http://repub.eur.nl/res/aut/15553/ List of Publications en http://repub.eur.nl/static-eur/img/logo.png http://repub.eur.nl http://repub.eur.nl/res/pub/20272/ 2010-08-08T00:00:00Z BACKGROUND: Avian influenza (AI) is a public health challenge because of ongoing spread and pandemic potential. Non-pharmaceutical measures are important to prevent the spread of AI and to contain a pandemic. The effectiveness of such measures is largely dependent on the behaviour of the population. Risk perception is a central element in changing behaviour. This study aimed to investigate perceived vulnerability, severity and precautionary behaviour related to AI in the Netherlands during seven consecutive surveys in 2006 - 2007 as well as possible trends in risk perception and self-reported precautionary behaviours. METHODS: Seven web-based surveys were conducted including 3,840 respondents over a one-year period. Time trends were analyzed with linear regression analyses. Multivariate analysis was used to study determinants of precautionary behaviour. RESULTS: While infection with AI was considered a very severe health problem with mean score of 4.57 (scale 1 - 5); perceived vulnerability was much lower, with a mean score of 1.69. While perceived severity remained high, perceived vulnerability decreased slightly during a one-year period covering part of 2006 and 2007. Almost half of the respondents (46%) reported taking one or more preventive measures, with 36% reporting to have stayed away from (wild) birds or poultry. In multivariate logistic regression analysis the following factors were significantly associated with taking preventive measures: time of the survey, higher age, lower level of education, non-Dutch ethnicity, vaccinated against influenza, higher perceived severity, higher perceived vulnerability, higher self efficacy, lower level of knowledge, more information about AI, and thinking more about AI. Self efficacy was a stronger predictor of precautionary behaviour for those who never or seldom think about AI (OR 2.3, 95% CI 1.9 - 2.7), compared to those who think about AI more often (OR 1.5, 95% CI 1.2 - 1.9). CONCLUSIONS: The fact that perceived severity of AI appears to be high and remains so over time offers a good point of departure for more specific risk communications to promote precautionary actions. Such communications should aim at improving knowledge about the disease and preventive actions, and focus on perceived personal vulnerability and self efficacy in taking preventive measures. http://repub.eur.nl/res/pub/17432/ 2009-09-04T00:00:00Z People with chronic hepatitis B virus infection remain infectious to others and are at risk of serious liver disease such as liver cirrhosis or liver cancer later in life. In the Netherlands, hepatitis B is low endemic and acute infections are mainly transmitted through sexual contact. Chronic infections are found mostly in migrants born in countries where hepatitis B is relatively prevalent. Primary prevention of hepatitis B is possible through vaccination, but vaccination does not have an impact on pre-existing chronic infections. Screening for hepatitis B is a form of secondary prevention, whereby antiviral treatment can be used to prevent the occurrence of hepatitis B related liver disease. As the possibilities of antiviral therapy to prevent liver disease caused by chronic hepatitis B have greatly improved, it becomes more important to identify chronic hepatitis B patients. In this thesis, the following research questions are addressed: 1) What are the! transmission routes, sources of infection and risk factors for acute hepatitis B virus infection in the Netherlands?; 2) What is the prevalence of hepatitis B virus infection in different ethnic groups in Rotterdam?; 3) What is the added value of molecular analysis in hepatitis B source and contact tracing?; 4) What is the impact of secondary prevention of hepatitis B? We conclude that to increase access to antiviral treatment for patients with active chronic hepatitis B, the detection of chronic hepatitis B patients should be improved. To do so, a proactive approach is necessary as most patients do not have symptoms. http://repub.eur.nl/res/pub/16057/ 2009-06-02T00:00:00Z In November 2002, the Netherlands adopted a vaccination program targeted at behavioural risk groups. Between January 2003 and December 2007, 1386 patients acutely infected with HBV were reported. Reported cases declined from 326 in 2003 to 220 in 2007. Sexual intercourse was the most frequently reported mode of transmission (65%), especially among men having sex with men. Genotypes A and D remained predominant. In total, 40,600 participants were fully vaccinated, the overall compliance was 62%, and the estimated overall program coverage was 12% of the at-risk population. With more effort, more susceptibles may be reached, but the program will not be sufficient to substantially reduce HBV in the Netherlands. Therefore, universal vaccination should be considered. http://repub.eur.nl/res/pub/18233/ 2009-03-01T00:00:00Z Background: Ethnic 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. Purpose: This 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. Method: Results 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). Results: British/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. Conclusion: In 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. http://repub.eur.nl/res/pub/18234/ 2009-03-01T00:00:00Z Background: Although the SARS outbreak involved few probable cases of infection in Europe, swift international spread of infections raised the possibility of outbreaks. In particular, SARS presented a sociopsychological and economic threat to European Chinese communities because of their close links with the outbreak's origins. Methods: A qualitative study was conducted among Chinese residents in the United Kingdom and the Netherlands to identify the origins of SARS risk perceptions and their impact on precautionary actions and adverse consequences from the perspective of vulnerable communities living in unaffected regions. Analysis was informed by protection motivation theory. Results: Results revealed that information from affected Asia influenced risk perceptions and protective behavior among the Chinese in Europe when more relevant local information was absent. When high risk perceptions were combined with low efficacy regarding precautionary measures, avoidance-based precautionary action appeared to dominate responses to SARS. These actions may have contributed to the adverse impacts of SARS on the communities. Conclusions: Experiences of European Chinese communities suggest that practical and timely information, and consistent implementation of protective measures from central governments are essential to protect vulnerable populations in unaffected regions from unnecessary alarm and harm during outbreaks of emerging infections. http://repub.eur.nl/res/pub/18236/ 2009-03-01T00:00:00Z Purpose: To 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. Method: A 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. Results: Perceived 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. Conclusions: The 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. http://repub.eur.nl/res/pub/13662/ 2005-02-01T00:00:00Z BACKGROUND: Screening for Chlamydia trachomatis infections is aimed at the reduction of these infections and subsequent complications. Selective screening may increase the cost effectiveness of a screening programme. Few population based systematic screening programmes have been carried out and attempts to validate selective screening criteria have shown poor performance. This study describes the development of a prediction rule for estimating the risk of chlamydial infection as a basis for selective screening. METHODS: A population based chlamydia screening study was performed in the Netherlands by inviting 21,000 15-29 year old women and men in urban and rural areas for home based urine testing. Multivariable logistic regression was used to identify risk factors for chlamydial infection among 6303 sexually active participants, and the discriminative ability was measured by the area under the receiver operating characteristic curve (AUC). Internal validity was assessed with bootstrap resampling techniques. RESULTS: The prevalence of C trachomatis (CT) infection was 2.6% (95% CI 2.2 to 3.2) in women and 2.0% (95% CI 1.4 to 2.7) in men. Chlamydial infection was associated with high level of urbanisation, young age, Surinam/Antillian ethnicity, low/intermediate education, multiple lifetime partners, a new contact in the previous two months, no condom use at last sexual contact, and complaints of (post)coital bleeding in women and frequent urination in men. A prediction model with these risk factors showed adequate discriminative ability at internal validation (AUC 0.78). CONCLUSION: The prediction rule has the potential to guide individuals in their choice of participation when offered chlamydia screening and is a promising tool for selective CT screening at population level.