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Background During the course of an influenza pandemic, governments know relatively little about the possibly changing influence of government trust, risk perception, and receipt of information on the public's intention to adopt protective measures or on the acceptance of vaccination. This study aims to identify and describe possible changes in and factors associated with public's intentions during the 2009 influenza A (H1N1) pandemic in the Netherlands. Methods Sixteen cross-sectional telephone surveys were conducted (N = 8060) between April - November 2009. From these repeated measurements three consecutive periods were categorized based on crucial events during the influenza A (H1N1) pandemic. Time trends in government trust, risk perception, intention to adopt protective measures, and the acceptance of vaccination were analysed. Factors associated with an intention to adopt protective measures or vaccination were identified. Results Trust in the government was high, but decreased over time. During the course of the pandemic, perceived vulnerability and an intention to adopt protective measures increased. Trust and vulnerability were associated with an intention to adopt protective measures in general only during period one. Higher levels of intention to receive vaccination were associated with increased government trust, fear/worry, and perceived vulnerability. In periods two and three receipt of information was positively associated with an intention to adopt protective measures. Most respondents wanted to receive information about infection prevention from municipal health services, health care providers, and the media. Conclusions The Dutch response to the H1N1 virus was relatively muted. Higher levels of trust in the government, fear/worry, and perceived vulnerability were all positively related to an intention to accept vaccination. Only fear/worry was positively linked to an intention to adopt protective measures during the entire pandemic. Risk and crisis communication by the government should focus on building and maintaining trust by providing information about preventing infection in close collaboration with municipal health services, health care providers, and the media.

Background Research 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. Methods Two 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). Results Between 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. Conclusions Decreasing 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.

The essential guide to controlling and managing today's communicable diseases The fourth edition of Communicable Disease Control and Health Protection Handbook offers public health workers of all kinds an authoritative and up-to-date guide to current protocols surrounding the identification and control of infectious diseases. With its concise, accessible design, the book is a practical tool that can be relied upon to explain topics ranging from the basic principles of communicable disease control to recent changes and innovations in health protection practice. Major syndromes and individual infections are insightfully addressed, while the authors also outline the WHO's international health regulations and the organizational arrangements in place in all EU nations. New to the fourth edition are chapters on Ebola, the Zika virus, and other emerging pandemics. In addition, new writing on healthcare-associated infection, migrant and refugee health, and the importance of preparedness make this an essential and relevant text for all those in the field. This vital resource: * Reflects recent developments in the science and administration of health protection practice * Covers topics such as major syndromes, control of individual infections, main services and activities, arrangements for all European countries, and much more * Includes new chapters on the Zika virus, Schistosomiasis, Coronavirus including MERS + SARS, and Ebola * Follows a format designed for ease of use and everyday consultation Created to provide public and environmental health practitioners, physicians, epidemiologists, infection control nurses, microbiologists and trainees with a straightforward – yet informative – resource, Communicable Disease Control and Health Protection Handbook is a practical companion for all those working the field today.

Information on social interactions is needed to understand the spread of airborne infections through a population. Previous studies mostly collected egocentric information of independent respondents with self-reported information about contacts. Respondent-driven sampling (RDS) is a sampling technique allowing respondents to recruit contacts from their social network. We explored the feasibility of webRDS for studying contact patterns relevant for the spread of respiratory pathogens. We developed a webRDS system for facilitating and tracking recruitment by Facebook and email. One-day diary surveys were conducted by applying webRDS among a convenience sample of Thai students. Students were asked to record numbers of contacts at different settings and self-reported influenza-like-illness symptoms, and to recruit four contacts whom they had met in the previous week. Contacts were asked to do the same to create a network tree of socially connected individuals. Correlations between linked individuals were analysed to investigate assortativity within networks. We reached up to 6 waves of contacts of initial respondents, using only non-material incentives. Forty-four (23.0%) of the initially approached students recruited one or more contacts. In total 257 persons participated, of which 168 (65.4%) were recruited by others. Facebook was the most popular recruitment option (45.1%). Strong assortative mixing was seen by age, gender and education, indicating a tendency of respondents to connect to contacts with similar characteristics. Random mixing was seen by reported number of daily contacts. Despite methodological challenges (e.g. clustering among respondents and their contacts), applying RDS provides new insights in mixing patterns relevant for close-contact infections in real-world networks. Such information increases our knowledge of the transmission of respiratory infections within populations and can be used to improve existing modelling approaches. It is worthwhile to further develop and explore webRDS for the detection of clusters of respiratory symptoms in social networks.

Understanding infection dynamics of respiratory diseases requires the identification and quantification of behavioural, social and environmental factors that permit the transmission of these infections between humans. Little empirical information is available about contact patterns within real-world social networks, let alone on differences in these contact networks between populations that differ considerably on a socio-cultural level. Here we compared contact network data that were collected in The Netherlands and Thailand using a similar online respondent-driven method. By asking participants to recruit contact persons we studied network links relevant for the transmission of respiratory infections. We studied correlations between recruiter and recruited contacts to investigate mixing patterns in the observed social network components. In both countries, mixing patterns were assortative by demographic variables and random by total numbers of contacts. However, in Thailand participants reported overall more contacts which resulted in higher effective contact rates. Our findings provide new insights on numbers of contacts and mixing patterns in two different populations. These data could be used to improve parameterisation of mathematical models used to design control strategies. Although the spread of infections through populations depends on more factors, found similarities suggest that spread may be similar in The Netherlands and Thailand.

Respondent-driven detection is a chain recruitment method used to sample contact persons of infected persons in order to enhance case finding. It starts with initial individuals, so-called seeds, who are invited for participation. Afterwards, seeds receive a fixed number of coupons to invite individuals with whom they had contact during a specific time period. Recruitees are then asked to do the same, resulting in successive waves of contact persons who are connected in one recruitment tree. However, often the majority of participants fail to invite others, or invitees do not accept an invitation, and recruitment stops after several waves. A mathematical model can help to analyse how various factors influence peer recruitment and to understand under which circumstances sustainable recruitment is possible. We implemented a stochastic simulation model, where parameters were suggested by empirical data from an online survey, to determine the thresholds for obtaining large recruitment trees and the number of waves needed to reach a steady state in the sample composition for individual characteristics. We also examined the relationship between mean and variance of the number of invitations sent out by participants and the probability of obtaining a large recruitment tree. Our main finding is that a situation where participants send out any number of coupons between one and the maximum number is more effective in reaching large recruitment trees, compared to a situation where the majority of participants does not send out any invitations and a smaller group sends out the maximum number of invitations. The presented model is a helpful tool that can assist public health professionals in preparing research and contact tracing using online respondent-driven detection. In particular, it can provide information on the required minimum number of successfully sent invitations to reach large recruitment trees, a certain sample composition or certain number of waves.

During the 2009 influenza A (H1N1) pandemic, parents in the Netherlands were recommended to vaccinate healthy children between six months and five years of age. The aim of this study was to examine reasons for (non-)acceptance, risk perception, feelings of doubt and regret, influence of the social network, and information-seeking behavior of parents who accepted or declined H1N1 vaccination. Data on accepters were collected via exit interviews following the second-dose vaccination round in December 2009 (n=1227). Data on decliners were gathered in June and July 2010 with questionnaires (n=1900); 25 parents participated in in-depth interviews. The most reported reasons for parental acceptance of H1N1 vaccination were “I don’t want my child to become sick” (43%), “Mexican flu can be severe” (10%), “the government advises it, so I do it” (6%), and “if I don’t do it, I will regret it” (6%). The most reported reasons declining the vaccination were “fear of side effects/harmful consequences” (51%), “just having a bad feeling about it” (46%), and “the vaccine was not thoroughly tested” (39%). More decliners than accepters experienced feelings of doubt about the vaccination decision (decliners 63% versus accepters 51%, p<0.001), and decliners reported more often information-seeking behavior (decliners 76% versus accepters 56%, p<0.001). Decliners more frequently solicited advice from their social network than accepters (decliners 72% versus accepters 61%, p<0.001). Furthermore, accepters more often reported social influence on their vaccination decision (accepters 58% versus decliners 38%, p<0.001) and experienced more negative feelings after their vaccination decision (accepters 8% versus decliners 2%, p<0.001). Immigrant accepters and decliners more often had feelings of doubt and regret about the vaccination decision, solicited advice more often from their social network, and were more often influenced by this advice compared to native Dutch parents. To optimize response rates in future vaccination campaigns, health authorities should provide more information on vaccine benefits and possible risks, tailoring this information to specific risk groups. Health authorities should also invest in the development and implementation of effective vaccine risk/benefit communication tools.

Travelers can experience health problems while abroad. This descriptive study aimed to quantify the disease burden leading to hospital-based care, repatriation or death in Dutch travelers during a stay in a foreign country, including Europe. Retrospective study of demographic and clinical data from three medical assistance centers (MACs) and the Dutch Ministry of Foreign Affairs on Dutch travelers receiving hospital-based care or who died abroad in the years 2010–2014. Diagnoses were coded according to the International Classification of Diseases (ICD) and classified using the Global Burden of Disease tool. Data was available for 77,741 travelers’ incidents: 75,385 medical consultations and 2,356 deaths. Four in five travelers received inpatient care, of which 36% concerned older travelers (65+) who had significantly longer hospital stays. Overall the top three diagnoses were: injuries (29%), infectious diseases (17%), and cardiovascular diseases (17%). Mental illness was reported in nearly 1.5% of the travelers. Incidence proportions were highest in South-Eastern Asia, with enteric infections as most common diagnosis. Injuries and communicable diseases occurred most often in South-Eastern Asia, while non-communicable diseases were mostly reported in South America. One in five travelers who consulted a physician was repatriated back home, mostly on a scheduled flight with or without medical escort. Cardiovascular diseases and injuries were the leading causes of death. Not only communicable diseases, but also injuries and chronic diseases (in particular cardiovascular diseases) frequently affected travelers’ health while staying abroad and frequently necessitated hospital-based care. This should be addressed during the pre-travel counseling.

Background In November 2016, the Dutch Health Council recommended hepatitis B (HBV) screening for first-generation immigrants from HBV endemic countries. However, these communities show relatively low attendance rates for screening programmes, and our knowledge on their participation behaviour is limited. We identified determinants associated with the intention to request an HBV screening test in first-generation Moroccan-Dutch immigrants. We also investigated the influence of non-refundable costs for HBV screening on their intention. Methods Offline and online questionnaires were distributed among first- and second/third-generation Moroccan-Dutch immigrants using respondent-driven sampling. Random forest analyses were conducted to determine which determinants had the greatest impact on (1) the intention to request an HBV screening test on one’s own initiative, and (2) the intention to participate in non-refundable HBV screening at €70,-. Results Of the 379 Moroccan-Dutch respondents, 49.3% intended to request a test on their own initiative, and 44.1% were willing to attend non-refundable screening for €70,-. Clarity regarding infection status, not having symptoms, fatalism, perceived self-efficacy, and perceived risk of having HBV were the strongest predictors to request a test. Shame and stigma, fatalism, perceived burden of screening participation, and social influence of Islamic religious leaders had the greatest predictive value for not intending to participate in screening at €70,- non-refundable costs. Perceived severity and possible health benefit were facilitators for this intention measure. These predictions were satisfyingly accurate, as the random forest method retrieved area under the curve scores of 0.72 for intention to request a test and 0.67 for intention to participate in screening at €70,- non-refundable costs. Conclusions By the use of respondent-driven sampling, we succeeded in studying screening behaviour among a hard-to-reach minority population. Despite the limitations associated with correlated data and the sampling method, we recommend to (1) incorporate clarity regarding HBV status, (2) stress the risk of an asymptomatic infection, (3) emphasise mother-to-child transmission as the main transmission route, and (4) team up with Islamic religious leaders to help decrease elements of fatalism, shame, and stigma to enhance screening uptake of Moroccan immigrants in the Netherlands.

Background Timely reporting of infectious disease cases to public health authorities is essential to effective public health response. To evaluate the timeliness of reporting to the Dutch Municipal Health Services (MHS), we used as quantitative measures the intervals between onset of symptoms and MHS notification, and between laboratory diagnosis and notification with regard to six notifiable diseases. Methods We retrieved reporting data from June 2003 to December 2008 from the Dutch national notification system for shigellosis, EHEC/STEC infection, typhoid fever, measles, meningococcal disease, and hepatitis A virus (HAV) infection. For each disease, median intervals between date of onset and MHS notification were calculated and compared with the median incubation period. The median interval between date of laboratory diagnosis and MHS notification was similarly analysed. For the year 2008, we also investigated whether timeliness is improved by MHS agreements with physicians and laboratories that allow direct laboratory reporting. Finally, we investigated whether reports made by post, fax, or e-mail were more timely. Results The percentage of infectious diseases reported within one incubation period varied widely, between 0.4% for shigellosis and 90.3% for HAV infection. Not reported within two incubation periods were 97.1% of shigellosis cases, 76.2% of cases of EHEC/STEC infection, 13.3% of meningococcosis cases, 15.7% of measles cases, and 29.7% of typhoid fever cases. A substantial percentage of infectious disease cases was reported more than three days after laboratory diagnosis, varying between 12% for meningococcosis and 42% for shigellosis. MHS which had agreements with physicians and laboratories showed a significantly shorter notification time compared to MHS without such agreements. Conclusions Over the study period, many cases of the six notifiable diseases were not reported within two incubation periods, and many were reported more than three days after laboratory diagnosis. An increase in direct laboratory reporting of diagnoses to MHS would improve timeliness, as would the use of fax rather than post or e-mail. Automated reporting systems have to be explored in the Netherlands. Development of standardised and improved measures for timeliness is needed.