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National Immunisation Programmes (NIPs) develop historically. Its performance (disease incidences, vaccination coverage) is monitored. Reviewing the schedule as a whole could inform on further optimisation of the programme, i.e., providing maximal protection with the lowest number of doses. We systematically evaluated the performance and strategies of the Dutch pathogen-specific NIP schedules through literature review, assessment of surveillance data and expert opinions. Pathogen-specific vaccinations were categorised according to their strategy of protection: I) elimination or eradication, II) herd immunity or III) 'only' individual protection. The schedule of each vaccine-component was evaluated based on fixed criteria: 1. Is the achieved protection adequate? 2. Is the intended protection achieved? 3. Does the programme include too many or too few doses? 4. Is the timing optimal or acceptable? and 5. Are there drawbacks of the NIP for (part of) the population? Identified issues were explored using surveillance data and literature. Using fixed criteria facilitated comparison between pathogens and revealed opportunities to optimise the Dutch NIP by: i. Reducing the number of polio and tetanus vaccinations; ii. prolonging the interval between diphtheria, pertussis, tetanus, polio, hepatitis B, and Hib vaccine doses for improved effectiveness; iii. Expedite the second measles vaccination from 9 to 2-4 years of age to offer unvaccinated children and primary vaccine failures an earlier chance to be protected; and iv. Delaying the second mumps vaccination to enhance protection in adolescents/young adults. No schedule adaptations were deemed necessary for the vaccines against HPV, rubella, pneumococcal disease, and meningococcal disease. Based on this evaluation the NITAG advised to move the DTaP-IPV-HBV-Hib-booster from age 11 to 12 months, the second MMR-dose from 9 to 2-4 years, replace the Tdap-IPV at 4 years with a Tdap at 5-6 years and move the dt-IPV from 9 to 14 years. Implementation of these changes is planned for 2025., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 The Author(s).)

National Immunization Technical Advisory Groups (NITAGs) are facing increasingly complex vaccination issues together with a lack of human resources for evidence assessment and data analysis. One way to reduce these burdens could be to share some of the preparatory work across NITAGs. We conducted an inventory of all the advisory reports issued by five well-established European NITAGs from 2011 to 2014 to assess overlaps in issues and activities. A total of 104 advisory reports were retrieved. Advisory reports on the same issues were compared to identify overlapping activities and processes. Advisory reports issued by the five NITAGs showed little overlap in issues and processes. A first step towards efficient collaboration would be to establish an independent platform to provide insight into each NITAG's work and to facilitate the exchange of agendas, assessment frameworks and evidence., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Many experts on vaccination are convinced that efforts should be made to encourage increased collaboration between National Immunization Technical Advisory Groups on immunization (NITAGs) worldwide. International meetings were held in Berlin, Germany, in 2010 and 2011, to discuss improvement of the methodologies for the development of evidence-based vaccination recommendations, recognizing the need for collaboration and/or sharing of resources in this effort. A third meeting was held in Paris, France, in December 2014, to consider the design of specific practical activities and an organizational structure to enable effective and sustained collaboration. The following conclusions were reached: (i) The proposed collaboration needs a core functional structure and the establishment or strengthening of an international network of NITAGs. (ii) Priority subjects for collaborative work are background information for recommendations, systematic reviews, mathematical models, health economic evaluations and establishment of common frameworks and methodologies for reviewing and grading the evidence. (iii) The programme of collaborative work should begin with participation of a limited number of NITAGs which already have a high level of expertise. The amount of joint work could be increased progressively through practical activities and pragmatic examples. Due to similar priorities and already existing structures, this should be organized at regional or subregional level. For example, in the European Union a project is funded by the European Centre for Disease Prevention and Control (ECDC) with the aim to set up a network for improving data, methodology and resource sharing and thereby supporting NITAGs. Such regional networking activities should be carried out in collaboration with the World Health Organization (WHO). (iv) A global steering committee should be set up to promote international exchange between regional networks and to increase the involvement of less experienced NITAGs. NITAGs already collaborate at the global level via the NITAG Resource Centre, a web-based platform developed by the Health Policy and Institutional Development Unit (WHO Collaborating Centre) of the Agence de Médecine Préventive (AMP-HPID). It would be appropriate to continue facilitating the coordination of this global network through the AMP-HPID NITAG Resource Centre. (v) While sharing work products and experiences, each NITAG would retain responsibility for its own decision-making and country-specific recommendations., (Copyright © 2016. Published by Elsevier Ltd.. All rights reserved.)

Given the ethical aspects of vaccination policies and current threats to public trust in vaccination, it is important that governments follow clear criteria for including new vaccines in a national programme. The Health Council of the Netherlands developed such a framework of criteria in 2007, and has been using this as basis for advisory reports about several vaccinations. However, general criteria alone offer insufficient ground and direction for thinking about what the state ought to do. In this paper, we present and defend two basic ethical principles that explain why certain vaccinations are the state's moral-political responsibility, and that may further guide decision-making about the content and character of immunisation programmes. First and foremost, the state is responsible for protecting the basic conditions for public health and societal life. Secondly, states are responsible for promoting and securing equal access to basic health care, which may also include certain vaccinations. We argue how these principles can find reasonable support from a broad variety of ethical and political views, and discuss several implications for vaccination policies., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

WHO have long called for universal vaccination against hepatitis B worldwide. However, in north-western Europe low incidence of the disease has fueled debate whether targeted or universal vaccination strategies are the way to go for. Careful assessment has made it clear that the extensive targeted hepatitis B vaccination programmes in the Netherlands nevertheless fail to reach a significant part of the risk groups and have not succeeded in eliminating the disease. Modelling suggests that the public health benefits obtained through targeted programmes could be augmented considerably by universal vaccination. Therefore, the Minister of Health of the Netherlands has decided to implement universal vaccination by October 2011. We illustrate the case of the Netherlands and explore lessons, which can be learnt from the vaccination programmes against HPV and influenza A/H1N1 and how to prepare for a potential public debate that might arise when implementing universal vaccination against hepatitis B., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

To date, the policy to control hepatitis B in the Netherlands is to vaccinate specific risk groups, rather than all children. Low incidence of the disease has fueled debate whether such a targeted vaccination strategy or rather a universal strategy, as recommended by the World Health Organization, is appropriate. The standard framework for assessing whether a particular vaccination should be included in a public programme, as recently proposed by the Health Council of the Netherlands (HCN), was applied to the various options for hepatitis B vaccination. This framework includes seven selection criteria, grouped under five thematic headings: seriousness and extent of the disease burden, effectiveness and safety of the vaccination, acceptability of the vaccination, efficiency of the vaccination, and priority of the vaccination. From about 1990 the disease burden has stayed more or less the same over time and careful assessment has made it clear that the targeted approach has failed to reach a significant part of the risk groups. Models suggest that the public health benefits obtained through targeted programmes could be augmented considerably by universal vaccination. Based on the assessment that universal vaccination means better protection for high-risk groups as well as the whole population, the HCN calls for universal immunisation, even though hepatitis B to a large extent is limited to specific high-risk groups. Should the Netherlands adopt universal vaccination, several immunisation programmes targeted to high-risk groups will, however, remain of crucial importance for years to come., (Copyright © 2010 Elsevier Ltd. All rights reserved.)

As more and more new vaccines are developed and brought to the market, governments have to make decisions about which vaccinations to include in public programmes. This paper describes the experience in the Netherlands in developing a framework for assessing whether a vaccination should be included in the National Immunization Programme (NIP). Bearing in mind the public nature, the factors that determine a vaccine's suitability for inclusion in a communal vaccination programme have been translated into seven selection criteria, grouped under five thematic headings: seriousness and extent of the disease burden, effectiveness and safety of the vaccination, acceptability of the vaccination, efficiency of the vaccination, and priority of the vaccination. The seven criteria and the explanation of them provide a framework for the systematic examination of arguments for and against the inclusion and prioritisation of particular vaccinations. As an illustration, the vaccinations currently provided in the Netherlands through public programmes as well as 23 'candidate' vaccinations are assessed against the seven criteria. The proposed assessment framework including the selection criteria can take full account of the values and specificities as they may differ between situations and countries; the transparency of the approach may help to clarify which elements of the assessment are pivotal in specific situations. Using the criteria furthers a trustworthy, transparent and accountable process of decision-making about inclusion of new vaccinations in public vaccination programmes and may help to retain public confidence., (Copyright 2010 Elsevier Ltd. All rights reserved.)

The recent advice on vaccination against cervical cancer from the Health Council of the Netherlands and the decision by the Minister of Health, Welfare and Sport to implement the vaccination within the National Immunisation Programme by September 2009, has been criticized by a group of authors because five of seven criteria for vaccination in public programmes are considered not to have been met; notably with respect to efficacy and safety. It appears that the available scientific data have been weighted differently by the Health Council committee and the criticising group of authors. In the original advisory report, the committee of the Health Council lists all uncertainties, and argues that a linked monitoring programme will provide public vaccination with sufficient warranties for efficacy and safety. Thus, new opportunities for primary prevention can be taken, and a significant health benefit is likely to be gained. On the other hand, postponing a decision until all uncertainties have been resolved will postpone a significant potential health benefit for many years.

--Each year, 600-700 women in the Netherlands are diagnosed with cervical cancer. Over the last 10 years, an average of 250 women have died annually due to cervical cancer. --Gardasil, the first vaccine for Human papillomavirus (HPV), was recently approved in Europe for the prevention of cervical cancer. --The availability of a vaccine for HPV prompts the question whether it should be included in the Dutch National Immunisation Programme. --At the end of 2006, the Medicines Evaluation Board, the Health Council of the Netherlands and the Centre for Infectious Disease Control of the National Institute for Public Health and the Environment organised a workshop for experts in the field to answer that question. --The HPV vaccine provides protection against HPV-16 and HPV-18, which cause approximately 70% of cervical cancers. --Because the efficacy of vaccination is only evident after many years, preserving good participation in the screening programme is essential. --The current screening could be improved by introducing an HPV test combined with self-sampling for women who do not participate in screening. --Vaccination is unarguably an important development. However, there are still several unanswered questions regarding vaccination and its actual protection, duration of protection, long-term safety and cost-effectiveness. --April 1st, 2008, the Health Council of the Netherlands had recommended including HPV vaccination in the National Immunisation Programme.

The Health Council of the Netherlands (Gezondheidsraad) assessed the vaccination of infants against both group-C meningococci and pneumococci in terms of general criteria and basic principles for inclusion in the national vaccination programme. Vaccination against meningococci C in the Netherlands is expected to prevent about 300 cases of meningococcal disease (meningitis or sepsis), 22 deaths and 12 cases of severe lasting problems (neurological problems or amputations) per year. Vaccination against pneumococci may prevent about 100 cases of meningitis or sepsis, 3200 cases of pneumonia, 36,000 cases of acute otitis media, 11 deaths, 11 cases of severe permanent damage (neurological problems, deafness) per year. The Health Council advised implementing vaccination against group-C meningococci as soon as possible, through 2 injections at the ages of 5 and 6 months or through 1 injection shortly after the child's first birthday, and to carry out a catch-up programme for all children and adolescents up to and including 18 years of age. The council also advised starting a vaccination programme against pneumococci, at ages 2, 3 and 4 months, as soon as the current vaccinations against diphtheria, tetanus, pertussis and polio and against Haemophilus influenzae type b are combined into 1 injection (in 2002 or 2003). In view of the concentration of pneumococci disease in the first years of life, a catch-up programme is not indicated in this case. The Health Council emphasised the importance of microbiological and clinical monitoring of potential adverse effects and of public education programmes. The cost of vaccination against group-C meningococci is comparable to that of other accepted programmes for primary prevention. Compared to other programmes and at the current vaccine price, the cost of vaccination against pneumococci is high.

Objectives: To adapt and improve methodology for back-calculation of AIDS in Europe and to examine the feasibility of estimating past HIV incidence by birth cohort., Methods: Empirical Bayesian back-calculation (EBBC) used Markov disease progression models, modified to allow for three diseases added to the AIDS case definition in 1993 and for pre-AIDS mortality, and estimation by penalized maximum likelihood with a neighbour prior. EBBC by 5-year birth cohort assumed a minimum age at infection and age-dependent progression rates; three versions, with varying age effects, were investigated using AIDS cases diagnosed prior to the introduction of highly active antiretroviral therapies (HAART)., Results: Compared with the no age-effect version, EBBC by birth cohort tended to produce flattened HIV incidence curves in country-exposure groups with < 1000 AIDS cases, reflecting effects of the neighbour prior when data become sparse. Otherwise, birth cohort analysis, with moderate effects of age on progression, gave initially increasing incidence curves and consistent patterns across countries, with the 1960-1964 cohort most affected. In the European Union, incidence is estimated to have peaked in 1983 among homosexual men and in 1988 among injecting drug users; 460000 persons were estimated to be living with HIV/AIDS at the end of 1995., Conclusions: Our improved methodology deals effectively with the change in AIDS case definition and has allowed quantitative assessments of the HIV epidemic by birth cohort using all AIDS cases diagnosed before 1996, thus providing a sound basis for public health policy at a time when estimation of more recent prevalence is compromised by the effects of HAART.

Background: The long average incubation time from HIV infection to AIDS makes it difficult to estimate recent HIV transmission from AIDS incidence data. Age-period-cohort (APC) analysis can separate out the effects of age, calendar time and birth cohort to provide a clearer picture of transmission trends., Methods: AIDS incidence data from 1981 to 1994 among intravenous drug users (IDU) for 12 Western European countries were used. Yearly incidences per 100,000 population or 100,000 person-years were calculated by age at diagnosis and 5-year birth cohort (1950-1954, 1955-1959, 1960-1964, 1965-1969 and 1970-1974), and corrected for reporting delay. Incidence patterns were compared between birth cohorts and countries., Results: For most countries the impact was greatest on the cohort born 1960-1964. Comparing incidence patterns in the 1965-1969 to 1960-1964 cohorts suggest the epidemic has plateaued at low to intermediate levels in Austria, Greece and the North-Western European countries, and at high levels in France, Italy and Switzerland. For most countries transmission amongst the 1970-1974 as compared to the 1965-1969 cohorts could not be assessed due to small numbers and short follow-up time. In Spain the epidemic was uncontrolled with a high incidence among recent birth cohorts. In Portugal the epidemic was still at an early and expanding phase., Conclusions: The APC analysis revealed large country differences in the dynamics of the HIV/AIDS epidemic among IDU. Full interpretation of these differences is dependent on information from other sources about the local public health response and trends in drug injecting behaviours. Earlier introduction of the virus and higher prevalence of injecting drug use may explain some of the generally higher incidence in Southern European countries, but the larger part of it is most likely explained by local characteristics of drug users, such as younger age and more frequent sharing of needles and syringes, and a less effective public health response.

Background: The effects of the implementation of a new Dutch hepatitis B virus (HBV) vaccination strategy (1991) for expatriates on HBV vaccination status and HBV infection prevalence were evaluated in a group of 864 expatriates returning from HBV-endemic areas., Methods: During a routine medical examination at the participating medical centres Dutch expatriates were asked to complete a questionnaire and to donate a serum sample for HBV testing. Blood was tested for antibodies against the hepatitis B core (anti-HBc) and surface antigens (anti-HBs). The serological data were related to information gathered on aspects of residence, sexual risk behaviour and occupational risks., Results: A significantly higher percentage of expatriates (37%) were vaccinated compared to a previous study in 1987-1989 (14%). However, the percentage of expatriates with HBV infection markers (5%) had not decreased significantly. Moreover, the risk for HBV infection, as determined with a questionnaire, was still affected by well-known risk factors such as homosexual contacts (odds ratio [OR] = 6.6, 95% CI: 1.7-26), more than five casual local partners (OR = 3.6, 95% CI: 1.2-11) and more than five occupational accidents in the last 3 years (OR = 20, 95% CI: 2-187). Detailed analysis of the vaccination status indicated that especially young female expatriates with low risk behaviour (65%) were protected, while older male expatriates with high risk behaviour were less protected (20%)., Conclusion: We conclude that the new vaccination strategy has resulted in a higher percentage of expatriates protected. However, only a small proportion was reached of those at highest risk for HBV infection.

Objective: To estimate the cost effectiveness of universal, voluntary HIV screening of pregnant women in England., Design: Cost effectiveness analysis. Cost estimates of caring for HIV positive children were based on the stage of HIV infection and calculated using data obtained from a London hospital between 1986 and 1996. These were combined with estimates of the health benefits and costs of antenatal screening so that the cost effectiveness of universal, voluntary antenatal screening for HIV infection in England could be estimated., Main Outcome Measures: Lifetime, direct costs of medical care of childhood HIV infection; life years gained as a result of the screening programme; net cost per life year gained for different pretest counselling costs; and different prevalence rates of pregnant women who were unaware that they were HIV positive., Results: Estimated direct lifetime medical and social care costs of childhood HIV infection were pound178 300 using a 5% discount rate for time preference (1995-6 prices). In high prevalence areas screening pregnant women for HIV is estimated to be a cost effective intervention with a net cost of less than pound4000 for each life year gained. For areas with comparatively low prevalence rates, cost effectiveness could be less than pound20 000 per life year gained, depending on the number of pregnant women who are unaware that they are infected and local screening costs., Conclusions: Our results confirm recent recommendations that universal, voluntary antenatal HIV screening should be implemented in the London area. Serious consideration of the policy should be given for other areas in England depending on local prevalence and screening costs.

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.

Among people who work abroad, sexual activity and therefore the risk of HIV infection appear to be relatively high. Little is known about the factors that influence sexual conduct when staying abroad, separated from their usual social environment. This is why 55 expatriates who had been sexually active in AIDS endemic areas were selected for an in-depth interview from the original sample of 864 Dutch expatriates participating in a study on sexual behaviour and HIV infection. The social and cultural context in which the sexual contacts took place was addressed in these interviews. Qualitative analysis of the data led to the identification of four styles with regard to the meaning of and motivations for having sex abroad: 'the unprepared', 'the fanatical', 'the unaffected' and 'the slightly accessible'. These styles are described separately and attention is paid to the association of these styles with protection behavior.

Objectives: To compare HIV prevalence estimates (total number infected) by using extrapolation from surveys on infection rate and risk behaviour (EIR) in specific segments of the population and back-calculation (BC) on reported AIDS cases. To discuss potential sources of bias and error, and to identify areas for improvement of the methodology., Design: Systematic comparison and epidemiological assessment of data input, underlying assumptions, and output., Methods: Low, possibly unbiased and high estimates of HIV prevalence as of January 1996 for homo/bisexual men, injecting drug users. heterosexual men and women with multiple partners, and blood transfusion recipients and haemophiliacs were derived from surveys and continuous data collections on HIV infection rate and risk behaviour in the Netherlands between 1992 and 1996. These were compared with estimates (point and 95 % CI) by empirical Bayesian BC on AIDS cases 1982-1995., Results and Conclusions: The estimate of HIV prevalence by EIR was 13,806 with low and high estimates of 9619 and 17,700, respectively. The HIV prevalence estimate by BC was 8812 (95% CI: 7759-9867). The available data from EIR are too limited for accurate estimates of HIV prevalence. EIR estimates could be improved considerably with more precise data on prevalence of risk behaviours and HIV prevalence rate for homosexual men. More confidence can be put in the BC estimates, but these could be underestimates because of the age effect on incubation time, pre-AIDS treatment and relapse of risk behaviour. BC estimates could be improved by a better representation of the incubation time distribution (including the effect of age there-upon), better data on the effectiveness and uptake of pre-AIDS antiretroviral treatment and prophylaxis of opportunistic infections, and on the level of underreporting.

In this study on occupational risks of HIV infection among 99 Dutch medics working in AIDS endemic areas, 61% reported percutaneous exposures during an average stay of 21 months. The mean number of injuries was lower among physicians (2.0 versus 3.9 per year) and higher among nurses (1.9 versus 1.2) than in previous research conducted in 1987-1990 among Dutch medics returning from Africa. But the reduction of exposures among physicians might be explained by the fact that the number of procedures they carried out was less in the later study. Also among nurses a shift of tasks was seen. On the basis of an estimated HIV prevalence in the patient population of 19%, a chance of transmission per accident of 0.3%, and 1.9 percutaneous exposures per year, the mean occupational risk of HIV infection per year can be estimated at 0.11% per person. Besides length of stay and number of activities, characteristics of the work setting were associated with the frequency of different kinds of injuries. From the analysis of 109 extensive descriptions of recent accidents, it appeared that the majority of the injuries occurred during routine activities and were self-inflicted. Injuries with hollow needles usually occurred after the actual medical act (e.g. during recapping). Carelessness (e.g. due to fatigue) or being in a hurry (e.g. because of an emergency) were also often the cause of percutaneous injuries, as were the poor quality of the equipment, lack of professional skills, or a combination of these factors. Prevention activities are still important to reduce the frequency of occupational exposures. But they will not eliminate them totally; from the descriptions of recent exposures it was clear that some of the injuries occurred in spite of precautions.

Among mental disorders associated with HIV infection, dementia is the one most likely to have a major impact on public health, both as a result of the high levels of individual disability, and the greater demand of health care resource utilization. Epidemiologic and economic impact of HIV-associated dementia needs to be estimated, in order to provide policy makers and health managers with the information required for decision making and resource allocation. An increase in HIV encephalopathy prevalence rates may be expected as a consequence of longer survival time in dementia patients and in patients with other AIDS defining disease (longer survival increases the risk of developing HIV encephalopathy). A resource utilization study shows that, in the chronic stage of the disease, in-patient days per person-year are almost double in AIDS subjects with neurological complications as compared with those without neurological complications; no major difference appears when considering out-patients consultations and day-care treatments. In conclusion, a significant rise in resource utilization and in related costs may be anticipated as a consequence of the increasing prevalence of HIV encephalopathy. Further studies seem necessary to compare different approaches in the management of this debilitating disease, in view of a more rational utilization and allocation of resources.

Objectives: To study trends in AIDS incidence in Europe by age and year of birth., Design: Age-period-cohort analyses were adopted to distinguish the different time factors of calendar year, age and year of birth., Methods: Non-aggregate AIDS incidence data from 12 European countries (1978-1994) were adjusted for reporting delay and expressed per unit of population (per 100000 persons or 100000 person-years). Age-specific incidence patterns (absolute level and rate of increase) were compared between 5-year birth cohorts for homo-/bisexual men, injecting drug users (IDU) and heterosexual contact cases., Results: Mean age at diagnosis increased strongly amongst IDU, but less so among homo-/bisexual men and heterosexual contact cases. Of a total 110646 reported cases (116311 after adjustment for reporting delay), 87167 (78.8%) were among people born in 1950-1974 [91951 (79.1%) after adjustment for reporting delay]. The relative impact on specific birth cohorts differed strongly by exposure group. Incidences at age ranges of 20-24 and 25-29 years among cohorts born in 1965 and after were about the same level (homo-/bisexual men, IDU) or higher (heterosexual contact cases) than older birth cohorts when these were in the same age range; rates of increase were less among homo-/bisexual men and IDU, but higher among heterosexuals. There were large differences between counties., Conclusions: Overall, AIDS incidence among cohorts born in 1965 and after is about the same level (homo-/bisexual men, IDU) or higher (heterosexual contact cases) than older cohorts when these were in the same age range. Rates of increase of AIDS incidence curves suggest reduced HIV transmission amongst the most recent cohorts of homo-/bisexual men and IDU, but among young heterosexuals the epidemic is still expanding.

An abrupt decrease of the number of reported new AIDS cases took place in the first half of 1997 in the Netherlands. This decrease was most prominent in homosexual/bisexual men and intravenous drug users, and less conspicuous in heterosexual men and women. The number of heterosexual patients with a non-Dutch nationality even increased compared with the first half of 1996. The most probable explanation of these observations is the introduction of improved treatment possibilities for HIV-infected people starting July 1996, which lead to a longer incubation period. Owing to these developments monitoring the HIV/AIDS epidemic in the Netherlands will depend more and more on HIV status surveillance instead of on registration of new AIDS cases.

Objective: To assess the prevalence of HIV infection and related risk factors among Dutch expatriates returning from assignment in sub-Saharan Africa, Latin America, and South and South-east Asia., Methods: From July 1994 to January 1996, a questionnaire on the risks of sexual exposure was completed by 864 respondents, and blood samples were taken., Results: Of the 634 men, 41% reported having sex with casual or steady local partners and 11% with casual or steady expatriate partners, during an average stay of 26 months in the previous 3 years. Of the 230 women, these figures were 31 and 24%, respectively. Of the men with local casual partners (29%), 59% paid for sex at least once. For men as well as women, having sexual contacts abroad was associated with younger age, positive intention prior to departure to have sex abroad, being single at departure, and, only for the men, working for a commercial organization, and feelings of loneliness and boredom. Among men, consistent condom use with casual local partners was 69%, and with casual expatriate partners 63%. Among women, these figures were 64 and 48%, respectively. Consistent condom use with steady local or expatriate partners was much lower. Among men, non-consistent condom use with casual partners was more prevalent if they had been abroad for a longer time, condoms were not taken along from The Netherlands, the country where they were posted was Asian, and the estimated HIV prevalence among the local population was lower. Among the women, non-consistent condom use was more prevalent if condoms were not taken along, and if they did not have the intention before departure to have sex abroad. Of the persons from whom blood could be obtained, one man was HIV-positive. Another man who refused to participate in the study indicated that he was HIV-positive., Conclusions: Although 23% of the expatriates had unprotected sex with partners from endemic areas, very few HIV infections were found. In comparison with a previous study among this population carried out in 1987-1989, which found five out of 1968 expatriates to be HIV-infected, consistent condom use with casual local partners did increase considerably (from 21 to 67%). However, health education is needed to reduce the risk of HIV infection, which should emphasize the sociocultural differences in sexual practices.

Objective: To document the recent developments in the course of the AIDS epidemic in the Netherlands, 1982-1995., Design: Descriptive., Setting: National Institute of Public Health and Environment, Bilthoven, Municipal Health Service, Amsterdam, and Inspectorate of Public Health, Rijswijk, the Netherlands., Method: Based on the new AIDS patients reported to the Inspectorate of Public Health, the incidence figures were calculated by risk group (homo/bisexual men, intravenous drug users and heterosexual men and women), by birth cohort defined by 5 successive years of birth, and by nationality, in order to characterise sub-epidemics., Results: Among homo/bisexual men AIDS incidence has been stabilizing in recent years. Among intravenous drug users and heterosexuals incidence continues to rise but at a low level compared with homo/bisexual men. Among homo/bisexual men and intravenous drug users mean age at AIDS diagnosis is rising in conjunction with reduced incidence among young persons born in 1965-1969 when compared with the incidence among persons born in 1960-1964 when at the same age. By contrast, among heterosexuals a decline in mean age at diagnosis is observed and this decline coincides with undiminished rise of incidence among persons born in 1965-1969. Among heterosexual patients an increasing and disproportionate number have the nationality of a sub-Saharan African country., Conclusion: Future AIDS incidence among homo/bisexual men and intravenous drug users will probably be lower than it currently is. Regarding heterosexuals the undiminished growth of the number of young AIDS patients and the increasing proportion of patients from abroad make such an assessment more difficult.

Within a surveillance programme in a Regional Public Health Laboratory anonymous information on HIV test, requesting physician and tested individual is automatically selected, regardless of test result. Thereby, personal identifiers are transformed into unique but meaningless numeric codes. Besides, requesting physicians receive a questionnaire on indication for testing (response 87%). Between April 1989 and June 1993 12,219 HIV tests were performed in 10,972 individuals. The percentage of positive tests (2.1%) was twice the percentage of positive individuals (1%). No increase in number of new infections was observed over time. Of individuals, 41.6% were tested due to third party requests (mainly insurance): HIV was demonstrated once (0.03%). Among the remainder, with medical indications, seroprevalence was 1.4%. At relatively little expense, we were able to provide valid information about patterns of HIV-testing and HIV seroprevalences among people tested in routine medical practice. Prevention of double counts proved to be important. Extension to other Dutch areas is expected.

Objectives: To assess the prevalence of HIV infection among intravenous (IDU) and non-intravenous drug users in Heerlen and Maastricht (Southern Netherlands), to detect subgroups of IDU with a higher risk of HIV infection, and to assess the risk of further spread of HIV., Design: Cross-sectional study., Setting: Heerlen, Kerkrade, Brunssum and Maastricht, the Netherlands., Methods: Between August 15 and November 25, 1994, a saliva specimen and a short questionnaire were obtained from 449 drug users (340 IDU) in Heerlen (and environs) and Maastricht. Participants were recruited through methadone care (54%), syringe exchange (16%), a street prostitution project (3%), street recruitment (23%) and other drug users (4%)., Results: Of the 340 IDU 33 were infected (prevalence: 10% (95% confidence interval: 7-13)), among the 109 non-IDU no infections were found (0% (0-3)). IDU making use of the syringe exchange had a higher prevalence (odds ratio 3.13 (1.37-7.61)). In logistic regression analysis, this finding could not be explained by selection on more risky injecting. One in five currently injecting IDU reported having used someone else's used needle or syringe in the last 6 months. One in five IDU had a non-drug user as steady sexual partner. In sexual contacts between steady partners condom use was low. On the basis of self-reported serostatus it appeared that some infections have taken place in the last two years., Conclusions: The prevalence of HIV infections among IDU in Heerlen and Maastricht is about 10%. IDU using the syringe exchange have a higher prevalence. This means this prevention reaches the high-risk group, but probably can not avoid all infections. The risk of further spread among IDU is high. The risk of spread to non-IDU and non-drug users is present.

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.

Objective: Description of the epidemiology and transmission categories of AIDS in the Netherlands., Design: Descriptive., Setting: The Netherlands., Method: Analysis of all registered AIDS patients until 31 December 1993. Trends in the composition of this population were studied with respect to age and sex, risk groups, geographic distribution across the country, heterosexual transmission, AIDS-defining diseases and reporting pattern., Results: From the first patient in 1982 until December 31, 1993, a cumulative total of 2912 patients was diagnosed and reported in the Netherlands (2995 when corrected for reporting delay). The numbers of reported AIDS cases in the Netherlands are smaller than previously predicted by mathematical models. The proportion of homosexual men in the incidence of AIDS dropped from 89 to 73 per cent, the proportions of intravenous drug users and heterosexual transmission rose to 11 per cent each. Patients in the category of heterosexual transmission are mainly individuals from countries where heterosexual contact is the dominant mode of transmission and their sex partners, and to a lesser extent the sex partners of intravenous drug users (whether or not in relation to prostitution). The proportion of women is rising (229 patients or 8 per cent by December 1993), with most cases transmitted initially by intravenous drug use but later by heterosexual contact., Conclusion: The number of AIDS cases in all risk groups combined is levelling off. However, more detailed analysis shows that the numbers of cases of heterosexual transmission and those in young homosexual men are still rising. For a better quantitation of the quality of the AIDS data, specific research into underreporting and non-diagnosis of AIDS cases in the Netherlands is warranted.

The risk for dentists to acquire HIV infection at work is low but not neglectable. Needlestick injuries are among the most hazardous events in this respect. Prevention of these injuries will considerably reduce the risk of occupational HIV infection in dentistry.

An outbreak of mainly extrapulmonary tuberculosis (TB) in a group of about 550 patients with rheumatoid arthritis (RA) is described. These patients had been attending the practice of a former general practitioner who treated cases of rheumatoid arthritis with phenylbutazone and steroids. The number of diagnosed TB cases was 55. Six cases had a contagious lung localisation. The possible sources of the outbreak were analysed. Both a visit on a same day as a sputum positive patient (chi 2-trend: 20.4; p < 0.001) and the administration of steroids (odds ratio (OR): 36.2; 95% confidence interval (CI): 8.8-313) were independent risk factors. There also appeared to be a relationship between TB and RA (OR: 4.4; 95%-BI: 2.2-9.1). Exogenous re(infection) and endogenous reactivation are possible causes of this outbreak.

Serum samples from 127 Dutch forestry workers and 127 matched controls were tested for antibodies against Borrelia burgdorferi in an indirect immunofluorescence assay (IFA). Those of the forestry workers were also tested by Western blotting. The forestry workers were examined clinically for evidence of Lyme borreliosis without the examiner or the workers knowing the results of the laboratory tests. Seroprevalence of B. burgdorferi antibodies among forestry workers (25/127) was significantly higher than among controls matched for age and place of residence (8/127), odds ratio 3.7 (95% CI 1.5-9.7). Of the 25 sera of forestry workers positive in the IFA, 23 reacted with at least five bacterial polypeptides in the Western blot test. According to adapted CDC criteria, seven forestry workers (6%) were classified as being a case of Lyme borreliosis. In only one of them had the diagnosis been made before this investigation. Five persons had a history of erythema migrans, one of arthritis, and one of persistent infection. We conclude that Lyme borreliosis is an occupational disease among forestry workers in the Netherlands, with a three-fold higher seroprevalence than among matched controls. The disease, often not diagnosed among this high-risk group, warrants more attention to achieve early recognition and to prevent late complications.

In order to study the prevalence of human immunodeficiency virus (HIV) infections and related risk factors, Dutch expatriates returning from sub-Saharan Africa were asked to complete a questionnaire on sexual, occupational and other risk factors, and to donate a sample of blood to test for antibodies against HIV. The 1968 participants were workers of various professions and their family members over 16 years of age posted in sub-Saharan African countries by Dutch governmental, non-governmental and commercial organizations for at least 6 months cumulative time between 1 January 1979 and 1 January 1990. Antibodies against HIV-1 were found among 4 of 1122 men (0.4%) and 1 of 846 women (0.1%). The woman and 3 of the men had had sexual contact with African partners and had been treated for sexually transmitted diseases, 2 of these 3 men also had an African life partner. One man reported occupational exposure only. Of the 1968 participants 89 men (7.9%) and 18 women (2.1%) lived with an African partner; 344 men (30.7%) and 111 women (13.1%) had heterosexual contact with other African partners. Only 22.3% (men) and 18.6% (women) of casual sexual contacts with African partners were always protected by a condom. Two hundred and thirty-two of 408 (56.9%) (para)medics reported needlesticks. Groups at risk of HIV infection through sexual exposure were identified using logistic regression models. In conclusion, the observed prevalence of HIV-1 is low. However, unprotected sexual contact with African partners and needlestick accidents were common. This study underscores the continuous need for health education of expatriates on the risks of transmission of HIV in Africa.

A literature review revealed 33 reports of health care workers who have contracted HIV infection as a result of their work. Four of these were expatriate doctors who had worked in Africa. The commonest mode of transmission was needlestick injury, but several infections acquired through contact or skin or mucous membrane with infected blood have been reported. In this paper we outline how the risk of HIV infection in a health care worker can be estimated for a given number of exposures. The formula is based on the known likelihood of transmission per needlestick, the seroprevalence rate among patients, and the number of needlestick injuries that occur. We also suggest a list of measures by which the risk of HIV transmission to hospital staff can be minimized.

In the Netherlands by the 1st of January 1990 1074 AIDS patients have been reported to the Department of the Chief Medical Officer. In the last few years the proportion of intravenous drug users increased and the proportion of homo/bisexual men decreased. After adjustment for the effect of delay in reporting the total number of AIDS patients by 1st January 1990 is estimated to be 1173. It appears that the reporting delay outside Amsterdam is longer than in this city. The time required for doubling of the half-yearly incidence of new AIDS patients (doubling time, dt) increased from 9 months in the beginning of the epidemic to 34 months. It is expected on the assumption of constant dt that 1120 new AIDS patients will be diagnosed in 1990 and 1991 together. The present growth among the homo/bisexual men (dt 34 months) is smaller than the one among the intravenous drug users (dt 23 months). The growth in Amsterdam (dt 36 months) is less than that in the rest of the Netherlands (dt 32 months). Based on the course of the AIDS epidemic the number of HIV infected (including the AIDS patients) is estimated as 9,000-12,000 by the 1st of January 1990.