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Biomedical subjects

M J van de Laar

Publications and source records attributed to M J van de Laar.

At least 19 recordsLinked to original sources
PubMed2004

[A cluster of lymphogranuloma venereum among homosexual men in Rotterdam with implications for other countries in Western Europe].

In mid-December 2003, a cluster of 15 cases of lymphogranuloma venereum (LGV) among male homosexuals was reported to the Municipal Health Service in Rotterdam by the Erasmus Medical Centre's outpatient clinic for sexually transmitted infections (STI). Most patients presented with proctitis and some with constipation. All were Caucasian and between 26 and 48 years of age. Thirteen of them were HIV-positive and eight had a concomitant STI. All men reported having had unprotected insertive and receptive anal sexual contact. Many sexual contacts were anonymous and were reported to have taken place in Germany, Belgium, the United Kingdom and France. This outbreak of LGV may extend through a large part of western Europe. In view of the patients' international contacts, international warnings and alertness are needed. Concerted action of professionals in infectious disease control and curative care is called for.

Adult↗
PubMed2003

[HIV-infection and AIDS in the Netherlands: prevalence and incidence, 1987-2001].

OBJECTIVE: To describe the results of HIV-surveillance activities in the Netherlands between 1987 and 2001. DESIGN: Descriptive. METHOD: Data were obtained from HIV-surveillance at STI-clinics, laboratory-surveillance in the region Arnhem, surveillance among injecting drug users, the AIDS-notification, STI-registration and the Amsterdam cohort studies on HIV/AIDS. RESULTS: In the Netherlands, the highest HIV-prevalences were found among injecting drug users (1-26%) and homo- and bisexual men (0-17%). In these high-risk populations, an increase in HIV-prevalence and--incidence, respectively, was found among injecting drug users in Heerlen and homosexual men (> 35 years of age) in Amsterdam. The HIV-prevalence was lower among heterosexuals in the Netherlands (0-2%). However, in certain local populations an increase was seen. In both Amsterdam and Rotterdam, the HIV-prevalence was higher in individuals tested anonymously than in those tested by name. CONCLUSION: Local increases in HIV-infections have been observed recently, in both high- and medium-risk populations.

Acquired Immunodeficiency Syndrome↗
PubMed1999

[National study of the spread of hepatitis B to provide a foundation for future vaccination policy].

On May 1st, 1999, a study was started regarding the spread of hepatitis B in the Netherlands (the so-called BRON study). For one year, data will be collected on new cases of hepatitis B with respect to transmission route, source of infection and risk factors. In addition, by use of mailed questionnaires, information on risk factors will be collected within a large group of control subjects throughout the country. The BRON study is being carried out by the National Institute for Public Health and the Environment (RIVM) in co-operation with the municipal health services and medical laboratories. The results of this study should underpin future governmental policy decisions regarding universal or selective vaccination against hepatitis B.

Female↗
PubMed1999

Assessing the sensitivity of STD surveillance in the Netherlands: an application of the capture--recapture method.

The capture-recapture method was used to estimate the sensitivity of case finding in two national STD surveillance systems: (1) STD registration at municipal health services (STD-MHS); (2) statutory notification by clinicians (NNS). To identify those cases common to both surveillance systems, cases from 1995 were compared using individual identifiers. Estimated sensitivities for syphilis were: STD-MHS 31% (95% CI: 27-35%), NNS 64% (56-71%); and for gonorrhoea: STD-MHS 15% (14-18%), NNS 22% (19-25%). The combined sensitivity of both systems was 76% for syphilis and 34% for gonorrhoea. Differences in the sensitivity of the systems were significant. The NNS was more sensitive than the STD-MHS, and the identification of cases was significantly more sensitive for syphilis than for gonorrhoea. A stratified analysis showed comparable results for the two sexes. Knowledge on the sensitivity of surveillance systems is useful for public health decisions and essential for international comparisons.

Adolescent↗
PubMed1998

[The epidemiology of hepatitis A in the Netherlands, 1957-1998].

OBJECTIVE: To describe the incidence of hepatitis A in the Netherlands, 1957-1997 to find an explanation for the increase in 1998. DESIGN: Descriptive. SETTING: National Institute of Public Health and Environment (RIVM), Bilthoven, the Netherlands. METHOD: Following an increase of the number of hepatitis A notifications in 1998 the national notification data over the period 1957-1997 were examined. The impact of waning natural immunity in the Dutch population and of the annual influx from high-endemic countries on the epidemiology of hepatitis A was studied. RESULTS: The number of notifications declined considerably in the early sixties and stabilised in the seventies at 5-7 notifications per 100,000 inhabitants. The age distribution over time showed that the proportion of cases in children is still the largest, although the proportion of notifications of adult cases increased slightly over time. A seasonal fluctuation was demonstrated by a steep increase in the number of notifications among non-Dutch children in autumn, with the infection acquired abroad, probably in Morocco or Turkey, followed by an increase among children and adults who acquired their infection in the Netherlands. The number of notifications doubled in the early months of 1998 compared with 1997. The present epidemic increase can be explained by increased transmission in subgroups who contributed similarly in the same months in the past 5 years and may result from secondary infections related to the relatively high peak in autumn in 1997. CONCLUSION: In 1975-1997 a stable but low incidence of hepatitis A was observed in the Netherlands; the number of cases among adults did not increase over time. The present epidemic increase underlines the potential risk of epidemics and the role of importation of the virus from high-endemic countries.

Adolescent↗
PubMed1998

Chlamydia trachomatis genotypes: correlation with clinical manifestations of infection and patients' characteristics.

In 1994 Chlamydia trachomatis specimens from 175 men and 135 women attending a clinic for treatment of sexually transmitted disease were genotyped by polymerase chain reaction-based restriction fragment length polymorphism of the omp1 gene. Information about the patients was collected at their initial visit. The associations between C. trachomatis genotype and patients' self-reported symptoms, clinical signs, and characteristics were studied. Genotypes E, F, and D/D-predominated (men: 71%; women: 60%). Five specimens (1.6%) showed evidence of mixed infections. Among men, complaints of urethral discharge and dysuria were most commonly associated with genotypes H and J (100% vs. 59%-68% for the other genotypes; P = .03); in addition, > or = 10 leukocytes per microscopic field were least often observed for genotypes G/Ga (19% vs. 59%-65% for the other genotypes; P = .01). Women's reports of lower abdominal pain were more often associated with F, G group genotypes (32%) than with B-complex (6%) or C-complex (13%) genotypes (P = .02). Certain symptoms of genital C. trachomatis infection were related to the infecting genotype. Further work will be necessary and should involve markers of the host immune response.

Adolescent↗
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↗
PubMed1998

Patient referral outcome in gonorrhoea and chlamydial infections.

OBJECTIVE: To describe the outcome of patient referral at the STD clinic of the University Hospital Rotterdam. To study characteristics of heterosexual index patients and partnerships related to referral outcome. METHODS: In 1994, patients with gonorrhoea and chlamydia were referred to public health nurses for interview and patient referral. Referral outcome was classified as "verified" if partners attended the STD clinic and as "believed" if partners were said to have attended elsewhere. RESULTS: Of 454 patients, 250 (55%) participated in the study. The outcome of patient referral for the 502 eligible partners was 103 (20.5%) verified referrals, 102 (20%) believed referrals, and 297 (59%) with unknown follow up. Of the 103 partners examined, 43 had an STD of which 63% reported no symptoms. The contact finding ratio was higher for chlamydia patients and heterosexual men. Also, referral was more effective for index patients with recent sexual contact, with follow up visits to the public health nurse, for men who were not commercial sex worker (CSW) clients, and, to a lesser degree, for Dutch patients and patients who sometimes used condoms. For steady partners, referral was improved if the last sexual contact was more recent. Casual partners visited the clinic more often if sexual contact occurred more than once, if the last contact was more recent, if they were older, and if they were Dutch. CONCLUSIONS: Patient referral was more effective for certain groups, such as chlamydia patients and steady partners, but was inadequate for others, including CSW and their clients, other "one night stands", young partners, and ethnic minorities.

Adult↗
PubMed1997

Different demographic and sexual correlates for chlamydial infection and gonorrhoea in Rotterdam.

BACKGROUND: The objective of the study was to estimate the prevalence of gonorrhoea and chlamydial infections and to determine sexual and demographic correlates for these sexually transmitted diseases (STD) among visitors of an STD clinic. METHODS: In 1994, a cross-sectional study was carried out among 2984 consecutive visitors of the STD clinic of the University Hospital Rotterdam. RESULTS: The prevalence of chlamydial infection was 12.1% for women and 12.3% for men. For gonorrhoea, prevalence was 3.2% and 6.0%, respectively. For men, gonorrhoea was independently associated with multiple partners in the last month, homosexual activities, a history of gonorrhoea, last sexual contact in the past 4-14 days and casual partners. In contrast, chlamydial infection was less likely to be found in homosexual men and male intravenous drug users. Additionally, chlamydial infection was independently associated with young age, multiple partners in the last 6 months and with last sexual contact in the past 2 months. For women, intravenous drug use (associated with commercial sex work) and a history of trichomoniasis were independent risk factors for gonorrhoea. Independent risk factors for chlamydial infection in women were: young age, two or three sexual partners during life and last sexual contact within 2 months. Chlamydial infection was uncommon in commercial sex workers. CONCLUSIONS: The differences in the epidemiological correlates suggest that chlamydial infection is more diffusely spread into the general population than gonorrhoea. Additionally, it is hypothesized that men acquire their chlamydial infection through less stable relationships and subsequently infect their regular female partner.

Adolescent↗
PubMed1997

Partner referral by patients with gonorrhea and chlamydial infection. Case-finding observations.

OBJECTIVE: To evaluate the outcomes of a partner referral program at the sexually transmitted disease (STD) clinic in Amsterdam that encourages gonorrhea and chlamydia patients to refer their own partners to medical examination. STUDY DESIGN: 355 patients with a confirmed infection cooperated in partner referral and gave specific details on their sexual contacts. Univariate and multivariate analyses were conducted to identify characteristics associated with the outcome of partner referral. RESULTS: The outcome of partner referral, expressed as the proportion of sex partners brought to evaluation or treatment, was 40%: 580 sex partners were identified of whom 20% attended the STD clinic, and medical follow-up could be confirmed for another 20%. No information was available for the remaining 60%. Patients with chlamydial infection referred more sexual partners than gonorrhea patients; women referred more partners than men. Sixty-three percent of the female contacts and 30% of the male contacts were found to be infected with gonorrhea, chlamydia, or both. Steady partners were more often referred by index patients than casual partners, especially if these latter were non-Dutch partners, clients of commercial sex workers, contacts met in less private settings, and "one night stands." CONCLUSIONS: Partner referral can be an effective strategy for reaching individuals at high risk for STD. The partner referral method was successful among certain populations but was inadequate for other groups. A mixed effort of provider referral in addition to partner referral may be appropriate to increase the efficacy of partner notification.

Chlamydia Infections↗
PubMed1997

Molecular epidemiology of infections with Neisseria gonorrhoeae among visitors to a sexually transmitted diseases clinic.

OBJECTIVES: To identify determinants for plasmid-mediated resistance to penicillin (penicillinase-producing Neisseria gonorrhoeae [PPNG]) and tetracycline (tetracycline-resistant N. gonorrhoeae [TRNG]) among gonococci, to determine the distribution of bacterial characteristics, and to correlate these with antibiograms and patient characteristics. STUDY DESIGN: Gonococcal isolates from 131 patients attending a sexually transmitted diseases clinic in The Netherlands in 1994 were auxotyped and serotyped and antimicrobial susceptibility was tested. Information on patient characteristics was collected at the initial visit. RESULTS: The most prevalent serotype, IB-1 (26%), proved to be related to sexual contact with casual partners, especially commercial sex partners. In addition, IB-1 strains were associated with PPNG and displayed higher minimum inhibitory concentrations (MICs) for ceftriaxone, cefuroxime, and ciprofloxacin. Homosexual men were more often infected with nonrequiring, IB-2, and IB-6 strains than heterosexuals. These strains were very sensitive to ceftriaxone and ciprofloxacin. Overall, one strain showed decreased susceptibility to ciprofloxacin (MIC 0.5 microgram/ml), but no resistance to ceftriaxone, ciprofloxacin, or cefuroxime was observed. However, 31% of the isolates were TRNG, PPNG, or both. Determinants for these resistant strains among men were the use of antibiotics (odds ratio [OR] = 4.8, 90% confidence interval [CI] 1.3-19.1), Surinam or Morrocan origin (OR = 3.3, 90% CI 1.3-8.4), and homosexual contacts (OR = 0.1, 90% CI 0.03-0.4). CONCLUSIONS: Different types, with variable susceptibility, were associated with homosexual and commercial sexual behavior. PPNG and TRNG were more commonly isolated from antibiotic users, heterosexual individuals, and ethnic minorities. Continuous surveillance of susceptibility is needed to follow the spread of PPNG and TRNG and to detect resistance to the currently recommended agents in a timely fashion.

Adolescent↗
PubMed1997

Prevalence and risk factors for hepatitis B virus infections among visitors to an STD clinic.

OBJECTIVE: To determine the prevalence and risk factors for hepatitis B virus (HBV) infections among individuals attending an STD clinic in a low endemic region. STUDY DESIGN: A total of 1228 women and 1648 men attending the STD clinic at the University Hospital Rotterdam, Netherlands, were examined for HBV infection by determination of hepatitis B surface antigen (HBsAg) and antibodies to hepatitis B core antigen (anti-HBc). Demographic characteristics, information on sexual behaviour, and intravenous drug use were recorded. RESULTS: The seroprevalence of HBsAg was 1.4% in women and 2.1% in men (0% in homosexual men). The seroprevalence of anti-HBc was 13% in women and 20% in men (36% in homosexual men). Native country, intravenous drug use, a history of STD, and the number of partners in the past half year (inversely) were independent risk factors for HBsAg positivity in women and heterosexual men. For anti-HBc independent associations were observed for native country, age, intravenous drug use, commercial sex, number of lifetime partners, homosexual contacts, orogenital contact (inverse), and a history of STD. CONCLUSION: The HBV prevalence in the STD clinic attendants was high, exceeding the national estimate, and indicates that the STD clinic population may be considered a high risk group. Our data confirmed an increased risk for HBV infections among established risk groups. Therefore, these risk groups should be routinely screened to identify HBV cases for counselling and contact tracing.

Adult↗
PubMed1997

Surveillance of antibiotic resistance in Neisseria gonorrhoeae in The Netherlands, 1977-95.

OBJECTIVE: To evaluate the prevalence and epidemiology of penicillinase producing Neisseria gonorrhoeae (PPNG) and tetracycline resistant N gonorrhoeae (TRNG) in the period 1977-95 in the Netherlands. To compare auxotypes, serovars, and antibiograms of PPNG, non-PPNG, and TRNG. To identify determinants in patient characteristics for the epidemic spread of TRNG/PPNG. METHODS: With respect to the national gonococcal surveillance all PPNG isolates from 30 laboratories over the country in 1977-90 and all gonococcal isolates from five sentinel laboratories (during 1 month per quarter) in 1991-5 were collected. Isolates were auxotyped and serotyped, the susceptibility for various antibiotics was tested and plasmid contents were evaluated. Additional data on PPNG infected individuals were collected retrospectively during a microepidemic of TRNG/PPNG. Univariate and multivariate analyses were performed to identify risk factors for TRNG/PPNG infections. RESULTS: In 1995 an overall high prevalence of PPNG infection (27%) and TRNG among PPNG infection (24%) was found in the Netherlands. Importantly, PPNG were found to have higher MICs for ceftriaxone and ciprofloxacin than non-PPNG; clinically relevant resistance to these antibiotics (or related agents) may emerge first among these strains. The observed diversity of strains (123 auxo/serovar classes since 1988) indicates a continuous introduction of new strains into the community. The epidemic increase of TRNG/PPNG was mainly caused by A/S classes NR/1B-6, PRO/1A-3, and PRO/1A-6, suggesting a clonal spread of a few strains; the rapid spread was associated with transmission in high risk individuals (that is, prostitutes and their clients). CONCLUSION: The prevalence of PPNG in the Netherlands remains high and reduced sensitivity to other antimicrobials was detected among the PPNG strains. This underlines the necessity for a continuous national surveillance of resistance in gonococci including limited epidemiological information.

Adult↗
PubMed1996

Differences in clinical manifestations of genital chlamydial infections related to serovars.

OBJECTIVES: To study the association of serovars of Chlamydia trachomatis with clinical manifestations of genital tract infection and socio-demographic characteristics. METHODS: In 1986-88 the C trachomatis isolates from 159 heterosexual men and 116 women attending a sexually transmitted disease (STD) clinic were collected and typed accordingly. A medical history was recorded, a physical examination took place and samples were taken for laboratory diagnostics. RESULTS: Serovars E, F and D were the most common for both men (75%) and women (67%). Men infected with serovars of the C-complex had more often a history of STD (p = 0.06). The opposite was demonstrated in women (p = 0.07). In addition, women younger than 18 years at first intercourse were more often infected with C-complex serovars (p = 0.05). For men, the serovars F/G less often produced symptoms of urethral discharge (p = 0.01) than the serovars of the B-complex and C-complex and were less often associated with the presence of 10 or more leukocytes in a Gram-stained smear (p = 0.04). CONCLUSIONS: In this study, infections with serovars F and G caused less obvious symptoms and signs of inflammation in men; in women no differences were found in the clinical manifestation of infections with different serovars.

Adolescent↗
PubMed1995

[Epidemic of penicillinase-producing, tetracycline-resistant gonococci; risk factors for their spread].

OBJECTIVE: To assess whether the 1989 epidemic of tetracycline-resistant (TRNG) and penicillinase-producing Neisseria gonorrhoeae (PPNG) was caused by a small number of imported strains, and what the risk factors for infection were. DESIGN: Retrospective. SETTING: The National Institute of Public Health and Environmental Protection (NIPHEP). METHOD: A total of 1257 questionnaires were sent to the 5 microbiological laboratories which had contributed most to the number of isolates sent to NIPHEP, in order to obtain additional information of all patients infected in 1989 and 1990 with PPNG. Of all these patients the results of quantitative sensitivity testing, auxotype, serotype and plasmid pattern of the PPNG were obtained. RESULTS: The questionnaire response was 1047/1257 (83.3%). A part of the isolates from the non-responders was included in the study. Determinations were performed in 1185 PPNG isolates (94.3%). In 1988 and 1989 an increase of TRNG among PPNG was observed. The PPNG isolates in 1989 (n - 472) and 1990 (n = 713) from 5 laboratories in Amsterdam. Rotterdam and The Hague, showed that the epidemic was caused mainly by the spread of three strains. NR/IB-6, PRO/IA-3 and PRO/IA-6. The introduction probably took place in The Hague in 1988 and import from abroad could not be confirmed. The TRNG risk was increased for men and women over 40 years and for men from The Hague and Rotterdam having contacts with prostitutes; the latter did not apply to Amsterdam. For women, a Turkish or Latin American nationality increased the TRNG risk. CONCLUSION: Because of the continuing threat of developing resistance and the instability of microbiological characteristics of gonococci, a continuous national surveillance is necessary, including information about risk factors for infection with resistant gonococci, to improve the control of the infection.

Adult↗
PubMed1995

Development and evaluation of screening strategies for Chlamydia trachomatis infections in an STD clinic.

OBJECTIVES: To identify predictors for Chlamydia trachomatis infection among visitors of an STD clinic in Amsterdam in 1986-1988. To design predictor-based screening programmes for C trachomatis. To evaluate the chosen screening strategy in 1993. METHODS: In 1986-1988, 947 heterosexual men and 648 women participated in the study. A medical history was recorded, a physical examination took place and samples were taken for laboratory diagnostics. Information for 1993 was available from routine databases. RESULTS: C trachomatis infections in heterosexual men in 1986-1988 (prevalence 15.8%) were independently associated with: age under 26 years, being an STD contact, coitarche below 13, last sexual contact with a non-prostitute, (muco)-purulent urethral discharge and ten or more leukocytes per microscopic field of urethral smear or urine. For women (prevalence 21.5%) independent predictors were age under 26, no history of STD, being an STD contact, cervical friability, (muco)purulent cervical discharge, presence of clue cells and ten or more leukocytes per field of urethral smear. Screening men with one anamnestic predictor for C trachomatis and ten or more leukocytes in smear or urine (59% of men) would detect 93% of the cases in 1986-1988. For females only universal screening proved to be suitable. After the introduction of a screening strategy in 1989 (universal for women, indicated by urethritis for men), a strong decline was found in the C trachomatis prevalence for all subgroups in 1993, excluding prostitute's clients and Turkish men. CONCLUSIONS: In 1993 the overall C trachomatis prevalence had declined among the attendants of the STD clinic. It seems likely that this fall was caused both by the screening programme and the reduction of risk behaviour.

Adult↗
PubMed1991

[Sexually transmissible disorders in allochtonous population groups; a pilot study].

In the registration of sexually transmitted diseases (STD) carried out by the nursing staff in the STD clinics the share of the immigrant populations of Turkish, Moroccan, Surinam and Antilles origin was investigated for the period 1986-89. In the total population of STD patients the immigrants appear to be overrepresented. Their share has increased from one-eight to one-fifth of the total number of STD cases. The STD rates (number of cases per 1000) for the Turkish and Moroccan populations are high, even after adjusting for population size and age. High STD rates are most apparent among males, especially among Turkish males. In comparison with the Dutch population more gonorrhoea is found among immigrants, in particular penicillinase producing Neisseria gonorrhoeae (PPNG). Turkish males (and prostitutes) contributed much to this relatively high prevalence. Further research is to be initiated in order to obtain better insight into the occurrence of STD among immigrant populations in The Netherlands, especially in connection with a potentially increased risk of infection with Human Immunodeficiency Virus (HIV).

Emigration and Immigration↗