[Hepatitis B virus transmission patterns in the Netherlands, 2004]. / Transmissiepatronen van hepatitis B-virus in Nederland, 2004.

OBJECTIVE: To gain insight into hepatitis B virus (HBV) transmission in the Netherlands. DESIGN: Descriptive. METHOD: During 2004, epidemiological data and blood samples (if available) were collected for all reported cases of acute HBV infections in the Netherlands. Following DNA isolation and amplification a 648 base pairs fragment of the HBV S gene was sequenced and subjected to phylogenetic analysis. The sequencing details were also linked to epidemiological information. RESULTS: In 2004, 291 cases ofacute HBV infections were reported. Blood samples were received from 171 patients (59%), and the genotype could be determined for 158 patients (54%). 6 genotypes were identified: A (64%), B (3%), C (3%), D (21%), E (5%) and F (4%). Of all patients with genotype A, 52% had been infected via homosexual or bisexual contact and 16% via heterosexual contact. Of all patients with genotype D, 42% had been infected via heterosexual contact and 15% via homosexual or bisexual contact. The genotype A cluster was extremely homogeneous with many identical sequences, while genotype B-E clusters were more heterogeneous. 4 identical sequences were found within genotype F, but the patients could not be epidemiologically linked. CONCLUSION: Sexual transmission, particularly via homosexual or bisexual contact in men, formed the most important risk factor for acquiring an acute HBV infection. Genotype A was predominant in the Netherlands, especially among homosexual or bisexual men. Most infections within genotype D occurred as a result of heterosexual contact. The results show that there was ongoing transmission of HBV in homosexual or bisexual men, while in heterosexuals more cases of new introduction were seen, possibly via chronic carriers from areas where HBV is endemic.

Population-based study on the seroprevalence of hepatitis A, B, and C virus infection in Amsterdam, 2004.

In order to enhance screening and preventive strategies, this study investigated the seroprevalence of hepatitis A, B, and C in the general adult urban population and in subgroups. In 2004, sera from 1,364 adult residents of Amsterdam were tested for viral markers. Sociodemographic characteristics were collected using a standardized questionnaire. For hepatitis A, 57.0% was immune. Of first-generation immigrants from Turkey and Morocco, 100% was immune. Of all Western persons and second-generation non-Western immigrants, approximately half was still susceptible. For hepatitis B, 9.9% had antibodies to hepatitis B core antigen (anti-HBc) and 0.4% had hepatitis B surface antigen. Anti-HBc seroprevalences were highest among first-generation immigrants from Surinam, Morocco, and Turkey, and correlated with age at the time of immigration, and among men with a sexual preference for men. Seroprevalence among second-generation immigrants was comparable to Western persons. The seroprevalence of hepatitis C virus antibodies was 0.6%. In conclusion, a country with overall low endemicity for viral hepatitis can show higher endemicity in urban regions, indicating the need for differentiated regional studies and prevention strategies. More prevention efforts in cities like Amsterdam are warranted, particularly for hepatitis A and B among second-generation immigrants, for hepatitis B among men with a sexual preference for men, and for hepatitis C. Active case finding strategies are needed for both hepatitis B and C.

Molecular epidemiology of acute hepatitis B in the Netherlands in 2004: nationwide survey.

To gain insight into hepatitis B virus (HBV) transmission in the Netherlands, epidemiological data and sera were collected from reported cases of acute HBV infections in the Netherlands in 2004. Cases were classified according to mode of transmission. A fragment of the S-gene of HBV (648 bp) was amplified, sequenced, and subjected to phylogenetic analysis. Of the 291 acute HBV cases reported in 2004, 158 (54%) were available for genotyping. Phylogenetic analysis identified 6 genotypes: A (64%), B (3%), C (3%), D (21%), E (5%) and F (5%). Of HBV infected men having sex with men, 86% were infected with genotype A, accounting for 43% of all patients infected with this genotype. There were only three reported cases of injecting drug use of which one was available for sequencing (genotype A). Unlike the genotype A cluster, sequences within the genotype B-E clusters were heterogenic. Within genotype F, several isolates had identical sequences, but patients could not be epidemiologically linked. Sexual transmission, particularly by men having sex with men was the most important transmission route for HBV. Injecting drug use plays a minor role. Genotype A is predominant in the Netherlands, especially among men having sex with men. In addition to imported strains, there seems to be a pool of related but non-identical strains circulating among chronic carriers in the migrant population, from which occasionally new patients are infected, primarily by heterosexual transmission.

Increase of sexually transmitted infections, but not HIV, among young homosexual men in Amsterdam: are STIs still reliable markers for HIV transmission?

OBJECTIVES: The incidence of HIV and STIs increased among men who have sex with men (MSM) visiting our STI clinic in Amsterdam. Interestingly, HIV increased mainly among older (> or =35 years) MSM, whereas infection rates of rectal gonorrhoea increased mainly in younger men. To explore this discrepancy we compared trends in STIs and HIV in a cohort of young HIV negative homosexual men from 1984 until 2002. METHODS: The study population included 863 men enrolled at < or =30 years of age from 1984 onward in the Amsterdam Cohort Studies (ACS). They had attended at least one of the 6 monthly follow up ACS visits at which they completed a questionnaire (including self reported gonorrhoea and syphilis episodes) and were tested for syphilis and HIV. Yearly trends in HIV and STI incidence and risk factors were analysed using Poisson regression. RESULTS: Mean age at enrollment was 25 years. The median follow up time was 4 years. Until 1995 trends in HIV and STI incidence were concurrent, however since 1995 there was a significant (p<0.05) increase in syphilis (0 to 1.4/100 person years (PY)) and gonorrhoea incidence (1.1 to 6.0/100 PY), but no change in HIV incidence (1.1 and 1.3/100 PY). CONCLUSIONS: The incidence of syphilis and gonorrhoea has increased among young homosexual men since 1995, while HIV incidence has remained stable. Increasing STI incidence underscores the potential for HIV spread among young homosexual men. However, several years of increasing STIs without HIV, makes the relation between STI incidence and HIV transmission a subject for debate.

[The 14th International Aids Conference: 'Knowledge, commitment and action']. / De 14e Internationale Aidsconferentie: 'Kennis, betrokkenheid en actie'.

During the world AIDS conference in Barcelona it became clear that the worst-case scenario of 10 years ago has become a reality: the HIV epidemic is continuing to spread. Also in industrialised countries the incidence of HIV infections among homosexual men is once again increasing. An HIV vaccine is still not available. Although the development of antiretroviral therapy continues, HIV inhibitors do not result in an eradication of HIV. It is still not clear as to when therapy can best be started and what the consequences are of temporarily withdrawing therapy. In countries where HIV inhibitors are widely available, the life expectancy of HIV-infected persons is increasing. The life expectancy of HIV patients will possibly decrease again due to an increased resistance towards the currently available antiretroviral drugs.

Decreasing STD incidence and increasing condom use among Chinese sex workers following a short term intervention: a prospective cohort study.

OBJECTIVE: To describe the impact of a repeating behavioural intervention focused on preventive education and provision of STD testing and treatment services to female sex workers. METHODS: A prospective cohort study of 966 sex workers (first of its kind in China) was conducted in Guangzhou from March 1998 to October 1999. At each visit information was collected on sexual behaviour, condom use and knowledge about HIV transmission and condom use, education was given, STD were diagnosed, and treatment was provided free of charge. We evaluated trends in condom use, knowledge about HIV transmission and condom use, and STD incidences. Generalised estimating equations were applied to control for repeated measurements. RESULTS: The proportion of consistent condom use increased from the intake through the third follow up visit (from 30% to 81%), as well as the proportion of having good knowledge on HIV transmission (4.3% to 98.6%) and condom use (23.6% to 79.3%). The incidence of gonorrhoea, trichomoniasis, and chlamydia decreased over each follow up visit; from 17.5/100 person years (PY), 22.4/100PY, 65.9/100PY at the first follow up visit to 5.1/100PY, 3.0/100PY, 16.1/100PY at the third follow up visit, for each STD respectively. CONCLUSIONS: STD care and prevention programmes targeting sex workers are feasible in China and, more importantly, intervention consisting of prevention education and STD care is likely to reduce unprotected sexual behaviour and STD incidence in this group at high risk for HIV and other STD infection.

[Syphilis epidemic and an increase of the number of HIV infections among homosexual men attending the Amsterdam venereal disease clinic]. / Syfilisepidemie en stijging van het aantal HIV-infecties onder homoseksuele mannen op de Amsterdamse SOA-polikliniek.

The registered number of cases of early infectious syphilis and of (ano)genital gonorrhoea among the attendees of the outpatient clinic for sexually transmitted diseases of the Amsterdam municipal health service shows a strong increase for both diagnoses in the period 1990-2001, notably in the last few years. Nearly all of this increase is accounted for by homosexual men. Syphilis increased mostly among men aged 35 years and over, gonorrhoea mostly among younger men. The population of older men also showed a distinct increase since 1997 in HIV incidence.

A summary report from Amsterdam: increase in sexually transmitted diseases and risky sexual behaviour among homosexual men in relation to the introduction of new anti-HIV drugs.

The worrying increase of sexually transmitted diseases (STDs) in Amsterdam was investigated in two studies carried out by the department of AIDS research of the municipal health service. The results indicate that the introduction of Highly Active Antiretroviral Therapies (HAART) may have had an influence on the increase of STDs and risky sexual behaviours in Amsterdam.