Wellness centres: an important but overlooked source of Legionnaires disease. Eight years of source investigation in the Netherlands, 1 August 2002 to 1 August 2010.

Visiting wellness centres is considered safe and relaxing and might provide health benefits for visitors with certain cardiovascular, dermatological or respiratory diseases. On the other hand, wellness centres could pose health risks, especially with respect to Legionnaires' disease. We investigated the role of wellness centres in the occurrence of Legionnaires' disease by analysing the data of eight years (2002­2010) of source investigation in the Netherlands. There were 15 wellness centres identified as potential sources of infection for a total of 35 Legionnaires' disease patients. Twelve of these centres were positive for Legionella spp.: six for Legionella pneumophila, six for non-pneumophila Legionella spp.. Of the 65 positive environmental samples found during the wellness centre investigations, 41 were derived from shower heads. For two centres, the Legionella pneumophila strains in the collected samples had a genotype that was indistinguishable from the patient isolates. These results show that wellness centres are potential sources of Legionnaires' disease.

Outbreak investigation in two groups of coach passengers with gastroenteritis returning from Germany to the Netherlands in February 2009.

In February 2009, an outbreak of 38 cases of gastroenteritis occurred among the participants of two Dutch coach trips (A and B) who visited the same hotel in Germany. We initiated an outbreak investigation to determine possible risk of food-borne infection. A retrospective cohort study was performed among 87 passengers using a self-administered questionnaire. The response rate was 75 of 87 (86%). Mean age was 65 years. Cases were defined as participants of the two coach trips who had diarrhoea and/or vomiting at least once within 24 hours in the period between 7 and 14 February 2009. We distinguished early and late cases, with symptoms starting within or after 72 hours of arrival in the hotel. Overall attack-rate was 38 of 75 (51%). Microbiological investigation was performed on stool samples of two passengers from Coach A and two passengers from Coach B. Identical norovirus genotype II.4 sequences were detected in all four samples. Univariate analysis revealed a potential risk for early cases from juice consumption , which was most clearly seen for Coach B on day of arrival (juice at lunch: relative risk (RR): 3.9, 95% confidence interval (CI): 1.3-11.7; juice at dinner: RR: 5.5, 95% CI: 1.6-18.1). A dose-response relationship was found. This outbreak was probably caused by using the taps of juice served in large containers with a tap for self-service, due to environmental contamination through person-to-person transmission. Still the role of either contaminated juice or contact with contaminated juice cannot be ruled out.

[Increase of early syphilis in Rotterdam (1995-1997): more (addicted) prostitutes and their clients]. / Toename van vroege syfilis in Rotterdam (1995-1997): meer (verslaafde) prostituees en hun bezoekers.

OBJECTIVE: To detect risk groups in an increase of early (infectious) syphilis. DESIGN: Retrospective study of patient records. METHOD: Data from visitors with an early syphilis were collected from their respective medical records in the outpatient clinic for sexually transmitted diseases (STD) of the Academic Hospital Rotterdam-Dijkzigt, the Netherlands, over the years 1993-1997. In particular, data on risk behaviour and risk groups were collected. To obtain an indication of the (possible) causes of the increase in the number of visitors with early syphilis, (shifts in) characteristics of this population over the years were compared. RESULTS: 195 patients with early syphilis had visited the outpatient clinic, 130 males and 65 females, mean ages ranging from 30.9 (1993) to 38.1 years (1997). Most infected persons (68%) came to the outpatient clinic because of symptoms. The number of women who came to the outpatient clinic through partner notification increased considerably, from an average of 5% in 1993-1995 to 36% in 1996. Over the years a relative increase of (drug addicted) prostitutes and their clients was observed (1993-1995: 39%; 1996: 56%). CONCLUSION: The cause of the increase, or failure to decrease, of the number of syphilis-infected visitors in the STD outpatient clinic of the Academic Hospital Rotterdam-Dijkzigt should probably be sought among (drug addicted) prostitutes and their visitors.

[Increase of early syphilis in a red light district in Rotterdam (1995-1997) and preventive treatment]. / Toename van vroege syfilis in een tippelzone in Rotterdam (1995-1997) en profylactische behandeling.

The number of cases of syphilis in Rotterdam has increased dramatically since 1995. The prevalence of early syphilis in 1997 was highest among street prostitutes (16%). Some prostitutes could not be reached for further evaluation and treatment, probably due to their addiction to hard drugs. Prophylactic treatment for syphilis was given to most street prostitutes in a cruising zone during a screening programme for sexually transmitted diseases (STD) in January 1997. Since then, STD checkups were performed regularly in the cruising zone. The prevalence of early syphilis in the cruising zone dropped to 1.3% in 1998. The total number of reported cases of syphilis in Rotterdam also decreased sharply in 1998.

Reaching homosexual men for HIV surveillance through a gay magazine.

HIV surveillance in homosexual men is poor in most countries, as this risk group is difficult to sample. The aim of this study is to test the feasibility of reaching homosexual men for national HIV surveillance using gay community media. In 1989, a questionnaire on general gay issues, with a section on AIDS, was included in a widely sold gay magazine in the Netherlands. Among 17,700 sold copies, 1134 responses were obtained from males (6%). Of these, 669 men (59%) gave their address, of which in turn 84% responded to a questionnaire on risk behaviour in 1990. In 1991/1992, the 669 men were asked to participate in an HIV serosurvey, in which eventually 308 participated with a blood test (46%) and 147 without (total 68%). Participation in the serosurvey with blood test was associated with reporting multiple partners in 1989. Twenty participants were infected (6.5%). In logistic regression analysis, risk factors for infection were recent unprotected receptive anal intercourse with multiple partners (odds ratio (OR): 10.7; 95% confidence interval (CI): (2.18-52.2); one partner 1.17 (0.31-4.48); none 1) and living in Amsterdam (OR: 3.92; 95% CI: (0.99-15.5); urbanised western Netherlands 2.15 (0.57-8.03); elsewhere 1), while a high educational level was protective (OR: 0.29 (0.08-0.96); middle 0.41 (0.11-1.54); low 1). Among those who participated in 1991/1992, risk behaviour increased between 1989 and 1991/1992 (reporting multiple casual partners rose from 55% to 64%; reporting inconsistent condom use with receptive anal sex from 58% to 71%). Using a predictive model which included self-reported serostatus in 1989, the HIV prevalence rate in 1991/1992 among all male responders to the 1989 questionnaire was estimated to be 5.3% (95% CI: 3.1 7.7%). In conclusion, unless initial response is improved, recruitment through a gay magazine may not allow reliable estimates of HIV prevalence in homosexual men. However, it can be useful at the national level for monitoring changes in prevalence and risk behaviour over time, geographical differences and risk factors for infection.

Patient referral outcome in gonorrhoea and chlamydial infections.

OBJECTIVE: To describe the outcome of patient referral at the STD clinic of the University Hospital Rotterdam. To study characteristics of heterosexual index patients and partnerships related to referral outcome. METHODS: In 1994, patients with gonorrhoea and chlamydia were referred to public health nurses for interview and patient referral. Referral outcome was classified as "verified" if partners attended the STD clinic and as "believed" if partners were said to have attended elsewhere. RESULTS: Of 454 patients, 250 (55%) participated in the study. The outcome of patient referral for the 502 eligible partners was 103 (20.5%) verified referrals, 102 (20%) believed referrals, and 297 (59%) with unknown follow up. Of the 103 partners examined, 43 had an STD of which 63% reported no symptoms. The contact finding ratio was higher for chlamydia patients and heterosexual men. Also, referral was more effective for index patients with recent sexual contact, with follow up visits to the public health nurse, for men who were not commercial sex worker (CSW) clients, and, to a lesser degree, for Dutch patients and patients who sometimes used condoms. For steady partners, referral was improved if the last sexual contact was more recent. Casual partners visited the clinic more often if sexual contact occurred more than once, if the last contact was more recent, if they were older, and if they were Dutch. CONCLUSIONS: Patient referral was more effective for certain groups, such as chlamydia patients and steady partners, but was inadequate for others, including CSW and their clients, other "one night stands", young partners, and ethnic minorities.

Prevalence and risk factors for hepatitis B virus infections among visitors to an STD clinic.

OBJECTIVE: To determine the prevalence and risk factors for hepatitis B virus (HBV) infections among individuals attending an STD clinic in a low endemic region. STUDY DESIGN: A total of 1228 women and 1648 men attending the STD clinic at the University Hospital Rotterdam, Netherlands, were examined for HBV infection by determination of hepatitis B surface antigen (HBsAg) and antibodies to hepatitis B core antigen (anti-HBc). Demographic characteristics, information on sexual behaviour, and intravenous drug use were recorded. RESULTS: The seroprevalence of HBsAg was 1.4% in women and 2.1% in men (0% in homosexual men). The seroprevalence of anti-HBc was 13% in women and 20% in men (36% in homosexual men). Native country, intravenous drug use, a history of STD, and the number of partners in the past half year (inversely) were independent risk factors for HBsAg positivity in women and heterosexual men. For anti-HBc independent associations were observed for native country, age, intravenous drug use, commercial sex, number of lifetime partners, homosexual contacts, orogenital contact (inverse), and a history of STD. CONCLUSION: The HBV prevalence in the STD clinic attendants was high, exceeding the national estimate, and indicates that the STD clinic population may be considered a high risk group. Our data confirmed an increased risk for HBV infections among established risk groups. Therefore, these risk groups should be routinely screened to identify HBV cases for counselling and contact tracing.

Different demographic and sexual correlates for chlamydial infection and gonorrhoea in Rotterdam.

BACKGROUND: The objective of the study was to estimate the prevalence of gonorrhoea and chlamydial infections and to determine sexual and demographic correlates for these sexually transmitted diseases (STD) among visitors of an STD clinic. METHODS: In 1994, a cross-sectional study was carried out among 2984 consecutive visitors of the STD clinic of the University Hospital Rotterdam. RESULTS: The prevalence of chlamydial infection was 12.1% for women and 12.3% for men. For gonorrhoea, prevalence was 3.2% and 6.0%, respectively. For men, gonorrhoea was independently associated with multiple partners in the last month, homosexual activities, a history of gonorrhoea, last sexual contact in the past 4-14 days and casual partners. In contrast, chlamydial infection was less likely to be found in homosexual men and male intravenous drug users. Additionally, chlamydial infection was independently associated with young age, multiple partners in the last 6 months and with last sexual contact in the past 2 months. For women, intravenous drug use (associated with commercial sex work) and a history of trichomoniasis were independent risk factors for gonorrhoea. Independent risk factors for chlamydial infection in women were: young age, two or three sexual partners during life and last sexual contact within 2 months. Chlamydial infection was uncommon in commercial sex workers. CONCLUSIONS: The differences in the epidemiological correlates suggest that chlamydial infection is more diffusely spread into the general population than gonorrhoea. Additionally, it is hypothesized that men acquire their chlamydial infection through less stable relationships and subsequently infect their regular female partner.

Differences in perception of risk for HIV infection with steady and non-steady partners among homosexual men.

In this study it was assessed whether homosexual men who practiced unprotected anogenital intercourse with steady and non-steady partners subjectively perceived their behaviors to be risky. Data were collected from 165 homosexual participants in an ongoing cohort study who reported unprotected anal sex. A variety of psychological factors which could possibly explain why some men were at risk but did not perceive their behavior as such, were investigated. This study showed that the majority of men who engaged in sexual risk behaviors within their primary relationship did not subjectively appraise their behavior as risky. The factors found to explain this discrepancy were not having had sex with a partner known to be HIV infected or to have AIDS (for couples of unknown serostatus) and not having had friends or relatives who were ill or had died (for seronegative couples). Homosexual men who had unprotected anal sex with casual partners generally were aware of the risk involved in their behavior.