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Biomedical subjects

J A van den Hoek

Publications and source records attributed to J A van den Hoek.

At least 19 recordsLinked to original sources
PubMed2003

[Shigellosis, a sexually transmitted disease in homosexual men].

A study of the registered number of Shigella infections in Amsterdam for the period 1997-2001 revealed that in 2001, there was an increase in the number of homosexual patients with oral-anal contacts as source for their infections. All of these infections were caused by subtype Shigella sonnei. The infections were not associated with a specific meeting place for homosexual men. A relationship with an underlying HIV-infection is likely.

Adolescent↗
PubMed2003

[HIV-screening among pregnant women in the region of Amsterdam in 2002].

In 2001, the Municipal Health Service started offering HIV tests to all pregnant women in and around Amsterdam. All midwives and all hospitals but one participated in this HIV screening. In 2002, of the 10,752 pregnant women offered HIV testing 13.6% refused. HIV antibodies were detected in 24 women (0.26%). The HIV prevalence was doubled compared to the prevalence in 1990-1991, but the number of newly HIV-infected pregnant women remained stable (0.1%). The high number of refusals, as a result of which many HIV-infected women might be missed, is alarming. For this reason, in January 2003, the Municipal Health Service started HIV testing by the opting-out approach. Under the opting-out approach, women are notified that an HIV test will be included in the standard test battery, together with tests for hepatitis B and syphilis, unless she explicitly refuses. It is expected that the opting-out approach for HIV screening of pregnant women will be implemented nationwide in 2003.

Adult↗
PubMed2003

HIV testing behaviour among heterosexual migrants in Amsterdam.

This cross-sectional study among heterosexual migrant groups in south-eastern Amsterdam, the city area where the largest migrant groups live, provides an insight into HIV testing behaviour in this particular group. Participants were recruited at street locations (May 1997-July 1998) and interviewed using structured questionnaires. They also donated saliva for HIV testing. In total, 705 males and 769 females were included in this study (Afro-Surinamese (45%), Dutch-Antilleans (15%) and West Africans (40%)). Prior HIV testing was reported by 38% of all migrants (556/1479), of which only a minority (28%) had actively requested HIV testing. Multivariate logistic regression showed that not actively requesting HIV testing was more likely among younger (< 23 years) migrants, especially women (ORwomen: 4.79, p < 0.01, ORmen: 1.81, p < 0.05). Furthermore, women without previous STI treatment (OR 2.19, p < 0.05) with Afro-Surinamese ethnicity (OR 2.12, p < 0.05), men without health insurance (OR 2.17, p < 0.05) and with low education (p < 0.01) were also more likely to not actively request HIV testing. Active requests for HIV testing in case of HIV risk should be facilitated by promoting HIV testing and by improving accurate self-assessment of risk for HIV infection, especially among the groups that do not actively request HIV testing. This would increase HIV awareness and provide the opportunity of better medical care earlier in HIV infection.

Adolescent↗
PubMed2001

Evaluation of the hepatitis B antenatal screening and neonatal immunization program in Amsterdam, 1993-1998.

In the enhanced antenatal hepatitis B screening and neonatal immunization program in Amsterdam, 691 hepatitis B surface antigen (HBsAg) positive expectant mothers were reported in the period 1993-1998. The coverage of the screening was calculated at 97%. HBsAg-prevalence was high in women from Ghana and South-East Asia, and lowest in Dutch women. Hepatitis B immune globulin (HBIg) was administered within 24h to 95.9% of the neonates; 99.7% completed the vaccination series. About 6 weeks after the third vaccination the titer antiHBs was > or =100 IU/l in 85% of children; in 12% the titers were 10-100 IU/l; 3% had titers <10 IU/l, of whom 3/521 initially had HBsAg. Low birth weight (OR 3.77), being a boy (OR 1.64) and country of origin were predictors of low postvaccination titers. Coordinated by 0.5 full time equivalent (fte) additional staff, the program was relatively cheap and successful.

Adult↗
PubMed2000

[Screening for asymptomatic Chlamydia trachomatis infection in pregnancy; cost-effectiveness favorable at a minimum prevalence rate of 3% or more].

OBJECTIVE: To estimate the cost-effectiveness of antenatal screening for Chlamydia trachomatis. DESIGN: Pharmaco-economic model analysis. METHOD: The risks of C. trachomatis infection during pregnancy and of complications of the infection as well as the cost of screening for complications (pelvic inflammatory disease, chronic pelvic pain, ectopic pregnancy, infertility and neonatal pneumonia) and of treatment were estimated. Assumed were a ligase chain reaction on urine and treatment of identified infected cases with erythromycin or amoxicillin (second choice). Cost-effectiveness was calculated and presented in net direct and indirect costs per major complication averted. RESULTS: For C. trachomatis prevalences in pregnancy above 4% benefits exceed the costs. For prevalences between 2.82% and 4.00% net costs are positive, but a major complication averted costs less than f 1000.-. Considering sensitivity analysis as well, screening for C. trachomatis at prevalences above 3% costs less than f 1000.-per major complication averted and might even save costs. No recent Dutch data on C. trachomatis prevalence in pregnancy are published however. CONCLUSION: Given the current information, antenatal C. trachomatis screening can be recommended from a pharmaco-economic perspective if C. trachomatis prevalence in pregnancy is 3% or more.

Adolescent↗
PubMed2000

Strong decline in herpes simplex virus antibodies over time among young homosexual men is associated with changing sexual behavior.

The objective of this study was to evaluate whether the change in sexual behavior among homosexual men observed after the start of the acquired immunodeficiency syndrome epidemic resulted in a change in herpes simplex virus (HSV) seroprevalence in this group over time. In a cross-sectional study, the prevalence of herpesvirus types 1 (HSV1) and 2 (HSV2) was determined at study entry in 1984-1985 and 1995-1997 among 532 young (aged < or = 30 years) homosexual men participating in the Amsterdam Cohort Studies on HIV/AIDS. Risk factors for the presence of HSV antibodies, including human immunodeficiency virus infection, were evaluated, and their influence on HSV prevalence over time was assessed. A strong decrease in HSV1 and HSV2 seroprevalence, from 80.6% to 59.0% and from 51.3% to 19.0%, respectively, was observed between the two time periods. This decrease was not markedly influenced by various demographic and socioeconomic factors. After data were controlled for several markers of sexual activity (such as number of sex partners, human immunodeficiency virus infection, and past episode(s) of gonorrhea), it appeared that the decline in HSV seroprevalence was explained by a concurrent decrease in the presence of these markers. The authors conclude that among young homosexual men in this study, the strong decrease in HSV seroprevalence was associated with a concurrent shift in sexual behavior. Furthermore, these data suggest an increasing sexual component in HSV1 transmission over time.

Adult↗
PubMed2000

[Shigellosis in Amsterdam, 1991-1998: incidence and results of contact tracing].

OBJECTIVE: To determine the incidence of reported shigellosis in Amsterdam (1991-1998) and the factors related to the secondary attack rate of shigellosis. DESIGN: Retrospective. METHODS: From an automated data bank data were collected on all registered shigellosis patients in Amsterdam in the period 1991-1998, and their contacts found by contact tracing. RESULTS: 567 Patients with shigellosis had been reported and a Shigella infection has been diagnosed in 96 of the 983 contacts. The annual incidence decreased statistically significantly from 13 to 8/100.000. 329 males and 334 females were infected. The highest number of cases was found in children from 0-4 years and among adults from 20-34 years. Of the 663 patients 106 (16%) required hospitalization; for children under 7 this proportion was 30% (32/108). Among the contacts (excluding the 14 contacts with the same foreign source and the same first sickness day as the index patient) the secondary attack rate was 8%. Young age, of both the patient and the contact was independently related to a higher secondary attack rate. CONCLUSION: With contact tracing for shigellosis a large number of secondary infections were found. Given the high infection rate and large number of hospitalisations among children, contact tracing should focus at this young age group.

Adolescent↗
PubMed2000

[Pharmaco-economic evaluation of mandatory HIV-screening in pregnancy; a cost-efficacy analysis in Amsterdam].

OBJECTIVE: To estimate the cost effectiveness of universal screening for HIV of pregnant women in Amsterdam. DESIGN: Pharmaco-economic model calculation. METHOD: An estimate was made of the minimal and maximal prevalences of undiagnosed HIV infection during pregnancy for the whole of Amsterdam, based on epidemiological data from observation among pregnant women in two Amsterdam hospitals and one obstetrical practice. The calculation was based on universal screening with an ELISA test. The interventions after screening comprised pharmacotherapy during pregnancy, delivery by caesarean section and breast-milk substitution. The issues of pharmaco-economic analysis were whether or not costs were reduced and net costs per year of life gained; the question was also studied at what lifetime costs of care for HIV infected children the net costs would be nil (costs equal benefits). RESULTS: Universal HIV screening in Amsterdam required a total investment of about Dfl 300,000.-per annum. In many of the analysed options for HIV screening the financial profits exceeded the investment. Variation of assumptions showed that the net costs of HIV screening under all conditions investigated would remain below Dfl 1,200.-per life year gained. CONCLUSION: Universal HIV screening of pregnant women in Amsterdam showed a favourable cost effectiveness. The calculations indicated a possibility of reducing costs.

Adult↗
PubMed1999

[Opportunistic screening for genital infections with Chlamydia trachomatis among the sexually active population in Amsterdam. III. Cost-effectiveness analysis of screening women and the role of reinfection and partner treatment].

The role of reinfection and the importance of partner treatment were added to a pharmacoeconomic model for the analysis of a GP-based opportunistic screening programme for Chlamydia trachomatis (CT) in sexually active women in Amsterdam. A favourable cost-effectiveness was found for partner treatment. Partner treatment was cost saving and overall net costs per major outcome averted by the screening programme were reduced by 40% or more due to partner treatment. From a pharmacoeconomic point of view partner treatment should be routinely provided in the framework of a CT screening programme for Amsterdam women.

Adolescent↗
PubMed1999

[Opportunistic screening for genital infections with Chlamydia trachomatis among the sexually active population of Amsterdam. Il Over 90% participation and almost 5% prevalence].

OBJECTIVE: To determine in an opportunistic screening programme for Chlamydia trachomatis (CT) the participation and the CT prevalence among the heterosexual population. METHODS: Heterosexually active men and women, 15-40 years old, who consulted a general practitioner in Amsterdam, the Netherlands, in the period May 1996-April 1997, without symptoms of a sexually transmitted disease, were asked after informed consent had been given to provide a first-voided urine sample and a few sociodemographic data. The urine was investigated for CT by means of a ligase chain reaction. In case of a CT infection, the general practitioner was asked for information on treatment and partner notification. RESULTS: A total of 3689 persons were eligible for the study of whom 214 (5.8%) refused participation. Men refused more often than women (9.0% and 4.3% respectively). No relation was found with ethnic background or health care insurance (national health cost insurance/private medical insurance). Refusers were somewhat younger than participants (not statistically significant). CT was diagnosed in 4.9% (95% confidence interval (95% CI): 4.1-5.9) of the women and in 4.7% (95% CI: 3.6-6.1) of the men. In women a decreasing trend was seen in the prevalence of CT with an increase in age: from 13.4% in the group 15-19 years old to 2.3% in the group 35-40 years old. Independent of age a higher prevalence was found in Surinam Creole women. In 83% of the CT patients the general practitioner spoke with the patient about partner notification; usually there was one partner. CONCLUSION: There was a high participation rate (94%) in this opportunistic screening programme in which urine was tested for presence of CT. The CT prevalence in this asymptomatic population was almost 5%, but it was significantly higher in young women and women from Surinam. It is proposed to start such a screening programme in all general practices in Amsterdam.

Adolescent↗
PubMed1999

[Opportunistic screening for genital infections with Chlamydia trachomatis in sexually active population of Amsterdam. II. Cost-effectiveness analysis of screening women].

OBJECTIVE: To estimate the cost effectiveness of Chlamydia trachomatis (CT) screening of young women visiting general practitioners. DESIGN: Economic model analysis. METHODS: Data on the health care needs for CT complications were derived from various sources; costing was done using estimated cost prices, charges and the friction cost method; epidemiological data were derived from a pilot study among 22 general practices in Amsterdam, the Netherlands. The analyses were carried out assuming screening with ligase chain reaction test of a urine sample and treatment of identified cases of infection with single-dose azitromycin. The model intervention consisted of screening all heterosexually active women aged 15-19, 15-24, 15-29, or 15-34 years (strategies 1, 2, 3 and 4, respectively). Cost effectiveness was presented in net direct and indirect costs per woman cured and per major outcome averted (pelvic inflammatory disease (PID), chronic pelvic pain, ectopic pregnancy, infertility and pneumonia of newborns). RESULTS: The first two strategies were cost saving. For the third strategy net costs per woman cured and per major outcome averted were almost 110.- Dutch guilders (DFL) and over DFL 300, respectively. The last strategy costs over DFL 320 per woman cured and over DFL 910 per major outcome averted. The cost effectiveness was sensitive to the assumed probability of progression of CT infection to PID. CONCLUSION: Universal implementation of the screening programme investigated in Amsterdam for women aged 15-24 years would result in approximately equal savings and costs. Screening of all 15-29-year-old women would require a net investment of DFL 350,000.

Adolescent↗
PubMed1998

[Surveillance of AIDS and HIV infections in Amsterdam, 1997].

Data were collected in Amsterdam in 1997 from the aids surveillance, from the HIV surveillance among pregnant women and visitors of a clinic for sexually transmitted diseases (STD), and from two 'alternative' HIV test sites, using various survey systems. The findings were compared with those of previous years. Aids was diagnosed in 1997 in 123 patients, in 194 in 1996. Of the 354 patients in whom aids was diagnosed in 1993-1997 in a hospital recording additional information, 113 patients (32%) only learned that they had an HIV infection when aids was diagnosed in them. In 1997, out of 225 pregnant women with an increased risk of HIV infection, 10 were HIV seropositive (4.4%); in 1996, this proportion was 3/285 (1.1%). Among those attending STD clinics, HIV infection was observed approximately as frequently as in earlier years: about 1% of heterosexual men and women.

Acquired Immunodeficiency Syndrome↗
PubMed1998

Adhesion molecule expression on skin endothelia in atopic dermatitis: effects of TNF-alpha and IL-4.

BACKGROUND: Atopic dermatitis (AD) is characterized by skin infiltrates of leukocytes, such as lymphocytes and eosinophils. OBJECTIVE: To describe the mechanisms determining this inflammatory process, we have analyzed expression of adhesion molecules and their regulation on skin endothelial cells (ECs). METHODS: Expression of adhesion molecules on ECs was analyzed by immunohistochemistry by using Ulex europaeus agglutin 1 as a pan-endothelial marker. RESULTS: Vascular cell adhesion molecule-1 (VCAM-1), E-selectin, and P-selectin were not found in skin of nonatopic individuals, whereas expression of these surface molecules was observed in nonlesional skin of patients with AD and was even more pronounced in lesional skin or after epicutaneous application of aeroallergen. Induction of adhesion molecule expression was examined on both macrovascular ECs from human umbilical cord vein (HUVECs) and human microvascular ECs (HMEC-1) from skin. TNF-alpha very potently upregulated adhesion molecule expression in vitro on both EC cell types. To verify the in vivo relevance of TNF-alpha, we performed TNF-alpha staining in the skin. TNF-alpha was observed in the dermis of nonatopic skin, both in chymase-containing mast cells and CD68+ macrophages. The increase in the number of TNF-alpha-containing cells was concomitant with the increase in adhesion molecule expression in the skin of patients with AD. IL-4 is supposed to be important in atopic diseases because of its IgE- and VCAM-1-inducing properties. However, IL-4 addition failed to induce VCAM-1 expression on HMEC-1, although in the same set of experiments, a clear induction of VCAM-1 expression by IL-4 on HUVECs was demonstrated. Flow cytometry revealed the absence of 11-4 receptor alpha-chains on HMEC-1 and their presence on HUVECs. Immunohistochemistry examination on skin sections showed no binding of the IL-4R alpha-chain antibodies to ECs. CONCLUSION: We conclude that adhesion molecule expression is increased in the skin of patients with AD. Most probably, this increased expression is not a (direct) effect of IL-4 on skin endothelium, but other cytokines, such as TNF-alpha, might be responsible for this increased adhesion molecule expression. Continuous adhesion molecule expression may facilitate T-cell extravasation in a nonantigen-specific manner, thus explaining the presence of increased T-cell numbers in nonlesional skin of patients with AD.

Cell Adhesion Molecules↗
PubMed1998

Prevalence and correlates of herpes simplex virus type 2 infection: evaluation of behavioural risk factors.

OBJECTIVE: To examine the prevalence and correlates of infection with herpes simplex virus type 2 (HSV-2) among sexually transmitted disease (STD) clinic attenders, we studied the prevalence of antibodies to HSV-2 and their association with risk behaviour. METHODS: Data were collected in a cross-sectional study among STD clinic attenders in Amsterdam. Seropositivity for HSV-2 was determined in 1798 serum samples by means of a monoclonal antibody-blocking enzyme-linked immunoassay. RESULTS: The prevalence of HSV-2 antibodies was higher than expected: 32.3% in a population in which 3% had current genital herpes and 8% gave a history of genital herpes. Of those with HSV-2 antibodies, only 18% had a history of genital herpes. A strong independent association with the presence of HSV-2 antibodies was found for sexual behaviour, more specifically: homosexual orientation, increasing number of years of sexual activity, increasing number of lifetime partners, number of past gonococcal infections, having receptive anal and (or) vaginal contact. CONCLUSION: The presence of HSV-2 antibodies had a strong association with past sexual behaviour and, for both sexes, with receptive anal intercourse. HSV-2 antibodies may be used as a surrogate marker of sexual risk behaviour in comparing different populations over time.

Adult↗
PubMed1997

[HIV infection and risk behaviour among prostitutes in the Amsterdam streetwalkers' district; indications of raised prevalence of HIV among transvestites / transsexuals].

OBJECTIVE: To determine the prevalence of HIV infection and risk behaviour among various groups of streetwalkers in Amsterdam and the extent of overlap between different prostitution networks. SETTING: The family room project in the streetwalkers' district in Amsterdam, the Netherlands. METHODS: In November 1996, saliva was taken from 32 female and 25 transsexual/transvestite prostitutes and tested for antibodies against HIV. Besides, prostitutes were interviewed on risk behaviour, history of sexually transmitted diseases and mobility. RESULTS: Only one of the participants (a female prostitute) had ever injected drugs. None of the female prostitutes, but 6 of the 25 transsexuals/transvestite prostitutes (24%; 95% confidence interval: 7-41) proved seropositive. None of the HIV infected participants was aware of his serostatus. The transsexual/transvestite prostitutes frequently had receptive anal intercourse with their clients. Condom use was high, but most did not use condoms made for anal intercourse. Female prostitutes also reported a high rate of condom use with their clients. Both groups of prostitutes reported few private partners and a low rate of condom use with these partners. According to the transsexual/transvestite prostitutes many of their clients had sexual contacts with women in their private lives. Many prostitutes thought that they shared the same clients in the district. CONCLUSION: HIV infections occur quite often among transsexual/transvestite prostitutes in the streetwalkers' district in Amsterdam. The risk of further spread HIV infection to their clients (and through them to other heterosexual populations) is present. AIDS education targeted at this group is important. The use of (special) condoms when having anal intercourse in private as well as in prostitution contacts should be emphatically advised.

Female↗
PubMed1997

[Little HIV risk behavior in drug users during detention in Dutch penitentiaries].

OBJECTIVE: To assess levels of HIV risk behaviour in injecting drug users during and immediately following prison terms in the Netherlands. DESIGN: Descriptive. SETTING: Municipal Health Service, Amsterdam, the Netherlands. METHODS: Injecting drug users taking part in a follow-up study on HIV infection were interviewed on injecting drug use and vaginal and anal sexual contact during their last prison term in the 3 years preceding the interview and on injecting drug use in the week following release from prison. RESULTS: A prison term in the preceding 3 years was reported by 188 (41%) of 463 interviewed drug injectors. The mean age of the 188 was 35.5 years: 146 (78%) were males, 63 (34%) had HIV antibodies, and the mean duration of latest prison term was 3.6 months. Some use of cannabis, heroin, or cocaine in prison was reported by 104 (55%), 69 (37%), and 38 (20%) respectively. Five injectors (3%) reported having injected in prison: in 4 cases once and in 1 case 3 times. No sharing of needles and syringes was reported. Vaginal or anal sex was reported by 2 (1%) of the men and none of the women. Relapse to drug injecting during the week following release from prison was reported by 78/186 (42%) participants, in most cases (34%) on the very day of release. CONCLUSION: Contrary to findings from other countries, low levels of HIV risk behaviour occur among imprisoned drug injectors in the Netherlands. Although noninjecting drug use in prison is common, drug injecting and the sharing of injecting equipment is rare. There appear to be no grounds for making clean needles and syringes available in Dutch prisons.

Adult↗
PubMed1996

HIV prevention in developed countries.

HIV prevention in developed countries is marked by impressive successes and dismal failures. The successes point the way to what works; the failures highlight obstacles that must be overcome. Successes include important behavioural changes among gay and bisexual men, antiviral use to prevent vertical transmission, and securing the safety of the blood supply. New strategies are needed to reach the residual of individuals continuing with unsafe practices (a special hazard in high-prevalence areas); to reach young people who are beginning to engage in sexual relations and injection drug use; and to overcome political opposition to prevention strategies.

Acquired Immunodeficiency Syndrome↗