[HIV prevalence among heterosexual subjects with multiple partners in Amsterdam]

To study the prevalence of HIV-infection among heterosexuals with multiple partners, participants were recruited from a STD clinic in Amsterdam. In 1988, 785 visitors met the selection criteria, of whom 361 (46%) finally participated. An HIV prevalence of 2/361 (0.6%) was found among participants. To test representativity, participants and refusers were compared on demographic characteristics and prevalence of STDs. Male refusers were on average younger, had on average fewer partners and relatively more often had a foreign nationality. Female refusers had on average fewer partners. No differences were found in the prevalence of STDs between participants and refusers. Because of the high refusal rate and differences between participants and refusers, the HIV prevalence found is not representative of heterosexuals with multiple partners.

HIV infection dynamics and intervention experiments in linked risk groups

A multigroup transmission model is described to study the spread of the human immunodeficiency virus (HIV) in linked risk groups. The model permits simultaneous investigation of the increase in the number of persons infected with HIV in three main risk groups: promiscuous homo/bisexual men (two levels of promiscuity), intravenous drug users (men and women) and promiscuous heterosexual men and women. Three modes of transmission are considered: anal and vaginal intercourse and needle sharing. The high dimensional parameter space is connected with the HIV incidence through a transmission matrix. This matrix summarizes the annual effective contact rates due to the three transmission modes. The model helps to clarify which data are needed to disentangle the relative contribution of the within- and between-group transmission routes. The model can be used to perform theoretical experiments. Given a specification of a baseline, the potential use of the model is illustrated by a simulation describing the effect of blocking the transmission through needle sharing. Reference is made to the HIV/AIDS epidemic in The Netherlands. The results of the study show that the model can play a part in the classification of HIV prevalence patterns in linked risk groups, in the study of the interaction between the main risk groups and in the theoretical evaluation of intervention measures.

[HIV prevalence in pregnant women in and around Amsterdam in 1989]

The HIV prevalence among pregnant women in 3 hospitals in Amsterdam was found to be 0.28% in 1988. As the population of these 3 hospitals is not representative of all pregnant women in Amsterdam, this study--which is done on a voluntary basis--in 1989 was slowly extended to all hospitals, clinics and practices of midwives. Of 5,176 pregnant women who were eligible in 1989, 4,812 (93.0%) participated in the study. Non-Dutch women were overrepresented among the refusers. Antibodies to HIV were found in 5/4, 812 women (0.10%, 95% confidence interval 0.01-0.19) and all 5 infected women reported an AIDS risk factor either for themselves or for their present or previous partner(s). Three of the infected women were only tested during the third trimester; the 2 others were tested in the first trimester of their pregnancy and underwent an abortion. The prevalence in 1989 was lower than that found in 1988 and this may have been influenced by an increased effort to counsel seropositive women--and especially intravenous drug users--on the risk of pregnancy.

Declining gonorrhoea rates in The Netherlands, 1976-88: consequences for the AIDS epidemic

The national notification gonorrhoea data are analysed over the period 1976-88 in conjunction with detailed data from the two STD clinics in Amsterdam in order to get an insight into the underlying reasons for the downward trend of gonorrhoea in The Netherlands. Possible effects of variations in reporting bias, seasonality, resistance against antibiotics, and sexual behaviour on gonorrhoea rates are considered. In 1981 the incidence of gonorrhoea started to decrease, thus preceding the onset of the AIDS epidemic in The Netherlands. Since 1983 the decline in gonorrhoea further accelerated and has been most apparent among homo- and bisexual men, presumably as a result of behavioural changes because of AIDS. There is less evidence for massive (AIDS related) behavioural changes among heterosexuals. The increasing percentage of gonorrhoea patients with recurrent episodes of STDs in Amsterdam may suggest that highly sexually active individuals continue to put themselves at risk of STDs and persist in acquiring and transmitting gonorrhoea.

Heterosexual behaviour of intravenous drug users in Amsterdam: implications for the AIDS epidemic

In order to assess the potential role of intravenous drug users (IVDUs) in Amsterdam in the heterosexual transmission of HIV, we studied the sexual behaviour of 243 male and female IVDUs with regard to their private ('steady' and 'casual') and commercial partners. The majority of the study group appear heterosexually active, especially female IVDUs, who often have commercial as well as one or more private partners. Vaginal contact is the most frequent method of sexual contact; condoms are used infrequently with private partners but much more frequently with commercial partners. A history of sexually transmitted disease is common, not only among IVDU prostitutes but also among IVDUs without a history of prostitution. IVDUs who know that they are HIV-infected reported fewer commercial partners and more frequent condom use with private partners than IVDUs who are negative or do not know their test result. We conclude that IVDUs may form an important source for heterosexual transmission of HIV. Voluntary testing of IVDUs on a large scale, together with intensive counselling, may slow down the further spread of HIV from infected IVDUs to their private and commercial partners, but is unlikely to stop heterosexual transmission completely.

[Declining trend in gonorrhea in The Netherlands; significance for the AIDS epidemic?]

Since 1981, the notified incidence of gonorrhoea has been decreasing in The Netherlands, thus preceding the onset of the AIDS epidemic. The declining trend of gonorrhoea and its underlying reasons are investigated. The reporting patterns may be influenced not only by the disease incidence but by other factors as well. Therefore the national notification gonorrhoea data over the period 1976-1988 are analysed in conjunction with detailed data from the two sexually transmitted diseases (STD) clinics in Amsterdam. Since 1983 the decline in gonorrhoea has been further reinforced by a dramatic decrease in gonorrhoea among homo/bisexual men, presumably as a result of behavioural changes because of AIDS. There is less evidence of massive behavioural changes among heterosexuals. The incidence of repeat infection among the gonorrhoea population in Amsterdam increases and may suggest that sexually highly active individuals continue to put themselves at risk of STDs, despite the educational campaigns with respect to the AIDS epidemic.

Long-term zidovudine treatment of asymptomatic HIV-1-infected subjects

Eighteen asymptomatic men with persistent human immunodeficiency virus type 1 (HIV-1) p24 antigenemia were treated with zidovudine 250-500 mg (+/- acyclovir 800 mg) 6-hourly for 4-12 weeks, and thereafter with zidovudine 500 mg (+/- acyclovir 1600 mg) 12-hourly for 92 weeks. Six additional HIV-1 p24 antigenemic subjects were treated with zidovudine 500 mg 12-hourly for 76 weeks. Disease progression occurred in 4 subjects, despite sustained reduction of serum HIV-1 p24 antigen levels: Pneumocystis carinii pneumonia was diagnosed after 60, 80, 90 and 93 weeks, respectively. The median CD4+ cell count of these 4 men at study entry was 0.2 x 10(9)/l, and it declined to 0.07 x 10(9)/l at the moment AIDS was diagnosed. In 20 subjects no disease progression occurred. The median CD4+ cell count of these 20 men at study entry was 0.4 x 10(9)/l and it was 0.45 x 10(9)/l at the end of the study period. Median serum HIV-1 p24 antigen levels at the end of the study period were 42% lower than at study entry in these 20 subjects. In 5/20 men, an initial decline was followed by a rise in antigen levels to above pretreatment value. Treatment with zidovudine was well tolerated. Anemia caused symptoms in 3/24 men, but prolonged leucopenia or neutropenia did not occur. None developed clinical or convincing biochemical evidence of zidovudine-associated myopathy.

[The epidemiology of AIDS in Amsterdam, 1982-1988]

The results are reported of AIDS monitoring in Amsterdam in the period 1982-1988. Males with homosexual contacts are the principal risk group followed by the fast-growing group of users of intravenous drugs. Transmission of the human immunodeficiency virus to the heterosexual population will occur mostly via sexual contacts with users of drugs. An investigation of the degree of underreporting in Amsterdam revealed 23 unreported patients (5.7% of the cumulative total). The median duration of survival of AIDS patients increased: 1982-1985, 9 months, 1986, 12 months, 1987, 16 months. Two-year survival of patients in the periods 1986 and 1987 was practically the same, however. It is assumed that at the end of 1991, 1124 AIDS patients domiciled in Amsterdam will have been diagnosed.

Increase of infectious syphilis among heterosexuals in Amsterdam: its relationship to drug use and prostitution

Since 1986, an increase in heterosexually acquired syphilis cases has been seen in Amsterdam. The proportion of syphilis patients who reported using hard drugs, increased from 7% in 1985 to 23% in 1988, which was mainly due to increased numbers of addicted prostitute women with syphilis.

[Prevalence and risk factors of Chlamydia trachomatis infection in clients of a venereal disease clinic in Amsterdam]

We studied the prevalence of Chlamydia trachomatis (CT) infection as well as its predictors among a sample (1000) of visitors (651 male, 349 female) of a clinic for sexually transmitted diseases (STD) in Amsterdam. The prevalence of CT was higher than that of gonorrhoea: among men, 14.3% and 11.5% and among women, 12.9% and 6.3% respectively. Independent predictors for CT infections were for men: number of leucocytes in discharge or urine, nature of urethral discharge, age and sex behavior, and in women: being warned as source or contact of a STD, age, nature of cervical discharge and bleeding from the cervical ostium after insertion of a swab. As many as 92% of the male and 81% of the female visitors of our STD clinic should be examined for CT if the presence of anyone or more of these predictors is taken as a criterion. Even then, 5% of the CT infections in women would still be missed. Based on our study results, material for the diagnosis of CT will from now on be collected routinely from all female patients of our STD clinic as well as from all males with urethritis. We advocate the expansion in the Netherlands of facilities for laboratory CT detection and its standard inclusion in STD examination.

[HIV occupational risk of surgical specialists and operating room personnel in the Saint Lucas Hospital in Amsterdam]

All instrument and needle accidents, and mucosal exposure to blood involving surgical specialists and operating room personnel were recorded for a seven-month period in a middle-sized Amsterdam hospital, the St. Lucas. Fifty-four accidents were reported, of which 42 were percutaneous wounds and 12, blood splatters in the eyes. The frequency of percutaneous wounds per operation per person ranged from 0 to 0.013. In the same period 3098 patients who had to be operated on were asked to participate in an anonymous study for HIV antibody. One hundred and twenty patients refused participation (3.9%). Of the 2978 participating patients seven were seropositive for anti-HIV (0.23%). The observed percutaneous accident frequency and HIV prevalence were used in combination with reports from the literature on the risk of infection after a single exposure to HIV infected material, to calculate the HIV professional risk for operating room personnel in this hospital. For general surgeons the risk of infection (based on 500 operations per year) was calculated as 0.0012 for an occupational lifespan of 30 years. For the other specialists and functions the risk was the same or less. Considering the low risk our conclusion is that screening of preoperative patients is not necessary in this hospital. The observance of general protective measures provides sufficient protection for the professional group examined.

[AIDS and tuberculosis; a retrospective study in 225 patients with AIDS]

Of 225 patients in whom AIDS was diagnosed in the period January 1982 to March 1988 at the Academic Medical Centre, Amsterdam, the tuberculosis incidence and the clinical and demographic characteristics were recorded retrospectively. Tuberculosis was diagnosed in 18 patients (8%). The most frequent risk factor of AIDS-tuberculosis patients was intravenous drug abuse. The chest X-ray was frequently atypical and there were more extrapulmonary locations in comparison to patients with tuberculosis without AIDS. On September 1, 1988, 13 of the 18 patients had died. The response to tuberculostatic therapy was good. Our results are in agreement with comparable studies elsewhere. The expectation is that the tuberculosis incidence among AIDS patients will increase as more intravenous drug users become part of the whole AIDS patient population.

Risk reduction among intravenous drug users in Amsterdam under the influence of AIDS

We evaluated the impact of a needle/syringe exchange program among 263 drug users in the period December 1985 to April 1988. Participants in this study were asked about their risk-behavior at three different visits. We found no increase in the proportion injecting drugs or in the frequency of intravenous drug use. A strong decrease in borrowing and lending of used needle/syringes was found and this behavioral change was not dependent on learning human immunodeficiency virus (HIV) serostatus. Although use of the exchange program increased over time, reduction in needle sharing was mainly an effect of the study with only a limited impact of the exchange program. We conclude that ample provision of needles and syringes is an important starting point but in itself not enough to produce the necessary drastic change in risk behavior. Intensive counseling of the drug user is also needed.

The impact of the needle and syringe-exchange programme in Amsterdam on injecting risk behaviour

We interviewed a group of 145 injecting drug users (IDUs) in Amsterdam about their drug use, participation in a needle-exchange programme and needle sharing. Approximately 1 year later 60 IDUs were followed up. IDUs who exchange regularly ('exchangers') are older, inject longer and are more often in contact with methadone programmes. Exchanging is associated neither with an increase in injecting nor with lending needles to other IDUs. The risk level of injecting of the exchangers is much lower than that of the non-exchangers. From this it can be concluded that a needle exchange is an effective prevention programme against the spread of HIV infection. However, efforts have to be made to reach the group of younger short-term injectors and those IDUs who are not in contact with methadone-maintenance programmes. Since there are indications that regular injectors in particular exchange, and since young male injectors are more at risk of borrowing independent of exchanging, it is argued that an exchange programme should be complemented with other prevention approaches, i.e. intensive counselling and the spread of leaflets with information on cleaning used needles with bleach.

Appearance of predictors of disease progression in relation to the development of AIDS

To study the natural history of HIV-1 infection in relation to serological and immunological profiles, 199 asymptomatic HIV-1-antibody (HIV-1-core-antibody)-seropositive and 76 seroconverted homosexual men were followed prospectively for 39 months. AIDS was diagnosed in 38 men. The AIDS attack rate was 20.8% after 39 months. The AIDS attack rate in the HIV-I-core-antibody positives was 12.1, versus 30.1% in the HIV-1-core-antibody negatives (P less than 0.001), and it was 13.3% in the HIV-1-antigen (HIV-1-Ag) negatives versus 53.9% in the HIV-1-Ag positives (P less than 0.001). The AIDS attack rate after 39 months was 10.9% in men with counts greater than or equal to 0.5 x 10(9)/l and 49.9% in those with CD4+ lymphocyte counts less than 0.5 x 10(9)/l. AIDS attack rates after 30 months in the same cohort have been previously reported [1], and were as follows: 6.8% in the core-antibody positives versus 35.7% in the core-antibody negatives. 6.9% in the HIV-1-Ag negatives versus 43.9% in the HIV-1-Ag positives, and 6.1% in those with CD4+ lymphocyte counts greater than or equal to 0.5 versus 51.9% in those with CD4+ lymphocyte counts less than 0.5 x 10(9)/l. The disappearance of core antibody, the appearance of antigen and the occurrence of low CD4+ lymphocyte counts preceded AIDS by a mean (s.d.) of 21.3 (8.9), 17.7 (8.8) and 15.7 (8.9) months, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Heterosexuals at risk for HIV: differences between private and commercial partners in sexual behaviour and condom use

To study the prevalence of HIV and other sexually transmitted diseases (STDs), sexual behaviour and condom use among heterosexuals, 193 women and 157 men entered a longitudinal study. Participants were recruited through an STD clinic, and had had five or more heterosexual partners in the preceding 6 months but had no other AIDS risk factors. Participants were divided in groups with respect to private and/or commercial sexual partners. One hundred and thirty-six (71%) women worked as prostitutes and had, on average, 115 customers a month, and 99 (63%) men had visited, on the average, eight prostitutes in the past 4 months. One hundred and seventy-one (89%) women (114 prostitutes) had had, on average, four partners, and 112 (78%) men (of whom 64 had visited prostitutes) had had, on average, seven private partners in the past 4 months. Vaginal intercourse was often or always reported by all participants whilst anal contact was seldom reported. Non-high-risk sexual techniques (for example, oro-oral, masturbation) were practised more frequently with private than with commercial partners (P less than 0.001). Although no differences were found in the frequency of practising high-risk sexual techniques (for example, vaginal, ano-genital), differences were found for frequency of condom use. Condom use during vaginal intercourse was reported more frequently with commercial than with private partners (P less than 0.01). However, if the number of partners is taken into account, prostitutes had unprotected vaginal intercourse with an estimated average number of 160 partners in 4 months, which is far more than customers (seven) and men and women with private partners only (four).(ABSTRACT TRUNCATED AT 250 WORDS)

HIV infection and STD in drug addicted prostitutes in Amsterdam: potential for heterosexual HIV transmission

To assess the potential role of drug using prostitutes in the heterosexual transmission of human immunodeficiency virus (HIV), 117 prostitutes, recruited from December 1985 to November 1987 at a weekly evening sexually transmitted diseases (STD) clinic for drug using prostitutes only, were studied for the prevalence of HIV and STD. Intravenous drug use was reported by 96 (82%) of the women. Antibody to HIV was found in 35/117 (30%) women, all but one of whom had been using drugs intravenously. Most (73, 62%) of the prostitutes reported having had more than 2000 clients each in the preceding five years. In the six months preceding enrollment to the study they had practised mainly vaginal (106/117) and orogenital (82/117) intercourse; 90% (105/117) reported frequent use of condoms in vaginal intercourse and 65% (68/105) in orogenital intercourse. Despite frequent condom use, 81% (84/104) contracted one or more STD in this period. Considering the high incidence of HIV and STD and the finding by others that the presence of STD may facilitate transmission of HIV, we conclude that the potential for HIV transmission from these prostitutes to their clients (and vice versa) was clearly present.

[The prevalence of HIV in pregnant women at 3 outpatient clinics in Amsterdam]

Pregnant women who were seen in 3 hospitals in Amsterdam were tested for antibodies to HIV, after informed consent. Out of 2,308 eligible pregnant women, 2,094 (90.7%) participated by name and 21 (0.9%) anonymously; 193 (8.4%) refused to participate. Among refusers there were significantly more women with a non-Dutch nationality or born in other countries. Of 2,115 pregnant women, 6 were found to be HIV-infected (0.28%, 95% confidence interval (0.05-0.51). Among women who at their first prenatal visit reported no AIDS-risk factor either for themselves or their partner(s), the HIV prevalence was 1/1,893 (0.05%) and among women with such risk factor the prevalence was 5/180 (2.78%). Three of the seropositive pregnant women knew before they were tested that they were HIV-infected. Of the 6 HIV-infected women one had a spontaneous abortion and the 4 women who were tested within the period when therapeutic abortion was still possible, decided to continue their pregnancy.

Association between biological properties of human immunodeficiency virus variants and risk for AIDS and AIDS mortality

49 individuals seropositive for human immunodeficiency virus (HIV) antibody were studied longitudinally for the relation between in-vitro properties of their sequential HIV isolates and clinical course before and after the development of AIDS. They were classified into three groups according to the syncytium-inducing capacity, replication rate, and host range of their HIV isolates. The most rapid progression to AIDS (median 15 months) and the lowest survival rate following AIDS diagnosis (median survival 12.5 months) were observed in individuals with high-replicating, syncytium-inducing HIV isolates, followed by individuals with high-replicating, non-syncytium-inducing isolates. In contrast, most individuals with low-replicating, non-syncytium-inducing HIV isolates remained symptom-free during the study period (median follow-up until AIDS diagnosis greater than 42 months), and the few individuals from this group in whom AIDS developed were still alive at the end of the study period (median survival greater than 34 months). In addition, AIDS patients from the three groups differed with respect to their symptoms. Zidovudine treatment in the symptom-free period seemed to delay the onset of AIDS in all risk groups, although stabilisation of CD4+ cell numbers was observed only in individuals with non-syncytium-inducing HIV variants.