%) of which returned the questionnaire reporting information for 199 participants. Contact with floodwater was significantly associated with increased occurrence of gastrointestinal [odds ratio (OR 4·44)], ILI (OR 2·75) and dermatological (OR 6·67) complaints, and GP visits (OR 2·72). Having hand contact with floodwater was associated with gastrointestinal and dermatological complaints, whereas ILI complaints were associated with being engaged in post-flooding cleaning operations and having walked/cycled through floodwater. This study shows that floodwater-associated diseases occur in urban settings following extreme rainfall events in a high-income country. As pluvial floods are expected to escalate in the future due to global climate change, further research is warranted to determine the disease burden of pluvial flooding and to assess the effect of different interventions, including raising awareness among stakeholders.

Risk factors for sporadic Shiga toxin-producing Escherichia coli O157 and non-O157 illness in The Netherlands, 2008-2012, using periodically surveyed controls.

Shiga toxin-producing Escherichia coli (STEC) infections have been associated with severe illness. Ruminants are seen as the main reservoir and the major transmission route is considered to be foodborne. In The Netherlands, a case-control study was conducted, using data collected during 2008-2012. Patients were interviewed and controls completed a self-administered questionnaire. Patients travelling abroad were excluded from the analyses. STEC O157 and non-O157 were examined separately and differentiated into two age groups (<10 years, ⩾10 years). We included 130 O157 cases, 78 non-O157 cases and 1563 controls. In both age groups of O157 patients, raw spreadable sausage was the main risk factor for infection. For STEC non-O157 cases aged <10 years, contact with farm animals was the main risk factor and in non-O157 cases aged ⩾10 years, consumption of beef was the main risk factor. During 2008-2012, risk factors for STEC infections in the Dutch population differed between age groups and serogroup categories, and were related to eating meat and contact with farm animals. Advising the public about the risks of consuming raw or undercooked meat (products) and hygiene habits in case of contact with farm animals, could help in the prevention of STEC infections.

Risk factors for sporadic listeriosis in the Netherlands, 2008 to 2013.

Although the disease burden of listeriosis on population level is low, on individual level the impact is high, largely due to severe illness and a high case fatality. Identification of risk factors supports and specifies public health actions needed for prevention. We performed a case­control study to determine host- and food-related risk factors for non-perinatal listeriosis in the Netherlands. Patients with non-perinatal listeriosis reported between July 2008 and December 2013 were compared with controls from a periodic control survey who completed a questionnaire in the same period. Higher age, male sex, underlying disease, especially cancer and kidney disease, and use of immunosuppressive medicine were strong risk factors for acquiring non-perinatal listeriosis. Analysis of the food consumption in the group of cases and controls with underlying diseases did not reveal any high-risk food products. Information and advice should continue to be given to persons at risk of severe listeriosis. Univariate analyses indicate that patients using gastric acid inhibitors are at risk. It is worth adding these patients to the group of susceptible persons.

Campylobacteriosis in returning travellers and potential secondary transmission of exotic strains.

SUMMARY: Multilocus sequence types (STs) were determined for 232 and 737 Campylobacter jejuni/coli isolates from Dutch travellers and domestically acquired cases, respectively. Putative risk factors for travel-related campylobacteriosis, and for domestically acquired campylobacteriosis caused by exotic STs (putatively carried by returning travellers), were investigated. Travelling to Asia, Africa, Latin America and the Caribbean, and Southern Europe significantly increased the risk of acquiring campylobacteriosis compared to travelling within Western Europe. Besides eating chicken, using antacids, and having chronic enteropathies, we identified eating vegetable salad outside Europe, drinking bottled water in high-risk destinations, and handling/eating undercooked pork as possible risk factors for travel-related campylobacteriosis. Factors associated with domestically acquired campylobacteriosis caused by exotic STs involved predominantly person-to-person contacts around popular holiday periods. We concluded that putative determinants of travel-related campylobacteriosis differ from those of domestically acquired infections and that returning travellers may carry several exotic strains that might subsequently spread to domestic populations even through limited person-to-person transmission.

Emergence of Escherichia coli encoding Shiga toxin 2f in human Shiga toxin-producing E. coli (STEC) infections in the Netherlands, January 2008 to December 2011.

The Shiga toxins of Shiga toxin-producing Escherichia coli (STEC) can be divided into Shiga toxin 1 (Stx1) and Shiga toxin 2 (Stx2) with several sub-variants. Variant Stx2f is one of the latest described, but has been rarely associated with symptomatic human infections. In the enhanced STEC surveillance in the Netherlands, 198 STEC O157 cases and 351 STEC non-O157 cases, including 87 stx2f STEC isolates, were reported between 2008 and 2011. Most stx2f strains belonged to the serogroups O63:H6 (n=47, 54%), O113:H6 (n=12, 14%) and O125:H6 (n=12, 14%). Of the 87 stx2f isolates, 84 (97%) harboured the E. coli attaching and effacing (eae) gene, but not the enterohaemorrhagic E. coli haemolysin (hly) gene. stx2f STEC infections show milder symptoms and a less severe clinical course than STEC O157 infections. Almost all infections with stx2f (n=83, 95%) occurred between June and December, compared to 170/198 (86%) of STEC O157 and 173/264 (66%) of other STEC non-O157. stx2f STEC infections in the Netherlands are more common than anticipated, and form a distinct group within STEC with regard to virulence genes and the relatively mild disease.

An outbreak of Salmonella Newport associated with mung bean sprouts in Germany and the Netherlands, October to November 2011.

The largest Salmonella enterica serovar Newport outbreak (n=106) ever reported in Germany occurred in October and November 2011. Twenty associated cases were reported in the Netherlands. The outbreak investigation included an analytical epidemiological study, molecular typing of human and food isolates and food traceback investigations. Unspecified Salmonella had been detected in samples of mung bean sprouts at a sprout producer (producer A) in the Netherlands and mung bean sprouts contaminated with S. Newport had been found during routine sampling at a sprout distributor in Germany. Therefore, we tested the hypothesis of sprouts being the infection vehicle. In a case-control study, we compared 50 notified adult S. Newport cases with 45 Salmonella enterica serovar Enteritidis cases regarding their food consumption in the three days before illness. In multivariable logistic regression analysis, only sprout consumption was significantly associated with S. Newport infection (odds ratio: 18.4; 95% confidence interval: 2.2-150.2). Molecular typing patterns of human isolates were indistinguishable from a mung bean sprouts isolate. Traceback of sprouts led to distributors and producer A in the Netherlands. Since sprouts are frequently contaminated with microorganisms, consumers need to be aware that consumption of raw or insufficiently cooked sprouts may pose a health risk.

Large outbreak of Salmonella Thompson related to smoked salmon in the Netherlands, August to December 2012.

On 15 August 2012, an increase in the number of Salmonella Thompson cases was noticed by the Salmonella surveillance in the Netherlands. A case­control study was performed, followed by a food investigation. In total 1,149 cases were laboratory-confirmed between August and December 2012 of which four elderly (76­91 years) were reported to have died due to the infection. The cause of the outbreak was smoked salmon processed at a single site. The smoked salmon had been continuously contaminated in the processing lines through reusable dishes, which turned out to be porous and had become loaded with bacteria. This is the largest outbreak of salmonellosis ever recorded in the Netherlands. The temporary closure of the processing site and recall of the smoked salmon stopped the outbreak. An estimated four to six million Dutch residents were possibly exposed to the contaminated smoked salmon and an estimated 23,000 persons would have had acute gastroenteritis with S. Thompson during this outbreak. This outbreak showed that close collaboration between diagnostic laboratories, regional public health services, the national institute for public health and the food safety authorities is essential in outbreak investigations.

Brachyspira species and gastroenteritis in humans.

Brachyspira species have been implicated as a potential cause of gastroenteritis in humans; this is, however, controversial. In 733 gastroenteritis cases and 464 controls, we found 29 samples positive for Brachyspira species (2.3% of cases and 2.6% of controls; P = 0.77). Brachyspira species were not associated with gastroenteritis in humans.

Increased risk for Campylobacter jejuni and C. coli infection of pet origin in dog owners and evidence for genetic association between strains causing infection in humans and their pets.

We compared Campylobacter jejuni/coli multilocus sequence types (STs) from pets (dogs/cats) and their owners and investigated risk factors for pet-associated human campylobacteriosis using a combined source-attribution and case-control analysis. In total, 132/687 pet stools were Campylobacter-positive, resulting in 499 strains isolated (320 C. upsaliensis/helveticus, 100 C. jejuni, 33 C. hyointestinalis/fetus, 10 C. lari, 4 C. coli, 32 unidentified). There were 737 human and 104 pet C. jejuni/coli strains assigned to 154 and 49 STs, respectively. Dog, particularly puppy, owners were at increased risk of infection with pet-associated STs. In 2/68 cases vs. 0.134/68 expected by chance, a pet and its owner were infected with an identical ST (ST45, ST658). Although common sources of infection and directionality of transmission between pets and humans were unknown, dog ownership significantly increased the risk for pet-associated human C. jejuni/coli infection and isolation of identical strains in humans and their pets occurred significantly more often than expected.

Unusual increase in reported cases of paratyphoid A fever among travellers returning from Cambodia, January to September 2013.

From January to September 2013, a marked increase in notifications of Salmonella Paratyphi A infections among travellers returning from Cambodia occurred in France. An investigation revealed 35 cases without a common source: 21 in France, five in Germany, three in the Netherlands, one in Norway, one in the United Kingdom, four in New-Zealand. Data suggest an ongoing event that should trigger further investigation. Travellers to Cambodia should observe preventive measures including good personal hygiene and food handling practices.

Costs of gastroenteritis in the Netherlands, with special attention for severe cases.

In 1999, the costs of gastroenteritis in the Netherlands were estimated using data on hospitalizations from national registries, together with data on etiology and self-reported data on health care resource use in a community-based study. Now, more information on hospitalizations is available and these data were used to update the total costs of gastroenteritis in the Netherlands. The costs of severe gastroenteritis in the Netherlands were estimated in more depth using a hospital-based study, with patient questionnaires including a follow-up period of 6 months. The overall costs of gastroenteritis were calculated taking direct medical costs, direct non-medical costs, and indirect non-medical costs into account. The costs for severe gastroenteritis in 2009 were estimated at 2,203 per hospitalized child and 6,834 per hospitalized adult. The overall costs of gastroenteritis in 2009 were estimated at 611-695 million, which is 133-151 per gastroenteritis case or 37-42 per inhabitant. The total health care costs for gastroenteritis were about 50% higher in 2009 compared to 1999, which is mostly due to the rise in health care costs. The costs per gastroenteritis episode in adults are higher compared to children, mainly due to differences in the reasons for hospitalization and course of disease, and productivity losses.

Etiology of acute gastroenteritis in children requiring hospitalization in the Netherlands.

Infectious gastroenteritis causes a considerable burden of disease worldwide. Costs due to gastroenteritis are dominated by the hospitalized cases. Effective control of gastroenteritis should be targeted at the diseases with the highest burden and costs. For that, an accurate understanding of the relative importance of the different bacterial, viral, and parasitic pathogens is needed. The objective of the present study was to determine the incidence and etiology of gastroenteritis requiring hospital admission in the Netherlands. Six hospitals enrolled patients admitted with gastroenteritis for approximately one year over the period May 2008 to November 2009. Participants provided questionnaires and a fecal sample, and the hospital filled out a clinical questionnaire. In total, 143 children hospitalized for gastroenteritis and 64 matched controls were included in the study. Overall incidence of gastroenteritis requiring hospitalization was estimated at 2.92 per 1,000 children aged 0-17 years per year, with the highest incidence in children under the age of 5 years. The full diagnostic panel of pathogens could be studied in fecal samples of 96 cases. One or more pathogens were found in 98% of these cases. Co-infections were observed relatively often (40%). Viruses were detected in 82% of the samples, with rotavirus being most common (56%), bacteria in 32% and parasites in 10%. The present study emphasizes the importance of viral pathogens, especially rotavirus, in hospitalizations of children with gastroenteritis. Policies to reduce (costs of) hospitalizations due to gastroenteritis should therefore be first targeted at rotavirus.

Aetiology of acute gastroenteritis in adults requiring hospitalization in The Netherlands.

SUMMARY Infectious gastroenteritis causes a considerable burden of disease worldwide. Effective control should be targeted at diseases with the highest burden and costs. Therefore, an accurate understanding of the relative importance of the different microorganisms is needed. The objective of this study was to determine the incidence and aetiology of gastroenteritis in adults requiring hospital admission in The Netherlands. Five hospitals enrolled patients admitted with gastroenteritis for about 1 year during the period May 2008 to November 2009. Participants completed questionnaires and provided a faecal sample. The hospital completed a clinical questionnaire. In total, 44 adults hospitalized for gastroenteritis were included in the study. The cases had serious symptoms, with 31% subsequently developing kidney failure. One or more pathogens were found in 59% of cases. Overall, rotavirus (22%) was the most common infection. Co-infections were observed relatively often (22%). This study emphasizes that rotavirus can also cause serious illness in adults.

Outbreak of Salmonella Thompson in the Netherlands since July 2012.

An ongoing outbreak of salmonellosis due to Salmonella Thompson is affecting the Netherlands. Between 2 August and 19 October 2012, 866 cases were confirmed. Their median age was 44 years (range: 0-95 years), 63% were female and 36% were hospitalised. A matched case-control study suggested smoked salmon as the vehicle. Salmonella Thompson was confirmed in four of nine batches of smoked salmon from one producer. A recall of all concerned smoked salmon products was executed starting end of September.

Geographical association between livestock density and human Shiga toxin-producing Escherichia coli O157 infections.

Shiga toxin-producing Escherichia coli (STEC) bacteria can cause outbreaks and sporadic cases of gastroenteritis in humans. Ruminants are seen as the main reservoir. The aim of this study was to evaluate the spatial association between reported human STEC O157 infections in The Netherlands and different livestock densities. Data were collected at the municipality level and a spatial regression analysis was performed. Between April 1999 and December 2008, 409 symptomatic sporadic cases were registered. Adding an interaction term between season, age, and livestock density showed an increased risk of STEC cases in summer for living in areas with cattle, in particular for young children. In conclusion, cattle, but not pigs or poultry, are indicated as an important source for human STEC O157 infections in rural areas. The association is probably due to direct or indirect contact with cattle, resulting in symptomatic infections, especially in young children.

National outbreak of Salmonella Typhimurium (Dutch) phage-type 132 in the Netherlands, October to December 2009.

Between October and December 2009, 23 cases of Salmonella Typhimurium (Dutch) phage type 132, each with an identical multiple-locus variable-number tandem-repeat analysis (MLVA) profile (02-20-08-11-212), were reported from across the Netherlands. A case­control study was conducted using the food-consumption component of responses to a routine population-based survey as a control group. The mean age of cases was 17 years (median: 10 years, range: 1­68). Sixteen cases were aged 16 years or under. Raw or undercooked beef products were identified as the probable source of infection. Consumers, in particular parents of young children, should be reminded of the potential danger of eating raw or undercooked meat.

Norovirus outbreaks in nursing homes: the evaluation of infection control measures.

Effective infection control measures during norovirus outbreaks are urgently needed in places where vulnerable individuals gather. In the present study, the effect of a number of measures was investigated in daily practice. Forty-nine Dutch nursing homes were monitored prospectively for norovirus outbreaks during two winter seasons. A total of 37 norovirus outbreaks were registered. Control measures were most effective when implemented within 3 days after onset of disease of the first patient. Measures targeted at reduced transmission between persons, via aerosols, and via contaminated surfaces reduced illness in staff and in residents. Reducing illness in staff results in fewer costs for sick leave and substitution of staff and less disruption in the care of residents. The effect of control measures on outbreak duration was limited. This is the first intervention study examining the effect of control measures. Further research is needed to extend and refine the conclusions.

Nationwide outbreak of STEC O157 infection in the Netherlands, December 2008-January 2009: continuous risk of consuming raw beef products.

The Netherlands experienced a nationwide outbreak of Shiga toxin-producing Escherichia coli (STEC) O157 with onset of symptoms from the end of December 2008 until the end of January 2009. A total of 20 laboratory-confirmed cases were linked to the outbreak strain, serotype O157: H-, stx1, stx2, eae and e-hly positive. The investigation into the source of this outbreak is still ongoing, but evidence so far suggests that infection occurred as a result of consuming contaminated raw meat (steak tartare).

Prevalence, characterisation and clinical profiles of Shiga toxin-producing Escherichia coli in The Netherlands.

Detection of Shiga toxin-producing Escherichia coli (STEC) in The Netherlands is traditionally limited to serogroup O157. To assess the relative importance of STEC, including non-O157 serogroups, stool samples submitted nationwide for investigation of enteric pathogens or diarrhoea were screened with real-time PCR for the presence of the Shiga toxin genes. Patients were selected if their stool contained blood upon macroscopic examination, if they had a history of bloody diarrhoea, were diagnosed with haemolytic uraemic syndrome, or were aged <6 years (irrespective of the bloody aspect of the stool). PCR-positive stools were forwarded to a central laboratory for STEC isolation and typing. In total, 4069 stools were examined, with 68 (1.7%) positive PCR results. The highest prevalence was for stools containing macroscopic blood (3.5%), followed by stools from patients with a history of bloody diarrhoea (2.4%). Among young children, the prevalence (1.0%) was not significantly higher than among random, non-bloody, stool samples from diarrhoeal patients (1.4%). STEC strains were isolated from 25 (38%) PCR-positive stools. Eleven O-serogroups were detected, including five STEC O157 strains. As serogroup O157 represented only 20% of the STEC isolates, laboratories should be encouraged to use techniques enabling them to detect non-O157 serogroups, in parallel with culture, for isolation and subsequent characterisation of STEC strains for public health surveillance and detection of outbreaks.

An international outbreak of Shiga toxin-producing Escherichia coli O157 infection due to lettuce, September-October 2007.

Between 14 September and 20 October 2007, an outbreak of Shiga toxin-producing Escherichia coli (STEC) O157 simultaneously occurred in the Netherlands and Iceland. A total of 50 laboratory-confirmed cases were reported with a STEC O157 infection caused by the same clone. The strain was of type O157:H-, PT8, positive for stx1, stx2, eae and e-hly, and sorbitol negative. The most probable cause of this international outbreak was contaminated lettuce, shredded and pre-packed in a Dutch food processing plant. Samples of the environment, raw produce and end products, taken at several vegetable growers and processing plants all tested negative for STEC O157. However, the only epidemiological link between the cases in the Netherlands and in Iceland was the implicated Dutch processing plant. In Europe, food products are often widely distributed posing the risk of potential spread of food borne pathogens simultaneously to several countries. This international outbreak emphasises the importance of common alert and surveillance systems in earlier detection of international outbreaks and better assessment of their spread.