The impact of immigration on env HIV-1 subtype distribution among heterosexuals in the Netherlands: influx of subtype B and non-B strains

OBJECTIVE

To examine the epidemiological factors influencing the distribution and spread of HIV-1 subtypes among heterosexuals in the Netherlands.

METHOD

A nationwide serosurveillance in 21 HIV/AIDS centres from 1997 to 1999 involved 200 individuals for whom the mode of HIV transmission was heterosexual contact or unknown. HIV-1 subtypes were determined by phylogenetic analysis of env V3 sequences and correlated with sociodemographic characteristics of the subjects and their sexual partners.

RESULTS

HIV-1 subtype B infection occurred in 121 subjects (60%). Non-B subtypes were identified in 31 (A), 24 (C), 10 (D), six (E), four (F) and three (G) individuals; one had an unclassified subtype. The proportion of subtype B was about 60% in four of the six regions of the Netherlands, but in the Northwest and Southwest regions these proportions were 76% and 46%, respectively. The Surinamese and Antilleans, large immigrant groups, were all infected with subtype B, as were almost all individuals with an unknown source. The proportions of non-B viruses did not change significantly over time in Amsterdam, where subtyping was available from 1988 onward, but a shift in the various subtype B strains was observed, suggesting introductions of new subtype B strains in Amsterdam.

CONCLUSION

To date, HIV-1 non-B subtypes in the Netherlands are still found predominantly among heterosexuals with an epidemiological link with sub-Saharan Africa. Despite continuing introductions of non-B subtypes, the B/non-B distribution has been stable over time, most likely as a result of introductions of subtype B strains from Caribbean and South American countries.

[Roaming through methodology. XXXV. Bias in prevalent cohort studies of the natural course of disease]

The natural history of infectious diseases with a long asymptomatic incubation period has mainly been studied in cohorts of individuals already infected at study entry: the so-called prevalent cohort study. Because the time of infection is usually unknown in the prevalent cohort, in standard survival analysis it is common to use the time since entry into the cohort instead of the time since infection to study risk factors for disease progression. However, the use of the time since study entry may bias results. The two most important sources of bias are onset confounding and differential length-bias sampling. Because bias may occur, results derived from a prevalent cohort are not directly comparable to results derived from an incident cohort where the moment of infection is known.

Effects of CCR5-Delta32, CCR2-64I, and SDF-1 3'A alleles on HIV-1 disease progression: An international meta-analysis of individual-patient data

BACKGROUND

Studies relating certain chemokine and chemokine receptor gene alleles with the outcome of HIV-1 infection have yielded inconsistent results.

OBJECTIVE

To examine postulated associations of genetic alleles with HIV-1 disease progression.

DESIGN

Meta-analysis of individual-patient data.

SETTING

19 prospective cohort studies and case-control studies from the United States, Europe, and Australia.

PATIENTS

Patients with HIV-1 infection who were of European or African descent.

MEASUREMENTS

Time to AIDS, death, and death after AIDS and HIV-1 RNA level at study entry or soon after seroconversion. Data were combined with fixed-effects and random-effects models.

RESULTS

Both the CCR5-Delta32 and CCR2-64I alleles were associated with a decreased risk for progression to AIDS (relative hazard among seroconverters, 0.74 and 0.76, respectively; P = 0.01 for both), a decreased risk for death (relative hazard among seroconverters, 0.64 and 0.74; P < 0.05 for both), and lower HIV-1 RNA levels after seroconversion (difference, -0.18 log(10) copies/mL and -0.14 log(10) copies/mL; P < 0.05 for both). Having the CCR5-Delta32 or CCR2-64I allele had no clear protective effect on the risk for death after development of AIDS. The results were consistent between seroconverters and seroprevalent patients. In contrast, SDF-1 3'A homozygotes showed no decreased risk for AIDS (relative hazard for seroconverters and seroprevalent patients, 0.99 and 1.03, respectively), death (relative hazard, 0.97 and 1.00), or death after development of AIDS (relative hazard, 0.81 and 0.97; P > 0.5 for all).

CONCLUSIONS

The CCR5-Delta32 and CCR2-64I alleles had a strong protective effect on progression of HIV-1 infection, but SDF-1 3'A homozygosity carried no such protection.

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

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

Determinants of high-risk sexual behavior among immigrant groups in Amsterdam: implications for interventions

OBJECTIVES

To determine predictors for sexual risk behavior among immigrant men in Amsterdam.

METHODS

From May 1997 to July 1998, 650 men from Surinam, the Antilles, and Ghana were recruited by convenience sampling. Multivariate logistic regression was used to find independent predictors for 1) multiple sex partners (>sexual 1 partner in the past year), 2) unprotected sex with casual partners in The Netherlands, 3) sexual activity in country of origin, and 4) unprotected sex in country of origin.

RESULTS

1) Multiple sex partners were reported by 50% of respondents. Independent predictors were a recent infection with a sexually transmitted disease (STD), youth, low educational level, Afro-Surinamese origin, lack of a long-term relationship and history of commercial sex contact. 2) Unprotected sex occurred in 24% of casual partnerships. Independent predictors were a recent STD infection, low educational level, use of hard drugs, age between 20 and 29, few sexual partners, unprotected sex in country of origin, and a partner from the respondent's ethnic group. 3) During the past 5 years, 24% were sexually active in country of origin. Independent predictors were Ghanaian origin, age over 20, a relatively high income, and multiple partners. 4) Unprotected sex occurred in 39% of the partnerships in country of origin. Independent predictors were low educational level, history of STDs, lack of health insurance, Ghanaian origin, frequent visits to home country, few sexual partners, and unprotected sex with casual partners in The Netherlands.

CONCLUSION

Among immigrant men in Holland, important target groups for AIDS prevention programs have been identified. Men who visit their country of origin should be made aware of the risk of sexual contact with local women. Furthermore, it should be taken into account that immigrant men use condoms less frequently with women of their own ethnic group than with Dutch women.

[Increased Neisseria gonorrhoeae quinolone resistance in Amsterdam]

In addition to a rise in the number of cases of gonorrhoea, the susceptibility of Neisseria gonorrhoeae to antibiotics is also a cause for concern. After a period of high resistance rates to penicillin and tetracycline between 1985 and 1995, resistance rates have dropped considerably in recent years, probably due to changes in treatment regimens. However, recently we have seen an increasing number of quinolone-resistant N. gonorrhoeae isolates in Amsterdam, the Netherlands, a development that has previously been reported in other parts of the world. Some form of national resistance monitoring for gonococci is therefore urgently required to allow timely detection of changes in N. gonorrhoeae resistance.

Pneumococcal carriage in children in The Netherlands: a molecular epidemiological study

In 1999, Engelen and coworkers investigated colonization in Amsterdam among 259 children attending 16 day-care centers (DCCs) and among 276 children who did not attend day-care centers (NDCCs). A 1.6- to 3.4-fold increased risk for nasopharyngeal colonization was observed in children attending DCCs compared with NDCC children, while no difference in antibiotic resistance was found between groups. The serotype and genotype distributions of 305 nasopharyngeal Streptococcus pneumoniae isolates of the latter study were investigated. The predominant serotypes in both the DCC and the NDCC groups included 19F (19 and 18%, respectively), 6B (14 and 16%, respectively), 6A (13 and 7%, respectively), 23F (9 and 7%, respectively), and 9V (7 and 7%, respectively). The theoretical vaccine coverage of the 7-valent conjugate vaccine was 59% for the DCC children and 56% for the NDCC group. Genetic analysis of the pneumococcal isolates revealed 75% clustering among pneumococci isolated from DCC attendees versus 50% among the NDCC children. The average pneumococcal cluster size in the DCC group was 3.8 and 4.6 isolates for two respective sample dates (range, 2 to 13 isolates per cluster), while the average cluster size for the NDCC group was 3.0 (range, 2 to 6 isolates per cluster). Similar to observations made in other countries, these results indicate a higher risk for horizontal spread of pneumococci in Dutch DCCs than in the general population. This study emphasizes the importance of molecular epidemiological monitoring before, during, and after implementation of pneumococcal conjugate vaccination in national vaccination programs for children.

[Ethiopia-Netherlands AIDS research project]

The 'Ethiopia-Netherlands AIDS Research Project' (ENARP), started in 1994, is a long-term collaboration between AIDS researchers in Amsterdam and the Ethiopian Health and Nutrition Research Institute in Addis Ababa. The ENARP's primary objectives include conducting studies on HIV and AIDS in Ethiopia, especially by means of some large-scale prospective cohort studies, training Ethiopian scientists in PhD programmes in epidemiology, immunology and virology and establishing a reference laboratory for HIV and AIDS in Ethiopia and neighbouring countries. External funding for ENARP amounts to 32 million Dutch guilders for two periods of four years and is being provided by the Dutch Government. ENARP is the largest third world biomedical project supported by the Dutch Government. In 2000 two Ethiopian students obtained their doctorates from the University of Amsterdam. Five new PhD students commenced their training in 1999. ENARP hopes to set up HIV-1 vaccine phase I and phase II trials in the near future.

[Results from the 'Ethiopia-Netherlands AIDS Research Project'; 1995-2000]

Since 1995 the 'Ethiopia-Netherlands aids research project' (ENARP) has been up and running in Addis Ababa, Ethiopia. Several surveys point towards an HIV seroprevalence of approximately 15% amongst adult Ethiopians in the capital city. Prospective cohort studies initiated since early 1997 indicate that healthy, HIV negative Ethiopians have lower CD4+ T-cell counts compared to the Dutch population and in addition they have chronically activated immune systems, possibly as a result of the highly prevalent intestinal parasitic infections as well as other infections. HIV positive Ethiopians are mainly infected with HIV-1 subtype C, which can be subdivided in 2 subtypes, both of which entered Ethiopia in the early 1980's. There are considerable differences between Ethiopians and Dutch in terms of biomedical parameters relevant for HIV infection progression; these justify further efforts in future scientific research. The emphasis for this should be on robust and applicable laboratory methods, research in the field of HIV vaccine trials and information transfer to the various partners combating HIV infection/aids in Ethiopia.

Increase in sexually transmitted infections among homosexual men in Amsterdam in relation to HAART

OBJECTIVES

We investigated if a rise in rectal gonorrhoea and early syphilis among men who have sex with men (MSM) in Amsterdam coincided with the introduction of highly active antiretroviral therapies (HAART) in July 1996 and determined risk factors for these sexually transmitted infections (STI).

METHODS

Subjects were patients of the STI clinic of the municipal health service in Amsterdam. Surveillance data (1994-9) represented consultations (n=11 240) of MSM (n=6103). For analyses we used logistic regression.

RESULTS

Comparing the periods before and after the introduction of HAART, the infection rate for rectal gonorrhoea increased from 4% to 5.4% (p=.001) and for syphilis, from 0.5% to 0.8% (p = 0.050). Independent risk factors for rectal gonorrhoea (younger age, western nationality, and concurrent infection with another STI) and for early syphilis (non-western nationality and concurrent infection with rectal gonorrhoea) did not change after HAART became available. For rectal gonorrhoea, however, the infection rate increased only among men who had exclusively homosexual contacts (OR 1.38, p<0.01), compared with bisexual men. For early syphilis, the infection rate increased only among men of western nationality (OR 3.38, p<0.01) compared to men of non-western nationality.

CONCLUSIONS

Infection rates of rectal gonorrhoea and early syphilis increased, indicating a change in sexual behaviour, possibly as a result of the introduction of HAART. For now, it is important to find out how sexual behaviour is changing and to keep monitoring trends in STIs (including HIV) among MSM in Amsterdam.

The impact of harm-reduction-based methadone treatment on mortality among heroin users

OBJECTIVES

The purpose of this study was to investigate the impact of harm-reduction-based methadone programs on mortality among heroin users.

METHODS

A prospective cohort investigation was conducted among 827 participants in the Amsterdam Cohort Study. Poisson regression was used to identify methadone maintenance treatment characteristics (dosage, frequency of program attendance, and type of program) that are significantly and independently associated with mortality due to natural causes and overdose.

RESULTS

From 1985 to 1996, 89 participants died of natural causes, and 31 died as a result of an overdose. After adjustment for HIV and underweight status, there was an increase in natural-cause mortality among subjects who left methadone treatment (relative risk [RR] = 2.38, 95% confidence interval [CI] = 1.28, 4.55). Leaving treatment was also related to higher overdose mortality, but only among injection drug users (RR = 4.55, 95% CI = 1.89, 10.00).

CONCLUSIONS

Harm-reduction-based methadone treatment, in which the use of illicit drugs is tolerated, is strongly related to decreased mortality from natural causes and from overdoses. Provision of methadone in itself, together with social-medical care, appears more important than the actual methadone dosage.

Cost-effectiveness of partner pharmacotherapy in screening women for asymptomatic infection with Chlamydia Trachomatis

OBJECTIVE

To assess the cost-effectiveness of pharmacotherapy for male partners in screening women for asymptomatic infection with Chlamydia trachomatis (CT).

METHODS AND DATA

A pharmacoeconomic decision analysis model was constructed for the health outcomes of a CT screening program, such as averted cases of pelvic inflammatory disease and infertility (major outcomes). Reinfection in the absence of partner pharmacotherapy was included in the model. Cost-effectiveness from a societal perspective was estimated for prevalence data from a selective opportunistic screening program in Amsterdam. For diagnosis of asymptomatic CT infection a Ligase Chain Reaction (LCR) test on urine was used; for pharmacotherapy of women and partners azithromycin was used. By linking health outcomes with health care costs and productivity losses, averted costs were estimated. Cost-effectiveness was expressed as net costs per major outcome averted.

RESULTS

Partner pharmacotherapy reduces net costs per major outcome averted of the screening program by approximately 50%. Sensitivity analysis indicates significant improvements in cost-effectiveness of the screening program, even when relevant assumptions are varied. Within the broader framework of the screening program, partner pharmacotherapy is a cost-saving activity.

CONCLUSIONS

Inclusion of partner pharmacotherpy provides significant improvements in overall cost-effectiveness of the CT screening program among women aged 15 to 29. Partner pharmacotherapy lowers net costs per major outcome averted to the realm where implementation of the screening program should be considered. Considering the cost-saving potential, male partner pharmacotherapy should be pursued within the broader framework of a CT screening program for women. Reinfection should be included in any future pharmacoeconomic model of CT screening. Further work on this type of model should also be directed to linking cost-effectiveness to epidemiological models for the long-term spread of infectious diseases in populations.

Large decline in injecting drug use in Amsterdam, 1986-1998: explanatory mechanisms and determinants of injecting transitions

OBJECTIVES

To study community wide trends in injecting prevalence and trends in injecting transitions, and determinants.

DESIGN

Open cohort study with follow up every four months (Amsterdam Cohort Study). Generalised estimating equations were used for statistical analysis.

SETTING

Amsterdam has adopted a harm reduction approach as drug policy.

PARTICIPANTS

996 drug users who were recruited from 1986 to 1998, mainly at methadone programmes, who paid 13620 cohort visits.

MAIN RESULTS

The prevalence of injecting decreased exponentially (66% to 36% in four to six monthly periods). Selective mortality and migration could maximally explain 33% of this decline. Instead, injecting initiation linearly decreased (4.1% to 0.7% per visit), cessation exponentially increased (10.0% to 17.1%), and relapse linearly decreased (21.3% to 11.8%). Non-injecting cocaine use (mainly pre-cooked, comparable to crack) and heroin use strongly increased. Trends were not attributable to changes in the study sample.

CONCLUSIONS

Harm reduction, including large scale needle exchange programmes, does not lead to an increase in injecting drug use. The injecting decline seems mainly attributable to ecological factors (for example, drug culture and market). Prevention of injecting is possible and peer-based interventions may be effective. The consequences of the recent upsurge in crack use requires further study.

Prevalence and risk factors of HSV-1 and HSV-2 antibodies in European HIV infected women

OBJECTIVES

To investigate the prevalence and risk factors of HSV-1 and HSV-2 antibodies in HIV infected women and the association between recurrent genital ulcerations and HIV disease progression in HSV-2 positive women.

METHODS

The presence of HSV antibodies was tested in 276 of the 487 women participating in a European cohort study of HIV infected women. Prevalence rate ratios described the association between HSV infection and its risk factors, using log binomial regression. Generalised estimating equations (GEE) analysis was performed to determine the impact of markers of HIV disease progression on recurrent genital ulcerations.

RESULTS

The prevalence of HSV-1 and HSV-2 antibodies was 76% (95% confidence interval (95% CI): 71-81) and 42% (95% CI: 36-50); 30% (95% CI: 24-35) of the women had antibodies against both HSV-1 and HSV-2. The prevalence of HSV-1 was 86% (95% CI: 80-92) in southern Europe compared with 69% (95% CI: 57-79) and 67% (95% CI: 55-77) in central and northern Europe (p=0.002). This geographical variation remained after adjustment for other risk factors. An increasing number of years of sexual activity (p=0.0002) and a history of prostitution (p=0.0001) were independently associated with HSV-2 prevalence. In HSV-2 positive women, symptomatic cases of HSV infection were minimal, but increased with decreasing CD4 count.

CONCLUSION

In HIV infected women, the prevalence of HSV antibodies is high and symptomatic cases of HSV infection are minimal, but increase with decreasing CD4 count. HSV-2 but not HSV-1 was related to sexual behaviour (that is, a history of prostitution and the number of sexually active years) in this group of HIV infected women.

Sexual risk behaviour relates to the virological and immunological improvements during highly active antiretroviral therapy in HIV-1 infection

OBJECTIVES

To evaluate the effect of highly active antiretroviral therapy (HAART) on the sexual behaviour of homosexual men, we conducted (i) an ecological study of time trends in sexual behaviour and sexually transmitted diseases; (ii) a HAART-effect study focused on the practice of unprotected anogenital sex.

DESIGN

Subjects were participants in the ongoing Amsterdam Cohort Studies (ACS) among homosexual men, initiated in 1984. Data for (i) represented all ACS visits by HIV-1-positive and -negative participants who entered ACS at or below 30 years of age and were followed until 35 years (n = 1062). Data for (ii) represented all ACS visits of HIV-1-positive men from 1992 to 2000 (n = 365), of whom 84 were HAART recipients with at least 2 months of behavioural follow-up.

RESULTS

(i) After HAART became generally available in July 1996, unprotected sex was practised more frequently and the incidence of gonorrhoea was higher compared to March 1992-June 1996 among HIV-1-negative and -positive men, respectively. (ii) Among HIV-1-positive men, a higher level of unprotected sex with casual partners was observed after HIV-1 RNA became undetectable and CD4 cell counts increased with the use of HAART. Notably, in individuals who did not receive HAART, high HIV-1-RNA levels (above 10(5) copies/ml) were likewise related to unprotected sex with casual partners.

CONCLUSION

Data support the need for the reinforcement of safe sex prevention messages among HIV-1-negative men, and our data also provide a lead for redirecting and tailoring current prevention strategies to the needs of HIV-1-positive men.

Molecular epidemiology of hepatitis A virus in Amsterdam, the Netherlands

The transmission of sporadic community-acquired hepatitis A virus (HAV) among different risk groups in Amsterdam was verified by applying molecular techniques on fecal samples. These were collected in 1997/1998 from 33 persons with HAV infection that was confirmed serologically. From 8 of these persons serial stool samples were collected. Nested RT-PCR targeting the VP3-VP1 and VP1-P2a regions followed by sequence analysis established the duration of fecal HAV RNA excretion in stool and the epidemiological molecular relationships between patients. The samples of 31 patients were RT-PCR positive, of which 24 were positive for both regions. Fecal HAV shedding was found to occur for at least 33 days after onset of disease, which was the longest time span tested. Sequencing showed that the hepatitis A virus subgenotype circulating among persons from Moroccan descent (type IB) was different from the subgenotype circulating among Dutch homosexual men (type IA). If the latter is endemic in the Netherlands, its presence is of importance to the national vaccination strategy.

Using phylogenetic analysis to trace HIV-1 migration among western European injecting drug users seroconverting from 1984 to 1997

OBJECTIVE

To reconstruct the epidemiological relationships of the HIV epidemics among injecting drug users (IDU) in western Europe.

METHODS

HIV env V3 sequences of and epidemiological data were obtained from 145 IDU who seroconverted in three sequential periods: 1984-1988, 1989-1992 and 1993-1997. The sequences were phylogenetically analysed and examined for signature patterns characteristic of northern European IDU, including the conserved GGC codon in the V3 loop.

RESULTS

Subpopulations of genetically related HIV strains were observed in Italy, France, Scotland and Spain, in contrast to the Netherlands, Austria and Switzerland. This difference between the two groups of countries suggests that the HIV epidemics amongst IDU in the latter group was caused by multiple virus introductions. In Edinburgh and the surrounding area, most IDU were infected with the same GGC strain over the 12-year study period. The epidemic among IDU in north-western Europe started with GGC viruses, whereas in south-western Europe non-GGC viruses predominated. This geographical separation has faded during the course of the epidemic, most likely because of virus exchange among IDU populations.

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

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

Increased cell division but not thymic dysfunction rapidly affects the T-cell receptor excision circle content of the naive T cell population in HIV-1 infection

Recent thymic emigrants can be identified by T cell receptor excision circles (TRECs) formed during T-cell receptor rearrangement. Decreasing numbers of TRECs have been observed with aging and in human immunodeficiency virus (HIV)-1 infected individuals, suggesting thymic impairment. Here, we show that in healthy individuals, declining thymic output will affect the TREC content only when accompanied by naive T-cell division. The rapid decline in TRECs observed during HIV-1 infection and the increase following HAART are better explained not by thymic impairment, but by changes in peripheral T-cell division rates. Our data indicate that TREC content in healthy individuals is only indirectly related to thymic output, and in HIV-1 infection is mainly affected by immune activation.

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

OBJECTIVE

To determine the incidence of reported shigellosis in Amsterdam (1991-1998) and the factors related to the secondary attack rate of shigellosis.

DESIGN

Retrospective.

METHODS

From an automated data bank data were collected on all registered shigellosis patients in Amsterdam in the period 1991-1998, and their contacts found by contact tracing.

RESULTS

567 Patients with shigellosis had been reported and a Shigella infection has been diagnosed in 96 of the 983 contacts. The annual incidence decreased statistically significantly from 13 to 8/100.000. 329 males and 334 females were infected. The highest number of cases was found in children from 0-4 years and among adults from 20-34 years. Of the 663 patients 106 (16%) required hospitalization; for children under 7 this proportion was 30% (32/108). Among the contacts (excluding the 14 contacts with the same foreign source and the same first sickness day as the index patient) the secondary attack rate was 8%. Young age, of both the patient and the contact was independently related to a higher secondary attack rate.

CONCLUSION

With contact tracing for shigellosis a large number of secondary infections were found. Given the high infection rate and large number of hospitalisations among children, contact tracing should focus at this young age group.

Pre-AIDS mortality and its association with HIV disease progression in haemophilic men, injecting drug users and homosexual men

OBJECTIVE

To study pre-AIDS mortality and its association with HIV disease progression in different exposure groups with known intervals of HIV seroconversion.

DESIGN AND METHODS

The type and rate of pre-AIDS deaths were assessed in 111 HIV-infected haemophilic men followed in London, and 118 injecting drug users and 158 homosexual men followed in Amsterdam. In each group, the association between CD4+ T-cell count, HIV RNA and pre-AIDS mortality was studied using proportional hazards analysis.

RESULTS

By 10 years after seroconversion 7.3% of the haemophilic men had died without AIDS and 38.2% had developed AIDS. These figures were 20.2 and 30.5% for injecting drug users, and 8.0 and 55.0% for homosexual men. The major causes of pre-AIDS mortality appear to differ in the three exposure groups. The risk of pre-AIDS death tended to increase with decreasing CD4 cell count and increasing HIV RNA levels in injecting drug users and homosexual men. In men with haemophilia the associations were less obvious, although the log-transformed CD4 cell count was predictive for pre-AIDS death.

CONCLUSIONS

Pre-AIDS deaths occur and are at least partially related to HIV disease progression irrespective of how individuals became infected. Because of the longer life expectancy due to highly active antiretroviral therapy (HAART), pre-AIDS deaths are likely to show a further increase. Methods to incorporate these intermediate outcomes should be considered in the estimation of the size of the HIV epidemic and in the survival analysis of HIV-infected individuals. Prevention and treatment of non-AIDS infections, especially hepatitis C virus infection, and cancers will become increasingly important in HIV-infected individuals. The interaction between these therapies and HAART should be closely monitored.