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.

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.

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.

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.

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.

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.

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.

Internet-based monitoring of influenza-like illness in the general population: experience of five influenza seasons in The Netherlands.

Like in most other countries, influenza surveillance in The Netherlands is based upon influenza-like illness (ILI) consultations reported by sentinel general practitioners (GP). In addition, an internet-based monitoring of ILI in the general population started in 2003/2004 (Great Influenza Survey (GIS)). We compared GIS results over 5 influenza seasons with results from the GP system. Weekly ILI incidence from GIS correlated well with ILI incidence from the GP system the same week and even better 1 week later. This suggests that GIS is useful for early detection of trends in influenza activity. However, two important vulnerable groups, children and the elderly, are clearly underrepresented in the GIS. Furthermore, virological confirmation is lacking in the GIS. So, GIS can be a useful addition to the GP system, especially when representativeness can be improved and when participation remains at the current high level.

Differences in clinical presentation between norovirus genotypes in nursing homes.

BACKGROUND: In healthcare settings, norovirus (NoV) outbreaks are predominated by genotype II.4 (GII.4) strains. Periodically, new variants of GII.4 emerge, causing a temporary increase of outbreaks. OBJECTIVES: To study the relationship between symptoms and NoV genotype. STUDY DESIGN: Data of 49 nursing homes which were monitored for NoV outbreaks in the winter seasons of 2005/2006 and/or 2006/2007 were used. RESULTS: Data on symptoms and duration of illness were available for 465 residents and 174 staff members from 28 NoV outbreaks. Genotype GII.4 was responsible for 21 outbreaks. Attack rates for residents seemed to be higher in GII.4 outbreaks compared to other genotypes. In outbreaks caused by GII.4, residents vomited more often than in outbreaks with other genotypes. They also had more often complaints of nausea, abdominal cramps, fever, and mucus in stool. The GII.4 2004 variant outbreaks showed higher percentages of nausea, stomach ache, and fever than outbreaks with the GII.4 2006a variant. Differences in duration of illness were not found. In nursing home staff, no clear differences were found between outbreaks caused by GII.4 and non-GII.4 NoVs. CONCLUSIONS: Genotype GII.4 was found to be related to more symptomatic disease, including more residents vomiting, and to a lesser extent, higher attack rates among residents.

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.

Multiple exposures during a norovirus outbreak on a river-cruise sailing through Europe, 2006.

In the summer of 2006, several cruise-related viral gastroenteritis outbreaks were reported in Europe. One report came from a river-cruise, belonging to a ship-owner who had two other ships with outbreaks. This situation warranted onsite investigation in order to identify a potential common source of infection. A retrospective cohort study was performed among 137 people on board. Epidemiological questionnaire data were analysed using logistic regression. Stool, food, water and surface samples were collected for norovirus detection. Norovirus GGII.4-2006b was responsible for 48 gastroenteritis cases on this ship as confirmed in six patients. Identical norovirus sequences were detected in stool samples, on surfaces and in tap water. Epidemiological and microbiological data indicated multiple exposures contributing to the outbreak. Microbiological results demonstrated person-to-person transmission to be clearly present. Epidemiological results indicated that consuming tap water was a risk factor; however, this could not be concluded definitively on the basis of the available data. A common source for all cruise-related outbreaks was unlikely. The ongoing outbreaks on this ship demonstrated that evidence based guidelines on effective disinfection strategies are needed.

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.

Alcohol intake and cardiovascular disease and mortality: the role of pre-existing disease.

OBJECTIVES: Pre-existing conditions have been postulated as possible causes of the J-shaped relationship between alcohol intake and cardiovascular disease. Two research questions have been addressed in this paper. First, whether never drinkers and former drinkers differ from moderate drinkers in terms of health, and if so, which health problems contribute to this difference. Second, whether the U-shaped relationship between current alcohol intake and cardiovascular disease or all-cause mortality could in part be explained by difference in pre-existing disease burden. DESIGN, SETTING AND PARTICIPANTS: A prospective case-cohort, the Lifestyle and Health Study, consisting of 16,210 men and women aged between 45 and 70 years. Alcohol intake and risk factors were assessed at baseline with a self-administered questionnaire. Medical information was obtained from general practitioners. Cardiovascular events and mortality were followed for a period of 5 years (1996-2001). MAIN RESULTS: Never drinkers and former drinkers were less healthy than moderate drinkers. They rated their health more often as poor, and often had more diseases, such as cardiovascular disease, diabetes, and also alcohol-related diseases. The difference in disease burden did not change the observed relationship between alcohol intake and cardiovascular events, and only partially changed the U-shaped relationship between alcohol intake and all-cause mortality. CONCLUSIONS: The found difference in health between never drinkers and former drinkers compared with moderate drinkers appeared to be only a partial explanation of the observed relationships between alcohol intake and cardiovascular disease, and between alcohol intake and all-cause mortality.

Shiga toxin-producing Escherichia coli (STEC) O157 outbreak, The Netherlands, September-October 2005.

In September 2005, the first national food-related outbreak of Shiga toxin (Stx)-producing Escherichia coli (STEC) O157 was investigated in the Netherlands. A total of 21 laboratory-confirmed cases (including one secondary case), and another 11 probable cases (two primary and nine secondary cases) were reported in patients who became ill between 11 September and 10 October 2005. Preliminary investigation suggested consumption of a raw beef product, steak tartare (in the Netherlands also known as "filet americain"), and contact with other symptomatic persons as possible risk factors. A subsequent case-control study supported the hypothesis that steak tartare was the source of the outbreak (matched odds ratio (OR) 272, 95% confidence interval (CI) 3-23,211). Consumption of ready-to-eat vegetables was also associated with STEC O157 infection (matched OR 24, 95% CI 1.1-528), but was considered a less likely source, as only 40% of the cases were exposed. Samples of steak tartare collected from one chain of supermarkets where it is likely that most patients (67%) bought steak tartare, all tested negative for STEC O157. However, sampling was done three days after the date of symptom onset of the last reported case. Since 88% of the cases became ill within a two week period, point source contamination may explain these negative results. It is concluded that steak tartare was the most likely cause of the first national food-related outbreak of STEC O157 in the Netherlands.

Lower prevalence of heart disease but higher mortality risk during follow-up was found among nonrespondents to a cohort study.

OBJECTIVE: The primary aim was to assess the association between response behavior and health status at baseline, and survival in a 5-year follow-up period. A secondary aim was to assess whether reasons for nonresponse were associated with health status at baseline. STUDY DESIGN AND SETTING: Data came from a prospective study cohort consisting of 31,349 men and women aged 45-70 years. Objective retrospective and prospective health information derived from general practitioner registries was available for both respondents and nonrespondents. RESULTS: Results show that among respondents coronary heart disease was more prevalent. Compared with respondents, noncontacts had a higher mortality risk during follow-up. Refusals had hypercholesterolemia more often than did noncontacts, and coronary heart disease or diabetes mellitus less often. CONCLUSION: The paradoxical results that respondents are less healthy at baseline but prospectively have a lower mortality risk may point to a selection effect indicating that the 'worried ill' are more inclined to participate. This effect could imply that observed relationships between risk factors or behaviors and outcomes in cohort studies may be attenuated.

Measurement of lifetime alcohol intake: utility of a self-administered questionnaire.

Prior epidemiologic research revealing cardioprotective effects of alcohol intake has systematically neglected lifetime exposure to alcohol, which may cause serious bias in conclusions regarding drinking and heart disease risk. Departing from use of an earlier interview schedule, the authors of the present 1996-2001 cohort study developed a self-administered Lifetime Drinking History questionnaire (LDH-q). A total of 16,211 Dutch men and women older than age 45 years participated by completing the baseline questionnaire. A random sample of 3,255 men and women was used to determine the reliability and validity of the LDH-q. Test-retest reliability was assessed by means of the intraclass correlation coefficient and kappa scores. Correlations between lifetime and current intake scores were used to assess discriminant and convergent validity. Both reliability and validity appeared to be reasonably high compared with results obtained by using interview formats to measure lifetime alcohol intake. Reliability of the LDH-q was higher for men than for women, probably because of the more frequent and regular drinking of men. Indices of validity were similar for men (0.75) and women (0.70). Results show that the LDH-q can be a useful instrument in large-scale cohort studies.

[Reported cases of Legionella pneumonia in the Netherlands, 1987-2000]. / Gemelde Legionella-pneumonie in Nederland, 1987-2000.

OBJECTIVE: To describe the incidence and mortality of legionnaires' disease (LD) in the Netherlands on the basis of registration, with a focus on possible sources of infection, and geographic and seasonal variations. DESIGN: Retrospective, descriptive. METHOD: The incidence and mortality rate of LD from July 1987 until December 2000 was described using registration data from the Dutch Health Inspectorate. Possible sources of infection were also listed (patients involved in the Bovenkarspel outbreak (1999) were excluded). Geographic variations in occurrence of LD were investigated by incidences computed per province. To gain insight into the possible existence of seasonal variations the mean numbers of patients per month were compared. RESULTS: During the period of interest a total of 806 persons with LD were reported, 36 of whom were excluded. The mean incidence rose from 0.27 cases per 100,000 inhabitants in the 1987-1998 period to 0.91 cases per 100,000 inhabitants in the 1999-2000 period. The male:female ratio was 2.6:1. A total of 96 persons (12.5%) died as a result of LD. There were more deaths in the group of patients with confirmed LD compared to the group of patients with probable LD. After 1998 the case fatality rate was lower than in the previous period (Fisher's exact test: p = 0.005). The potential source of infection was situated in the open population in 92.9% of cases. In 7.1% of cases the potential source was situated in a hospital. The incidence per province varied from 0.13 per 100,000 (Drente) to 0.66 per 100,000 (Limburg). During the summer months more patients were reported, most of whom had contracted the infection abroad. In contrast to the 1987-1998 period, after 1998 the incidence in the Netherlands was higher than the European mean and the incidence of confirmed LD was higher than in the United States.