Predictors of possible exposure to rabies in travellers: A case-control study.

BACKGROUND: Timely administration of post-exposure prophylaxis (PEP) can prevent rabies. For non-vaccinated persons, PEP consists of multiple vaccinations and rabies immunoglobulin (RIG) on indication. Since RIG is scarce, the need for PEP could be restricted through preventing animal contact and pre-exposure vaccination. We aimed to identify determinants for possible rabies exposure among travellers to provide more targeted pre-travel advice. METHOD: A case-control study was performed. Cases were defined as persons with a possible rabies exposure (category II or III injury according to WHO classification guidelines) in a rabies endemic country. Controls did not report exposure during travel. Multivariable logistic regression was performed. RESULTS: 229 cases and 1427 controls were included. Predictors (p < 0.05) of possible rabies exposure were young age, male sex, travelling to Western or Southeastern Asia, visiting a monkey park, pet ownership, previously visited the same country and considering oneself an experienced traveller. Negative predictors were travelling for business, visiting friends and relatives, and fear of animals. CONCLUSIONS: Pre-travel advice should take the identified predictors into account to provide better targeted information and pre-exposure prophylaxis.

Infection risks of city canal swimming events in the Netherlands in 2016.

INTRODUCTION: Swimming events in city canals are gaining popularity in the Netherlands, even though canal water is usually not officially designated for recreational use. Knowledge regarding the risk of infection after swimming in canals is limited. An outbreak was reported in 2015 following a canal swimming event in Utrecht, the Netherlands. Local governments were concerned about the health risks of such events. In order to assess the safety of canal swimming, the Public Health Service (PHS) prospectively investigated two city canal swimming events in 2015. In 2016, we repeated this study, aiming to prospectively determine the risks of infection during two urban swimming events, the Utrecht SingelSwim 2016 (USS) and the Amsterdam City Swim 2016 (ACS). METHODS: We sent online questionnaires to 271 USS participants and 2697 ACS participants, concerning personal characteristics, symptoms, and exposure. Participants were asked to forward the questionnaire to three relatives, i.e., non-exposed. We analyzed water samples from the USS venue taken during the event, as well as stool samples of USS participants with acute gastrointestinal illness (AGI). AGI was defined as diarrhea and/or vomiting within seven days after the event. We calculated adjusted risk ratios (RR) for AGI in the exposed group compared with non-exposed respondents, using binomial regression models. RESULTS: The questionnaire was returned by 160 USS participants (exposed) (59%) and 40 non-exposed relatives. Five percent of the exposed (n = 17) and 3% of non-exposed (n = 1) reported AGI (RR = 1.69; 95% CI: 0.23-12.46). Norovirus genogroup II was detected in two of six USS water samples and in none of the three stool samples. In one of three stool samples, rotavirus was detected. The questionnaire was returned by 1169 ACS participants (exposed) (43%) and 410 non-exposed relatives. Six percent of the exposed (n = 71) and 1% of non-exposed (n = 5) reported AGI (RR 4.86; 95% CI: 1.98-11.97). CONCLUSION: Results of the ACS event showed a higher risk for AGI among the exposed, indicating that participants of events in urban canals in the Netherlands could be at a higher risk for AGI than those not participating. The inconclusive results from the USS are likely due to the small sample size. Swimming in non-monitored open water can bring health risks and more knowledge about environmental and human risk factors helps reduce the risk by being able to more specifically advise organizations and governments.

Low and declining attack rates of imported typhoid fever in the Netherlands 1997-2014, in spite of a restricted vaccination policy.

BACKGROUND: Typhoid fever mainly occurs in (sub) tropical regions where sanitary conditions remain poor. In other regions it occurs mainly among returning travelers or their direct contacts. The aim of this study was to evaluate the current Dutch guidelines for typhoid vaccination. METHOD: Crude annual attack rates (AR) per 100,000 Dutch travelers were calculated during the period 1997 to 2014 by dividing the number of typhoid fever cases by the estimated total number of travelers to a specific country or region. Regions of exposure and possible risk factors were evaluated. RESULTS: During the study period 607 cases of typhoid fever were reported. Most cases were imported from Asia (60%). Almost half of the cases were ethnically related to typhoid risk regions and 37% were cases visiting friends and relatives. The overall ARs for travelers to all regions declined significantly. Countries with the highest ARs were India (29 per 100,000), Indonesia (8 per 100,000), and Morocco (10 per 100,000). There was a significant decline in ARs among travelers to popular travel destinations such as Morocco, Turkey, and Indonesia. ARs among travelers to intermediate-risk areas according to the Dutch guidelines such as Latin America or Sub-Saharan Africa remained very low, despite the restricted vaccination policy for these areas compared to many other guidelines. CONCLUSION: The overall AR of typhoid fever among travelers returning to the Netherlands is very low and has declined in the past 20 years. The Dutch vaccination policy not to vaccinate short-term travelers to Latin-America, Sub-Saharan Africa, Thailand and Malaysia seems to be justified, because the ARs for these destinations remain very low. These results suggest that further restriction of the Dutch vaccination policy is justified.

Seroprevalence of hepatitis E virus differs in Dutch and first generation migrant populations in Amsterdam, the Netherlands: a cross-sectional study.

BACKGROUND: In the last decade hepatitis E virus (HEV) is increasingly recognized as a cause of acute viral hepatitis in developed countries. HEV is transmitted via the fecal-oral route. In countries like the Netherlands, HEV infection is suspected to be a zoonosis but HEV may also be introduced by migrants. We studied the seroprevalence of HEV among different migrants, mainly Moroccans and Turks, and compared this to that of the native Dutch population in Amsterdam, the Netherlands. METHODS: Data were obtained from a cross-sectional survey of the adult Amsterdam population performed in 2004; the Amsterdam Health Monitor. A total of 1199 plasma samples were tested for IgG-and IgM antibodies to HEV using the Wantai kit according to instructions of the manufacturer. Basic demographic data (gender, age, country of birth, and age at immigration) were used in the analyses. Hepatitis A virus (HAV) serology data were available from a previous study. RESULTS: The total weighted anti-HEV IgG seroprevalence in the overall Amsterdam population was 26.7 %, based on 1199 samples. In the study population (not-weighted) this HEV seroprevalence was 157/426 (36.9 %) for the Dutch participants and it was 161/257 (62.6 %) for Moroccans, 99/296 (33.4 %) for Turks and 42/220 (19.1 %) for other ethnicities. HEV seroprevalence increased significantly with age. First-generation Moroccan migrants (44.0 %) had a significantly higher weighted HEV seroprevalence than the Dutch participants (29.7 %). In the first generation Turks (20.3 %) and first generation migrants from other countries (16.7 %) this weighted seroprevalence was lower, but this was only significant for the 'other ethnicities'. The median age of migration was significantly higher in the Moroccan and Turkish migrants who were HEV IgG positive versus HEV IgG negative. However, when stratifying for age at time of study, median migration age was only significantly different for HEV sero-status for younger Turks and younger 'other ethnicities'. HEV IgM antibodies were found in 0.6 % (n = 7) of participants and none were positive for HEV RNA, showing that there were no acute infections. Despite the common route of fecal-oral transmission for both viruses, there was no relation between HEV and HAV seropositivity. CONCLUSION: Within the multi-ethnical capital city of Amsterdam the HEV seroprevalence in first generation migrant populations differed from each other and from the autochthonous Dutch population. The relation between being HEV seropositive and a higher median age of migration suggests that younger migrants got more often infected in their country of origin than in the Netherlands.

Travel to Asia and traveller's diarrhoea with antibiotic treatment are independent risk factors for acquiring ciprofloxacin-resistant and extended spectrum ß-lactamase-producing Enterobacteriaceae-a prospective cohort study.

Travel to (sub)tropical countries is a well-known risk factor for acquiring resistant bacterial strains, which is especially of significance for travellers from countries with low resistance rates. In this study we investigated the rate of and risk factors for travel-related acquisition of extended spectrum ß-lactamase-producing Enterobacteriaceae (ESBL-E), ciprofloxacin-resistant Enterobacteriaceae (CIPR-E) and carbapenem-resistant Enterobacteriaceae. Data before and after travel were collected from 445 participants. Swabs were cultured with an enrichment broth and sub-cultured on selective agar plates for ESBL detection, and on plates with a ciprofloxacin disc. ESBL production was confirmed with the double-disc synergy test. Species identification and susceptibility testing were performed with the Vitek-2 system. All isolates were subjected to ertapenem Etest. ESBL and carbapenemase genes were characterized by PCR and sequencing. Twenty-seven out of 445 travellers (6.1%) already had ESBL-producing strains and 45 of 445 (10.1%) travellers had strains resistant to ciprofloxacin before travel. Ninety-eight out of 418 (23.4%) travellers acquired ESBL-E and 130 of 400 (32.5%) travellers acquired a ciprofloxacin-resistant strain. Of the 98 ESBL-E, predominantly Escherichia coli and predominantly blaCTX-M-15, 56% (55/98) were resistant to gentamicin, ciprofloxacin and co-trimoxazole. Multivariate analysis showed that Asia was a high-risk area for ESBL-E as well as CIPR-E acquisition. Travellers with diarrhoea combined with antimicrobial use were significantly at higher risk for acquisition of resistant strains. Only one carbapenemase-producing isolate was acquired, isolated from a participant after visiting Egypt. In conclusion, travelling to Asia and diarrhoea combined with antimicrobial use are important risk factors for acquiring ESBL-E and CIPR-E.

HPV vaccination intention among male clients of a large STI outpatient clinic in Amsterdam, the Netherlands.

We explored HPV vaccination intention and its determinants among male clients of the sexually transmitted infections (STI) clinic in Amsterdam. In 2015, male clients aged ≥18 years were invited to complete a web-based questionnaire regarding HPV vaccination intention and socio-psychological determinants. Determinants (scale -3 to +3) were assessed with linear regression, stratified for men who have sex with men (MSM) (including men who have sex with men and women) and men who only have sex with women (MSW). Additionally, we explored the effect of out-of-pocket payment on intention. Of 1490 participants (median age 33 years [IQR:25-44]), 1,053(71%) were MSM. HPV vaccination intention was high (mean 1.68, 95%CI:1.55-1.81 among MSW; mean 2.35, 95%CI:2.29-2.42 among MSM). In multivariable analyses, socio-psychological determinants had similar effects on intention in both groups (R2=0.70 among MSW; R2=0.68 among MSM), except for subjective norms, self-efficacy, and HPV knowledge (significantly stronger associations among MSW). HPV vaccination intention decreased significantly when vaccination would require out-of-pocket payment; intention was negative at the current list price (€350). HPV vaccination intention among male clients of the Amsterdam STI-clinic is high and variance in intention was mostly be explained by socio-psychological factors. Out-of-pocket payment had a strong negative effect on HPV vaccination intention.

Population-based study on the seroprevalence of parvovirus B19 in Amsterdam.

A study was undertaken to estimate the seroprevalence of parvovirus B19 infection in the general adult population of Amsterdam, The Netherlands. To our knowledge this is the first study testing parvovirus B19 in a random sample of the Dutch adult population. The study was a cross-sectional survey, and the study sample was stratified by age and ethnicity, with deliberate oversampling of minority ethnic groups. Serum samples obtained from 1,323 residents in 2004 were tested for antibodies to parvovirus B19. Basic demographic data (gender, age, country of birth, and number of children) were also available. Sixty-two percent of the participants were seropositive; corrected for the oversampling the estimated prevalence in the Amsterdam adult population was 61%. No specific predictors or risk groups for seropositivity were identified. In our urban adult study population no positive correlation with increasing neither age, nor significant differences between age groups were found. These results imply that almost 40% of the adult Amsterdam population is susceptible to infection. J. Med. Virol. 81:1305-1309, 2009. (c) 2009 Wiley-Liss, Inc.

Population-based study on the seroprevalence of hepatitis A, B, and C virus infection in Amsterdam, 2004.

In order to enhance screening and preventive strategies, this study investigated the seroprevalence of hepatitis A, B, and C in the general adult urban population and in subgroups. In 2004, sera from 1,364 adult residents of Amsterdam were tested for viral markers. Sociodemographic characteristics were collected using a standardized questionnaire. For hepatitis A, 57.0% was immune. Of first-generation immigrants from Turkey and Morocco, 100% was immune. Of all Western persons and second-generation non-Western immigrants, approximately half was still susceptible. For hepatitis B, 9.9% had antibodies to hepatitis B core antigen (anti-HBc) and 0.4% had hepatitis B surface antigen. Anti-HBc seroprevalences were highest among first-generation immigrants from Surinam, Morocco, and Turkey, and correlated with age at the time of immigration, and among men with a sexual preference for men. Seroprevalence among second-generation immigrants was comparable to Western persons. The seroprevalence of hepatitis C virus antibodies was 0.6%. In conclusion, a country with overall low endemicity for viral hepatitis can show higher endemicity in urban regions, indicating the need for differentiated regional studies and prevention strategies. More prevention efforts in cities like Amsterdam are warranted, particularly for hepatitis A and B among second-generation immigrants, for hepatitis B among men with a sexual preference for men, and for hepatitis C. Active case finding strategies are needed for both hepatitis B and C.

Effectiveness of a hepatitis A vaccination program for migrant children in Amsterdam, The Netherlands (1992-2004).

OBJECTIVE: To evaluate the impact and effectiveness of risk-group vaccination against hepatitis A targeted at migrant children living in a country with low endemicity of hepatitis A. METHODS: Retrospective population based data analysis. Routinely collected data on hepatitis A incidence in migrant children and other risk groups in Amsterdam from 1 January 1992 to 2004 were analyzed and related to exposure, immunity and vaccination coverage in migrant children. RESULTS: The overall hepatitis A incidence in Amsterdam declined after a pediatric vaccine was introduced in 1997. This decline was seen in migrant children traveling to hepatitis A-endemic countries, contacts with hepatitis A patients, primary school students, injecting drug users, and persons with unknown source of infection, but not in men who have sex with men (MSM) or in travelers to endemic countries other than migrant children. CONCLUSION: The hepatitis A vaccination campaigns are effective: they reduce both import and secondary HAV cases. The campaigns could be more efficient and cost-effective if the hepatitis B vaccinations currently given to these groups were replaced by a combined hepatitis A and B vaccine. This would increase the hepatitis A vaccination coverage considerably and further reduce the hepatitis A incidence.

[Post-exposure treatment against HIV outside of the hospital in Amsterdam, January-December 2000]. / Postexpositiebehandeling tegen HIV buiten het ziekenhuis in Amsterdam, januari-december 2000.

The Infectious Diseases Department of the Amsterdam Public Health Service regularly sees people who have possibly been exposed to human body fluids infected with hepatitis B virus (HBV), hepatitis C virus (HCV) or human immunodeficiency virus (HIV), as a result of incidents in either a non-hospital-related occupation or during their leisure time. Until January 2000, people reporting possible exposure were referred to hospitals for HIV post-exposure prophylaxis (HIV-PEP), whereas for HBV and HCV, the tracing of the infection source and the follow-up took place at the Public Health Service clinic. Since the introduction of a new protocol in January 2000, the Public Health Service as well as a hospital can establish an indication for HIV-PEP and prescribe it. In 2000, 322 persons reported to the Public Health Service. The source was tested in 194 incidents and an HIV test was carried out on 104 occasions. In 19 cases HIV antibodies were found or the source was known to be HIV positive. A total of 50 people were prescribed HIV-PEP; 16 times after a needle-stick accident, 22 times after a sexual accident, 6 times after a bite-wound and 6 times after direct exposure to human blood. The sources of 30 PEP recipients could be tested and after this 16 recipients could stop with the treatment due to a negative HIV test. In 4 cases PEP treatment was stopped following a review of the indication. Therefore, 30 people had an indication to complete the PEP treatment. Of these, more than 80% reported side effects and 3 people had to withdraw from the treatment at an early stage because of this. The implementation of the protocol has resulted in less confusion because the follow-up now takes place at one location. Compared to other studies, the average time between exposure and treatment is shorter and compliance is good. In the period up to 15 May 2001, no seroconversions had been observed.