Onno de Zwart

A cluster of acute hepatitis C virus infection among men who have sex with men : results from contact tracing and public health implications

Objective:An acute hepatitis C virus (HCV) infection in an HIV-positive man who had sex with men (MSM) was notified. In the period of his seroconversion he was also diagnosed with a rectal lymphogranuloma venereum (LGV) infection, and was part of a cluster of 15 LGV cases in 2003. Our aim was to investigate HCV transmission and to search for potential spread among sexual contacts and known LGV patients. Methods:Our case series included the index, two recent contacts, and 14 LGV cases. They were interviewed about parenteral exposure for HCV, history of sexually transmitted diseases(STDs), sexual behaviour and drug use. Laboratory investigations included anti-HCV antibodies, HCV-polymerase chain reaction, and HCV genotyping. Results:Seven out of 17 MSM recently seroconverted for HCV (41%). Three genotypes were found. Parenteral risk factors were excluded. Six out of seven had LGV proctitis coinciding with HCV seroconversion, six (86%) were HIV infected. Unprotected anal contact was practised by both HCV uninfected and infected cases. Unprotected active and passive fisting was reported by all seven HCV infected men, compared with two of nine uninfected men (P = 0.003). Non-intravenous drug use during sexual activities was common among all MSM. Numerous, often anonymous, sexual contacts in various European countries were reported. Conclusions:A cluster of acute HCV infection is reported among mostly HIV-positive MSM, with multiple partners throughout Europe. Sexual techniques potentially leading to mucosal damage (fisting), concomitant STDs such as LGV and drug use seem facilitating factors for spread. Extensive case finding and partner tracing is advocated as well as targeted prevention messages.

Precautionary Behavior in Response to Perceived Threat of Pandemic Influenza

Public transportation was regarded as the most risky place and home as the least risky.

A new meeting place: chatting on the Internet, e-dating and sexual risk behaviour among Dutch men who have sex with men.

Objective:To describe the process of Internet chatting, and subsequent dating and sexual (risk) behaviour among Dutch men who have sex with men (MSM), and to compare the demographic profile of the Internet sample with a traditional Dutch MSM sample. Design:A self-selected anonymous Internet sample. Methods:Enrolment via a prominent gay chat room. Potential respondents were asked to complete an online questionnaire about chatting and dating, and sexual (risk) behaviour with their last date via chatting (e-date). In 26 days, 5302 questionnaires were returned. Of these, 4984 were evaluated as reliable and were used in the analyses. Results:Eighty-two per cent chatted at least once a week, 88% had ever dated through chatting, and of these 89% had had sex with one or more e-dates. With respect to the last e-date, almost 50% had had anal sex with their last e-date, and 15% reported unprotected anal sex. Especially among HIV-positive men, a high percentage of unprotected anal sex was reported (39%). After correcting for the disclosure of HIV status, this percentage remained twice as high compared with HIV-negative and never-tested men (28 versus 14%). Compared with a traditional MSM sample, the Internet sample was significantly younger, and comprised more non-Dutch and bisexual men, whereas the level of sexual risk behaviour with casual partners was comparable. Conclusion:The Internet is a popular new meeting place for MSM, and attracts men with a different demographic profile. The level of risk behaviour warrants that opportunities for interventions on the Internet are explored, with special attention to HIV-positive chatters.

Perceived risk, anxiety, and behavioural responses of the general public during the early phase of the Influenza A (H1N1) pandemic in the Netherlands: Results of three consecutive online surveys

BackgroundResearch into risk perception and behavioural responses in case of emerging infectious diseases is still relatively new. The aim of this study was to examine perceptions and behaviours of the general public during the early phase of the Influenza A (H1N1) pandemic in the Netherlands.MethodsTwo cross-sectional and one follow-up online survey (survey 1, 30 April-4 May; survey 2, 15-19 June; survey 3, 11-20 August 2009). Adults aged 18 years and above participating in a representative Internet panel were invited (survey 1, n = 456; survey 2, n = 478; follow-up survey 3, n = 934). Main outcome measures were 1) time trends in risk perception, feelings of anxiety, and behavioural responses (survey 1-3) and 2) factors associated with taking preventive measures and strong intention to comply with government-advised preventive measures in the future (survey 3).ResultsBetween May and August 2009, the level of knowledge regarding Influenza A (H1N1) increased, while perceived severity of the new flu, perceived self-efficacy, and intention to comply with preventive measures decreased. The perceived reliability of information from the government decreased from May to August (62% versus 45%). Feelings of anxiety decreased from May to June, and remained stable afterwards. From June to August 2009, perceived vulnerability increased and more respondents took preventive measures (14% versus 38%). Taking preventive measures was associated with no children in the household, high anxiety, high self-efficacy, more agreement with statements on avoidance, and paying much attention to media information regarding Influenza A (H1N1). Having a strong intention to comply with government-advised preventive measures in the future was associated with higher age, high perceived severity, high anxiety, high perceived efficacy of measures, high self-efficacy, and finding governmental information to be reliable.ConclusionsDecreasing trends over time in perceived severity and anxiety are consistent with the reality: the clinical picture of influenza turned out to be mild in course of time. Although (inter)national health authorities initially overestimated the case fatality rate, the public stayed calm and remained to have a relatively high intention to comply with preventive measures.

Avian influenza risk perception, Europe and Asia.

During autumn 2005, we conducted 3,436 interviews in European and Asian countries. We found risk perceptions of avian influenza to be at an intermediate level and beliefs of efficacy to be slightly lower. Risk perceptions were higher in Asia than Europe; efficacy beliefs were lower in Europe than Asia.

SARS Risk Perception, Knowledge, Precautions, and Information Sources, the Netherlands

Severe acute respiratory syndrome (SARS)–related risk perceptions, knowledge, precautionary actions, and information sources were studied in the Netherlands during the 2003 SARS outbreak. Although respondents were highly aware of the SARS outbreak, the outbreak did not result in unnecessary precautionary actions or fears.

Perceived threat, risk perception, and efficacy beliefs related to SARS and other (emerging) infectious diseases: Results of an international survey

PurposeTo study the levels of perceived threat, perceived severity, perceived vulnerability, response efficacy, and self-efficacy for severe acute respiratory syndrome (SARS) and eight other diseases in five European and three Asian countries.MethodA computer-assisted phone survey was conducted among 3,436 respondents. The questionnaire focused on perceived threat, vulnerability, severity, response efficacy, and self-efficacy related to SARS and eight other diseases.ResultsPerceived threat of SARS in case of an outbreak in the country was higher than that of other diseases. Perceived vulnerability of SARS was at an intermediate level and perceived severity was high compared to other diseases. Perceived threat for SARS varied between countries in Europe and Asia with a higher perceived severity of SARS in Europe and a higher perceived vulnerability in Asia. Response efficacy and self-efficacy for SARS were higher in Asia compared to Europe. In multiple linear regression analyses, country was strongly associated with perceived threat.ConclusionsThe relatively high perceived threat for SARS indicates that it is seen as a public health risk and offers a basis for communication in case of an outbreak. The strong association between perceived threat and country and different regional patterns require further research.

Sources of information and health beliefs related to SARS and avian influenza among Chinese Communities in the United Kingdom and the Netherlands, compared to the general population in these countries

BackgroundEthnic minorities in Europe such as the Chinese may need a special strategy with regard to risk communication about emerging infectious diseases. To engage them in precautionary actions, it is important to know their information sources, knowledge, and health beliefs.PurposeThis study’s purpose is to study the use of information sources, knowledge, and health beliefs related to SARS and avian flu of Chinese people in the UK and The Netherlands, and to make comparisons with the general population in these countries.MethodResults of a self-administered questionnaire among 300 British/Dutch Chinese were compared to data obtained from a computer-assisted phone survey among the general population (n = 800).ResultsBritish/Dutch Chinese got most information about emerging diseases from family and friends, followed by Chinese media and British/Dutch TV. They had less confidence than general groups in their doctor, government agencies, and consumer/patient interest groups. Their knowledge of SARS was high. They had a lower perceived threat than general populations with regard to SARS and avian flu due to a lower perceived severity. They had higher self-efficacy beliefs regarding SARS and avian flu.ConclusionIn case of new outbreaks of SARS/avian flu in China, local authorities in the UK and The Netherlands can best reach Chinese people through informal networks and British/Dutch TV, while trying to improve confidence in information from the government. In communications, the severity of the disease rather than the susceptibility appears to need most attention.

Viral hepatitis in a multi-ethnic neighborhood in the Netherlands: results of a community-based study in a low prevalence country

OBJECTIVES The prevalence of viral hepatitis varies worldwide. Although the prevalence of hepatitis A virus (HAV) and hepatitis B virus (HBV) infection is generally low in Western countries, pockets of higher prevalence may exist in areas with large immigrant populations. The aim of this study was to obtain further information on the prevalence of viral hepatitis in a multi-ethnic area in the Netherlands. METHODS We conducted a community-based study in a multi-ethnic neighborhood in the city of Rotterdam, the Netherlands, including both native Dutch and migrant participants, who were tested for serological markers of hepatitis A, hepatitis B, and hepatitis C infection. RESULTS Markers for hepatitis A infection were present in 68% of participants. The prevalence of hepatitis B core antibodies (anti-HBc), a marker for previous or current infection, was 20% (58/284). Prevalence of hepatitis A and B varied by age group and ethnicity. Two respondents (0.7%) had chronic HBV infection. The prevalence of hepatitis C was 1.1% (3/271). High levels of isolated anti-HBc were found. CONCLUSIONS We found a high prevalence of (previous) viral hepatitis infections. This confirms previous observations in ethnic subgroups from a national general population study and illustrates the high burden of viral hepatitis in areas with large immigrant populations.

Identification and treatment of chronic hepatitis B in Chinese migrants: Results of a project offering on-site testing in Rotterdam, the Netherlands

BACKGROUND & AIMS Migrants born in countries where hepatitis B is endemic are a risk group for chronic hepatitis B virus (HBV) infection. Treatment options have improved, but due to the asymptomatic nature of chronic HBV infection, the majority of patients remain unidentified. METHODS In 2009, a campaign targeting the Chinese community was held in the city of Rotterdam, The Netherlands. The campaign combined disease awareness activities with free HBV testing at outreach locations. Chronically HBV infected patients were referred to specialist care based on a referral guideline. Before and after the campaign, knowledge of chronic hepatitis B was measured through questionnaires in a convenience sample of the target population (n=285 and n=277). RESULTS In a period of 3 months, 13 outreach activities took place and 1090 Chinese migrants were tested for HBV. Forty-nine percent had serological signs of a past or recent HBV infection and 8.5% (n=92) were chronically infected. Thirty-eight percent (n=35) of chronically infected patients were referred for evaluation by a specialist and of these, 15 started antiviral treatment within 1 year of follow-up. Before the campaign, 55% answered correctly to 6 or more out of 10 knowledge items. Knowledge was positively associated with educational level. After the campaign, an increase in knowledge was observed in participants with low levels of education. CONCLUSIONS Chinese migrants could be reached with an outreach campaign, and on-site testing was well accepted. A high prevalence of chronic HBV infection was found and referral to specialist care and initiation of treatment was successful.