Some aspects of the natural history of HIV infection

Studying factors influencing the length of the incubation period of HIV/AIDS is important to our understanding of the natural history of the disease and for the decision when to start with anti-retroviral therapy. In a multicentre study among HIV-positive homosexual men with a known date of seroconversion, we found that the median survival time after HIV infection was 12.1 years. Age is an important determinant of the survival: the older the shorter the incubation period and survival. Gender does not seem to play a role, but women appear to have higher CD4 counts than men at seroconversion, AIDS and death. HIV-positive drug users often die before they 'reach' AIDS often from HIV-related causes e.g. bacterial infections. In a multicentre study we found that such pre-AIDS mortality is now also found among homosexual men and haemophiliacs but at a much lower level. Most studies show that HIV subtype does not influence the incubation period. On the other hand genetic factors do play an important role.

T-cell progenitor function during progressive human immunodeficiency virus-1 infection and after antiretroviral therapy

Impairment of T-cell renewal has been proposed as contributing to CD4(+) T-cell depletion in persons infected with human immunodeficiency virus-1. We analyzed the T-cell development capacity of progenitors using fetal thymus organ culture. Those who progressed to AIDS had a dramatic loss in T-cell development capacity shortly after seroconversion. In contrast, long-term nonprogressors retained progenitor capacity 8 years after seroconversion. Approximately 70% of patients experienced an improvement in T-cell development capacity after receiving 6 months of potent antiretroviral therapy. Improvement in T-cell development in fetal thymus organ culture correlated with an increase in the number of naive CD4(+) T cells in peripheral blood. Numbers of progenitors in blood and bone marrow after seroconversion or during therapy did not correlate with the change observed in T-cell development capacity. These data provide evidence that HIV-1 infection can interfere with T-cell renewal at the level of the progenitor cell. Interference with T-cell renewal may contribute to CD4(+) T-cell depletion.

Strong association between failure of T cell homeostasis and the syncytium-inducing phenotype among HIV-1-infected men in the Amsterdam Cohort Study

OBJECTIVE

To assess the association between T cell homeostasis and its failure and 1.) the occurrence of AIDS and 2.) the switch from the non-syncytium-inducing (NSI) to the syncytium-inducing (SI) HIV virus phenotype.

METHODS

For each of 325 homosexual men in the Amsterdam Cohort Study, the slope of the CD3 T cell count versus time was determined. The timing (T cell inflection point (IP)) and magnitude of the change in slope were correlated with the time of the NSI/SI switch.

RESULTS

Median T cell slopes before the IP (pre-IP) were nearly zero regardless of whether AIDS occurred; the slopes after the IP (post-IP) were associated with clinical outcomes, with a median annual decline of 17.6% among those who developed AIDS and increase of 4.6% in those remaining AIDS free. Among subjects considered to have a true IP (decline > 8.2%/year post-IP), the times of the SI switch and the IP slope were highly correlated (r = 0.65); among those with AIDS, the SI switch preceded the IP by a median of 0.63 years.

CONCLUSION

These results support the concept of blind T cell homeostasis and also suggest that HIV-1 SI variants play an important role in the failure of T cell homeostasis.

High prevalence of Epstein-Barr virus type 2 among homosexual men is caused by sexual transmission

To investigate whether Epstein-Barr virus (EBV) type 2 infection is highly prevalent among homosexual men, the prevalence of EBV type 2 was studied among homosexual and heterosexual white men who were at high and low risk for sexually transmitted diseases; these data were correlated with sexual behavior. The prevalence of EBV type 2 among homosexual men was significantly higher than it was among heterosexual men (39% vs. 6%). Among high-risk heterosexual men, prevalence was significantly higher than it was among low-risk heterosexual men (15% vs. 0). In univariate analyses, EBV type 2 infection in homosexual men was significantly associated with human immunodeficiency virus (HIV) seropositivity, increased numbers of intercourse partners, non-Dutch nationality, and human herpesvirus 8 seropositivity. In multivariate analyses, an independent association with EBV type 2 was observed only for HIV seropositivity and number of sex partners. These data support the conclusion that EBV type 2 infection is more prevalent among white homosexual men and is caused by sexual transmission.

Secular trends in the survival of HIV-infected homosexual men in Amsterdam and Vancouver estimated from a death-included CD4-staged Markov model

BACKGROUND

The purpose of this study was to investigate secular trends in waiting times in CD4-based stages of human immunodeficiency virus (HIV) disease progression in two cohorts of homosexual men, one in Vancouver and one in Amsterdam. All HIV-positive men with two or more CD4 counts in their AIDS-free period between 1 January 1985 and 1 January 1997 were included in this study. Data regarding clinical AIDS diagnoses (using the 1987 Centers for Disease Control and Prevention [CDC] AIDS case definition) and death were collected through active follow-up, review of hospital records, and municipal/national registries. The Vancouver Lymphadenopathy-AIDS Study (VLAS), was started in November 1982 and had enrollment until December 1984. Both HIV-negative and HIV-positive men were followed at intervals of 3-6 months until 1986 and annually thereafter. The Amsterdam cohort study on HIV and AIDS (ACS) started in December 1984, has ongoing enrollment and follow-up of both HIV-negative and HIV-positive homosexual men. The HIV-positive men were followed at intervals of 3 months.

METHODS

The CD4-based stage of an individual at each visit was determined using smoothed data. For each cohort and in each calendar time period, a CD4-based Markov model with death as the absorbing stage was fitted to the data. The parameters in this model were estimated using the method of maximum likelihood and confidence intervals were calculated using bootstrap methods.

RESULTS

A total of 509 homosexual men participating in the VLAS were included in this study, providing 5356 visits. Some 292 men developed AIDS before 1 January 1997 and 239 died before this date. In all, 232 of the 239 deaths were AIDS related. Thirty-seven per cent of all visits were related to treatment. A total of 543 homosexual men participating in the ACS were included in this study, providing 10 043 visits; 277 men developed AIDS before 1 January 1997 and 250 died before this date. The date of AIDS diagnosis was known for 225 of the 250 deaths. Twenty per cent of all visits were related to treatment. We found that in both cohort studies the stage-specific waiting times were longer in the low CD4-based stages (stages 4, 5 and 6: i.e. CD4 count <500 cells per mm(3)) after March 1990 compared to waiting times before March 1990. The increase in mean waiting time in these stages with low CD4 count was 21%, 33% and 53%, respectively in the ACS and 20%, 2% and 29% in the VLAS. Because waiting times alone are not exclusive for progression in a reversible model we also calculated the stage-specific median incubation periods till death. Men spent considerably longer in these CD4-based stages after March 1990 compared to before March 1990.

CONCLUSIONS

Data from these population-based cohort studies showed that HIV disease progression in the calendar period where treatment was administered was slower for individuals in stages with low CD4 counts. We found no evidence for shortening of the incubation period that may have appeared from increasing virulence of the HIV in the population.

Human herpesvirus 8 infections in the Amsterdam Cohort Studies (1984-1997): analysis of seroconversions to ORF65 and ORF73

We have shown previously that human herpesvirus 8 (HHV8) seroconversion for antibodies to the latency-associated nuclear antigen encoded by ORF73 and/or the lytic capsid antigen (vp19) encoded by ORF65 is associated with orogenital contact and is strongly linked to the development of Kaposi's sarcoma among HIV-infected individuals in the Amsterdam Cohort Studies. Here, we investigate the relationship between seroconversion to these antigens and primary HHV8 infection. Between 1984 and 1997, 215 HHV8 seroconversions to ORF73 (106 cases or 49%) and/or to ORF65 (159 cases or 74%) were recorded in the cohort of homosexual men. The HHV8 seroconversion rate among HIV-infected homosexual men (6.2 per 100 person years) was consistently higher than among HIV-uninfected men (2.6 per 100 person years). In HIV-infected but not in uninfected individuals, seroconversion to ORF73/latency-associated nuclear antigen precedes that to ORF65/vp19. Antibody levels to both ORF65- and ORF73-encoded antigens were higher in HIV-infected than in HIV-uninfected men, and among HIV-seropositives, antibody levels to ORF65/vp19 rise even higher with declining CD4 cell counts and peak with Kaposi's sarcoma development, suggesting continuing and increasing viral replication. In 10.3% of HHV8 seroconversions, transient serum viremia could be demonstrated before or at seroconversion. Together with the previously reported link between unprotected orogenital sex and HHV8 seroconversion, our observations suggest that HHV8 seroconversions result from primary infections.

[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.

Epidemiology of infections with intestinal parasites and human immunodeficiency virus (HIV) among sugar-estate residents in Ethiopia

Intestinal parasitic infections could play an important role in the progression of infection with human immunodeficiency virus (HIV), by further disturbing the immune system whilst it is already engaged in the fight against HIV. HIV and intestinal parasitic infections were investigated in 1239, randomly selected individuals, aged 15-54 years, living on a sugar estate in central Ethiopia. Intestinal parasites were identified in faecal samples (one/subject) using direct, concentration, and (for Strongyloides stercoralis larvae) Baermann methods. HIV serological status was determined using ELISA, with ELISA-positive samples confirmed as positive by western blotting. Most (70.1%) of the subjects were infected with at least one intestinal parasite and 3.1% were seropositive (but asymptomatic) for HIV. The intestinal parasites identified in the study population were amoebic parasites (Entamoeba histolytica/Enta. dispar) (24.6%), hookworms (23.8%), Ascaris lumbricoides (22.2%), Trichuris trichiura (19.5%), S. stercoralis (13.0%), Taenia saginata (4.5%), Giardia lamblia (3.0%), and Enterobius vermicularis (1.3%). Overall, the HIV-positives were no more or less likely to carry intestinal parasites than the HIV-negatives (76.2% v. 69.9%; P > 0.05). However, when each parasite was considered separately, amoebic parasites were found to be more common in the HIV-positives than the HIV-negatives (43.7% v. 24.0%; P < 0.05). This difference remained significant in a multivariate analysis, after controlling for the socio-demographic characteristics of the study participants. In conclusion, there was moderate interaction between intestinal parasites and HIV at the asymptomatic stage of HIV infection. The observed association between amoebic and HIV infections requires confirmation in a prospective study, allowing for the analysis of biological mechanisms involved in the association.

Methadone maintenance and cessation of injecting drug use: results from the Amsterdam Cohort Study

AIMS

To assess relationships between characteristics of methadone maintenance treatment and long-term cessation of injecting (> or = 1 year).

DESIGN AND PARTICIPANTS

The incidence of cessation of injecting and relapse from non-injecting to injecting was estimated among 488 participants of the Amsterdam cohort study among drug users. We used a nested matched case-control design to identify methadone treatment characteristics significantly and independently related to cessation of injecting. To ensure detailed and valid assessment of methadone treatment, data of the Central Methadone Register were linked with cohort data. For 339 of 488 subjects of the initial study group methadone data were available.

FINDINGS

The incidence of cessation of injecting increased from 2.2/100 person years in 1985-89 to 5.5/100 per year in 1995-97 (Ptrend = 0.005). Relapse to injecting was high: 17.2/100 person years (no trend). Methadone dosage and frequency of methadone programme attendance in themselves were not significantly related to cessation of injecting. However, an individual increase of 5 mg or more per year (OR 4.20, 95% CI 1.54-11.46) and receiving methadone mainly via the outpatient clinic for drug-abusing prostitutes and foreigners (OR 0.18, 95% CI 0.05-0.59) were independent predictors of cessation of injecting. After cessation of injecting, there were no HIV-seroconversions during the period of non-injecting (129 person years). After relapse to injecting there was one seroconverter; however, follow-up was small (23 person years). The HIV-incidence of those who continued injecting was 3.2/100 per year.

CONCLUSIONS

Steadily increasing the methadone dosage in a harm reduction setting may be useful in supporting injecting drug users in the process of cessation of injecting and reducing the spread of HIV-infection.

[Substantial increase in gonorrhea and syphilis among clients of Amsterdam Sexually Transmitted Diseases Clinic]

In the Sexually Transmitted Diseases (STD) clinic of the Amsterdam Municipal Health Service standardized data are collected about all visitors, which makes it possible to gain insight into the STD trends. In 1999, 706 new cases of gonorrhoea and 76 new cases of infectious syphilis were diagnosed, increases of 46% and 111% respectively compared with 1998. The largest increase was seen among men who had sex with men. In this group the number of diagnosed cases of anorectal gonorrhoea in 1999 was twice as high as in 1998 (186 versus 94) and the number of infectious syphilis cases four times as high (40 versus 9). These data indicate an increase in unsafe sexual behaviour, possibly because of a change in attitudes about AIDS, now that effective antiretroviral treatment is available.

Epidemiology of HIV and Schistosoma mansoni infections among sugar-estate residents in Ethiopia

Few studies have examined the interaction between schistosomiasis and infection with human immunodeficiency virus (HIV). The overlap between the two infections, and the effect of HIV infection on the egg output and worm load of individuals co-infected with Schistosoma mansoni, were therefore investigated in a sugar estate in central Ethiopia. The 1239 subjects were selected by stratified sampling of residents aged 15-54 years. The intensities of infection with S. mansoni were measured as egg output in stools (all subjects) and as the concentration of circulating cathodic antigen (CCA) in urine (a proxy for worm load, measured in 287 subjects). Schistosome infection was detected in 358 subjects [adjusted prevalence (AP) = 31.4%] and HIV infection in 52 (AP = 3.1%). The two infections clustered into different populations of the estate: the schistosome infections were predominantly found in the camps, and primarily affected young people (aged < 20 years) and those working in the field, whereas the HIV epidemic was found in the main village, primarily affecting those aged > 20 years and those who had recently arrived on the estate. Schistosome infection was detected in 348 of the 1187 HIV-negatives (AP = 31.6%) and 10 of the 52 HIV-positives (AP = 25.1%; P > 0.05). Schistosoma mansoni egg output was significantly lower in the HIV-positives than in the HIV-negatives (Mann-Whitney test; P = 0.03; ratio of geometric means = 0.74), and remained so after controlling for potential confounders (gender, age, and residence). However, CCA concentrations (i.e. worm loads) were found to be similar for these two groups, after controlling for potential confounders (age, gender, residence, and duration of residence).

Risk factors for human herpesvirus 8 seropositivity and seroconversion in a cohort of homosexual men

Sexual and nonsexual modes of transmission of human herpesvirus 8 (HHV8) have been suggested, but specific routes remain unclear. Therefore, the objective of this study was to assess risk factors for HHV8 seropositivity and determine specific sexual practices associated with HHV8 seroconversion. Sera from 1,458 homosexual men (Amsterdam Cohort Study, 1984-1996) were tested for antibodies to HHV8 with a modified version of an enzyme immunoassay, using recombinant HHV8 lytic phase capsid (ORF65) and latent phase nuclear (ORF73) proteins. HHV8 seroprevalence at study entry was 20.9% (305/1,458); was highest among those with positive human immunodeficiency virus (HIV) status, no steady partner, and southern European or Latin American nationality; and increased with older age and higher number of sexual partners. During follow-up, 215 men seroconverted for HHV8 (incidence: 3.6/100 person-years). Both prevalence and incidence rates remained more or less stable during the study period. Orogenital insertive sex (odds ratio (OR) = 5.95; 95% confidence interval (CI): 2.88, 12.29) or orogenital receptive sex (OR = 4.29; 95% CI: 2.11, 8.71) with more than five partners in the past 6 months, older age (OR = 2.89; 95% CI: 1.13, 7.34, when older than 45 years), and preceding HIV infection (OR = 2.47; 95% CI: 1.53, 3.99) were independent predictors for HHV8 seroconversion. The authors found strong evidence for orogenital transmission of HHV8 among homosexual men.

How does tuberculosis relate to HIV positive and HIV negative drug users?

OBJECTIVES

(1) To compare the incidence of active tuberculosis in HIV positive and HIV negative drug users. (2) To describe the main characteristics of the tuberculosis cases.

DESIGN

A prospective study was performed from 1986 to 1996 as part of an ongoing cohort study of HIV infection in Amsterdam drug users.

METHODS

Data from the cohort study, including HIV serostatus and CD4-cell numbers, were completed with data from the tuberculosis registration of the tuberculosis department of the Amsterdam Municipal Health Service. Analyses were carried out with person time and survival methods.

RESULTS

Of 872 participants, 24 persons developed culture confirmed tuberculosis during a total follow up period of 4000 person years (0.60 per 100 py, 95% CI: 0.40, 0.90). Nineteen cases were HIV positive (1.54 per 100 py, 95% CI: 0.86, 2.11) and five HIV negative (0.18 per 100 py, 95% CI: 0.08, 0.43). Multivariately HIV infection (relative risk: 12.9; 95% CI: 3.4, 48.8) and age above 33 years (RR: 6.8; 95% CI: 1.3, 35.0, as compared with age below 27) increased the risk for tuberculosis substantially. Additional findings were: (1) 13 of 22 pulmonary tuberculosis cases (59%) were detected by half yearly radiographic screening of the chest; (2) tuberculosis occurred relatively early in the course of HIV infection at a mean CD4 cell number of 390/microliter; (3) an estimated two thirds of the incidence of tuberculosis observed among HIV positive cases was caused by reactivation; (4) all but one patient completed the tuberculosis treatment.

CONCLUSION

HIV infection increases the risk for active tuberculosis in Amsterdam drug users 13-fold. The incidence of tuberculosis in HIV negative drug users is still six times higher than in the overall Amsterdam population. In the absence of contact tracing and screening with tuberculin skin tests, periodic chest radiographic screening contributes substantially to early casefinding of active tuberculosis in Amsterdam drug users.

Do gender differences in CD4 cell counts matter?

OBJECTIVE

To examine the effect of gender on disease progression and whether gender differences in CD4 lymphocyte counts persisted for the entire course from HIV seroconversion until (death from) AIDS.

METHODS

CD4 lymphocyte counts were modelled in 221 female and 443 male seroconverters following seroconversion, backwards from AIDS and backwards from death using regression analysis for repeated measurements.

RESULTS

In the period before use of highly active antiretroviral therapy (HAART), progression to AIDS and to death were marginally slower in women than in men as assessed by proportional hazards analysis. Women seroconverted for HIV, developed AIDS and died at higher CD4 cell counts than men (women: 815, 146 and 44 x 10(6) cells/l, respectively; men: 727, 49 and 22 x 10(6) cells/l, respectively), although differences were only statistically significant at AIDS onset. Declines in CD4 lymphocyte counts were not significantly affected by gender and absolute differences between men and women were stable, with exception for the trajectory close to AIDS when the decline became steeper for men than women.

CONCLUSION

These gender differences in CD4 lymphocyte counts suggest a delay of initiation of therapy in women compared with men (our model predicted that women reach the threshold of starting HAART at about 12 months later than men). If this delay unfavourably influences progression, treatment guidelines should be revised so that women can benefit equally from HAART.

[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.

Long-term survival after infection with human immunodeficiency virus type 1 (HIV-1) among homosexual men in hepatitis B vaccine trial cohorts in Amsterdam, New York City, and San Francisco, 1978-1995

Information on long-term survival after infection with human immunodeficiency virus type 1 (HIV-1) is limited. In hepatitis B vaccine trials in Amsterdam, New York City, and San Francisco, 362 gay men were followed up to 18 years (1978-1995). The median survival time from seroconversion was 12.1 years (95% confidence interval: 11.4, 12.9). The annual risk of dying increased at a constant rate until 8 years after seroconversion and then leveled off, suggesting a group that is relatively resistant to progression. These data provide a picture of the natural history of HIV-1 infection, especially in the era prior to widespread use of highly effective treatments.

[Positive results from serologic screening for syphilis in pregnancy in the Amsterdam region, 1991-1995]

OBJECTIVE

To evaluate the results of screening of pregnant women for syphilis in the region of Amsterdam, the Netherlands.

DESIGN

Descriptive study and cost-benefit analysis.

METHODS

In the period 1991-1995, physicians and midwives from the Amsterdam region sent serum samples of pregnant women to the Regional Public Health Laboratory of the Municipal Health Service (GG & GD) to be screened for syphilis. All physicians who had sent in specimens with a positive result of the Treponema pallidum haemagglutination assay (TPHA) and a confirming test result were asked, in the year of the screening, by telephone or in writing, what diagnosis they had made in the woman in question. Collection of these data was handled by the social nursing staffs of the outpatient clinics for sexually transmitted diseases in Amsterdam. The costs of laboratory tests and follow-up of the children were compared with the positive effects of special treatment and education avoided by antibiotic treatment.

RESULTS

54,344 serum samples were sent in. In the city of Amsterdam the coverage was 87.4%. In 81 women (0.15%) all the serological tests for syphilis were positive. From this group, 37 women had already been treated and 24 women were treated as a result of this screening programme (most of them had a foreign nationality), 10 for early syphilis and 14 for syphilis of unknown duration, preventing the birth of an estimated five to six children with congenital syphilis. The cost-benefit ratio was 1:15.

CONCLUSION

Continuation of screening for syphilis during pregnancy in the Amsterdam region remains useful.

HIV prevalence, sexual risk behaviour and sexual mixing patterns among migrants in Amsterdam, The Netherlands

OBJECTIVE

To study (1) HIV prevalence; (2) sexual risk behaviour; (3) sexual mixing patterns; (4) determinants of disassortative (between-group) mixing among migrant groups in Amsterdam, the Netherlands and to gain insight into the potential for heterosexual spread of HIV/sexually transmitted diseases.

DESIGN

Cross-sectional study among 1660 Surinamese, Antilleans and sub-Saharan Africans, mainly recruited on the streets.

METHODS

Saliva was tested for HIV and questions were asked about sociodemographic characteristics, sexual behaviour and the ethnicity of sexual partners. Multivariate logistic regression analysis was used to find predictors for disassortative mixing.

RESULTS

HIV prevalence was 1.1% (95% confidence interval: 0.6-1.7). Compared with the Dutch population in general, our study group reported having multiple partners, concurrent partnerships and a history of sexually transmitted diseases much more frequently. Sex in the country of origin during a visit occurred frequently and there was a considerable degree of sexual mixing between different ethnic groups in the Netherlands. For men, disassortative mixing was associated with hard drug use, recent immigration, a high number of partners, being from Nigerian or Hindu-Surinamese origin, a recent sexually transmitted disease and, for steady relationships, consistent condom use. For women, determinants included: hard drug use, low income, being a-religious and, for Antillean and Ghanaian women, consistent condom use.

CONCLUSION

Our data suggest a potential for heterosexual spread of sexually transmitted diseases within and between ethnic groups in the Netherlands. The potential for HIV spread is however limited by the low HIV prevalence at present among these groups. This situation may change when HIV prevalence increases in the countries of origin, as bridges exist between those countries and the Netherlands. Culturally appropriate AIDS prevention programmes remain important for these groups.

Methadone maintenance treatment modalities in relation to incidence of HIV: results of the Amsterdam cohort study

STUDY OBJECTIVE

To evaluate methadone maintenance treatment modalities, prescribed within the concept of harm reduction, in relation to incidence of HIV infection among drug users with a history of methadone treatment in Amsterdam, The Netherlands.

DESIGN

Prospective observational cohort study among 582 HIV-negative drug users. To ensure valid and detailed assessment of methadone treatment, data from the Central Methadone Register in Amsterdam were linked to the Amsterdam cohort study among drug users.

METHODS

Poisson regression analysis was used to identify independent and significant predictors of incidence of HIV.

MAIN RESULTS

During 1906 person years, 58 drug users seroconverted, the overall incidence of HIV being 3.0 per 100 person years with a declining trend for current injectors. An increase in frequency of methadone programme attendance [relative risk (RR), 2.4; 95% confidence interval (CI), 1.2-4.6, compared with no change] and increase in methadone dosage (RR, 0.8; 95% CI, 0.6-1.0, per category of change of 10 mg/day) were significantly associated with incidence of HIV in multivariate analysis. Methadone dosage and frequency of programme attendance in itself were not significant predictors. Other multivariate significant risk factors were homelessness, current injecting and in-patient hospital care.

CONCLUSIONS

Among drug users who receive methadone maintenance treatment in a harm-reduction setting, which includes ancillary services such as needle-exchange programmes and HIV testing and counselling, prescription of high methadone dosages is not sufficient to stop the spread of HIV. However, an individual increase of the methadone dosage and measures to achieve high treatment retention could contribute to the prevention of HIV among drug users.

Lymphoproliferative response to HIV type 1 p24 in long-term survivors of HIV type 1 infection is predictive of persistent AIDS-free infection

To establish immunologic correlates of progression to AIDS in long-term survivors of HIV-1 infection, HIV-1-specific T cell-mediated responses, together with T cell reactivity to recall antigens, were studied in frozen samples collected after 5 and 8 years of documented HIV-1 infection. Eight of 21 homosexual men, who remained asymptomatic and maintained CD4+ T cell numbers >400 cells/microl for 9 years of HIV-1 infection, progressed to AIDS (CDC 1993 definition) within 12.5 years of infection (late progressors, LPs). The remainders showed minimal deterioration of immune parameters (long-term nonprogressors, LTNPs). CD4+ T cell numbers and T cell function measured at years 5 and 8 of follow-up were comparable in the two groups. At both time points responses to recall antigens did not significantly differ between the two groups, although a significant decline of lymphoproliferative responses to Candida and tetanus toxoid was observed in LPs. Circulating HIV-1-specific cytotoxic T lymphocyte precursors were found in broad frequency ranges in both LPs and LTNPs and, similarly, no significant differences were found in comparing the breadth of serum neutralizing activity against heterologous HIV-1 primary isolates. In contrast, lymphoproliferative responses to p24gag, but not p17gag or gp160env, were detected only in LTNPs and were totally absent in LPs at both time points (p < 0.01). Our data suggest that the presence of circulating p24-specific CD4+ T cells may reflect effective viral control and be predictive of subsequent favorable clinical course in long-term asymptomatic individuals.

Sexual behaviours, perception of risk of HIV infection, and factors associated with attending HIV post-test counselling in Ethiopia

OBJECTIVES

To describe sexual behaviours, perception of risk of HIV infection, and factors associated with attending HIV post-test counselling (PTC) among Ethiopian adults.

METHODS

Data on socio-demographic characteristics, knowledge of HIV infection, sexual history, medical examination, and HIV and syphilis serological status were compared, through uni- and multivariate analysis, in relation to attending PTC within 60 days of HIV testing.

RESULTS

Between February 1997 and June 1998, 751 factory workers were enrolled in a cohort study of HIV infection progression. Despite reporting high-risk sexual behaviours, mainly for males (64% of males and 6% of females had more than five sexual partners in their lifetime, 16% of males and 2% of females reported having had recent casual partners), and knowing that HIV is commonly transmitted heterosexually in Ethiopia (97% of answers being correct, both genders combined), only 17% of males and 2% of females acknowledged having had activities which had put them at risk of HIV infection. HIV prevalence was 12%, and did not differ by gender. Of all study participants, 327 (43.5%) returned for PTC within 60 days of HIV testing. PTC attendance did not differ by age, gender, or HIV serological status. Factors independently associated with PTC attendance in males were: good knowledge of HIV infection, [odds ratio (OR) = 1.661, belief that medical follow-up improves the course of HIV infection (OR = 2.02), history of genital symptoms (OR = 2.83), positive syphilis serology (OR = 2.62), recent weight loss (OR = 1.89), and, with a negative association, being a manual worker (OR = 0.40), and history of recent casual sexual relationships (OR = 0.35). In women, belief that HIV/AIDS can be cured (OR = 3.16), never having been married (OR = 5.02), having five or less children (OR = 2.16), having been raped (OR = 3.42), and having used health facilities in the past year (OR = 1.73) were all positively and independently associated with PTC attendance.

CONCLUSION

Study participants reported high-risk sexual behaviours, yet had a low perception of individual risk. Men attended for PTC because of their knowledge of HIV infection, their past sexual history or their current health status. Women attended for PTC because of their plans for the future, marriage and/or children, rather than their past sexual exposure. Only in cases of rape were they willing to learn of their HIV status.

Dose-effect relationship between overdose mortality and prescribed methadone dosage in low-threshold maintenance programs

The present study evaluates the effectiveness of low-threshold methadone maintenance in reducing overdose mortality. In a prospective cohort study conducted in Amsterdam, 498 Dutch injecting drug users (IDU) provided 1,969 person years of follow-up (1989-1995). Forty-four IDU died in this period, 15 due to illicit drug overdose. Compared to IDU not in maintenance, the adjusted relative risk for overdose mortality among those receiving 5-50 mg, 55-70 mg, and 75+ mg were 0.35, 0.13, and 0.11, respectively (p < .05). Also current injection use and HIV-seropositivity were independent predictors for overdose mortality. Whereas previous studies indicated effectiveness of methadone-assisted detoxification and high-dose maintenance programs in reducing mortality, the present study findings suggest that low-threshold maintenance programs also reduce overdose mortality, with higher dosages being most protective.