Human immunodeficiency virus (HIV) infection patterns and risk behaviours in different population groups and provinces in Viet Nam

35Bulletin of the World Health Organization | January 2007, 85 (1) Objective To study patterns and determinants of HIV prevalence and risk-behaviour characteristics in different population groups in four border provinces of Viet Nam. Methods We surveyed four population groups during April–June 2002. We used stratified random-cluster sampling and collected data concomitantly on HIV status and risk behaviours. The groups included were female sex workers (n = 2023), injecting drug users (n = 1391), unmarried males aged 15–24 years (n = 1885) and different categories of mobile groups (n = 1923). Findings We found marked geographical contrasts in HIV prevalence, particularly among female sex workers (range 0–24%). The HIV prevalence among injecting drug users varied at high levels in all provinces (range 4–36%), whereas lower prevalences were found among both unmarried young men (range 0–1.3%) and mobile groups (range 0–2.5%). All groups reported sex with female sex workers. Less than 40% of the female sex workers had used condoms consistently. The strongest determinants of HIV infection among female sex workers were inconsistent condom use (adjusted odds ratio [OR], 5.3; 95% confidence interval [CI], 2.4–11.8), history of injecting drug use and mobility, and, among injecting drug users, sharing of injection equipment (adjusted OR, 7.3; 95% CI, 2.3–24.0) and sex with non-regular partners (adjusted OR 3.4; 95% CI 1.4–8.5). Conclusion The finding of marked geographical variation in HIV prevalence underscores the value of understanding local contexts in the prevention of HIV infection. Although lacking support from data from all provinces, there would appear to be a potential for sex work to drive a self-sustaining heterosexual epidemic. That the close links to serious injecting drug use epidemics can have an accelerating effect in increasing the spread of HIV merits further study. Bulletin of the World Health Organization 2007;85:35-41. Voir page 39 le résumé en français. En la página 40 figura un resumen en español. Human immunodeficiency virus (HIV) infection patterns and risk behaviours in different population groups and provinces in Viet Nam Nguyen Anh Tuan,a Knut Fylkesnes,b Bui Duc Thang,a Nguyen Tran Hien,c Nguyen Thanh Long,d Nguyen Van Kinh,d Pham Hong Thang,a Pham Duc Manhd & Nigel O’Farrell e .40 ةحفص في ةيبرعلاب صخللما لىع علاطلاا نكيم Introduction Many countries in Asia are experiencing epidemics of human immunodeficiency virus (HIV) in injecting drug users and female sex workers. These epidemics are characterized by a marked contrast in patterns of HIV transmission both within and between countries.1,2 The situation in the neighbouring countries of Cambodia, the Lao People’s Democratic Republic and Viet Nam provides a part ticular illustration of sharply contrasting epidemic patterns.3–6 In Viet Nam significant HIV epit demics have been observed among both injecting drug users and female sex workers.6 Among groups surveyed in the general population (antenatal clinic attendees, military recruits), HIV a The National Institute of Hygiene and Epidemiology, Hanoi, Viet Nam. b Centre for International Health, University of Bergen, Bergen, Norway. c Hanoi Medical School, Hanoi, Viet Nam. d AIDS Division, Ministry of Health, Hanoi, Viet Nam. e Ealing Hospital and London School of Hygiene and Tropical Medicine, London, England. Correspondence to Nigel O’Farrell (email: nigel.ofarrell@lshtm.ac.uk). Ref. No. 05-026153 (Submitted: 24 August 2005 – Final revised version received: 30 August 2006 – Accepted: 11 September 2006) prevalence has been relatively low and below 1% in all places surveyed. In these groups, however, signs of a steady rise have been observed.6–8 This evidence is based primarily on data from urban populations; little is known about the situation in rural areas, where at least 70% of the population resides. Another observation from Viet Nam is that fet male sex workers and injecting drug users are sexually linked, with female sex workers reporting injecting drug use at significant levels in some areas.6–9 As part of the intervention project Community Action for Preventing HIV/AIDS in Cambodia, Viet Nam and the Lao People’s Democratic Republic, baseline surveys were conducted in 2002 to provide a basis for shortt and longtterm evaluation.10 These surveys were designed to inform the process of interventions. The aim of this paper is to examine the baseline data from Viet Nam in this regard. We examine HIV risk distribution and determinants in different population subgroups assumed to be at higher risk of HIV infection compared with the general population. Methods We selected four border provinces for particular intervention support under the Community Action for Prevention of HIV/AIDS Project for the period 2002–2004.10 These included Lai Chau in the north and An Giang, Dong Thap and Kien Giang in the south. The surt veys targeted four different population groups, i.e. female sex workers, injecting 36 Bulletin of the World Health Organization | January 2007, 85 (1) Research HIV infection and risk behaviours in Viet Nam Nguyen Anh Tuan et al. drug users, young unmarried men aged 15–24 years and groups assumed to be highly mobile, such as border traders and fishermen. We collected informat tion about HIV status, demographic characteristics and risk behaviours. We administered a standard questionnaire during facettotface interviews. Sampling procedures We used a twotstage cluster sampling strategy. Sites chosen for sampling were in the main cities and towns and districts in areas bordering another country.10 Street-based female sex workers: The total designated was 360 per province. In the first stage, we identified locations where streettbased female sex workers were likely to be found. We randomly selected 36 locations using the probabilt ity proportional to size design method. From each location, we randomly set lected 10 streettbased female sex workers from all women present at the site at the time of the visit of the interviewing team. Karaoke-based female sex workers: The total designated was 450 per provt ince. We selected 150 sites using the probability proportional to size design method with a sampling frame that consisted of time–location clusters based on geographic sites, time of day and day of the week. We randomly selected three sex workers at each site. Injecting drug users: We selected half of the designated sample (total 360) from the available list of those registered and the other half from mapped locat tions defined as locations where injecting drug users gather and could be accessed. From a sampling frame based on a list of district communes with registered injecting drug users, we randomly set lected 15 injecting drug users. At each commune, we randomly selected 12 injecting drug users by choosing four primary respondents (index cases) from the list of registered injecting drug users. We then asked each primary respondent to lead the interviewer to two additional respondents using the “snowball techt nique”. Young men: We designated a total of 480 to be sampled per province. In each commune, we randomly selected 10 households at different places as index households. For each selected household, we listed all the people aged 15–24 years and randomly selected one for participation in the survey. The int terviewer continued visiting neighbourt ing households employing the random direction approach. The same procedure was used until we reached the total sample size. Seafarers/sea fishermen: We desigt nated a total of 480 to participate in Kien Giang province. The sampling frame consisted of all harbours and the estimated number of boats per harbour. We randomly selected 30 harbours; from each harbour, we randomly selected four boats and four people per boat. Migrant construction workers: We carried out sampling only in Lai Chau province (480 designated). The samt pling frame consisted of all houses listed under construction with an estimated measure of size. We used the probabilityt proportionalttotsize design method to select 60 clusters and then selected eight respondents from each cluster. Border traders: We sampled these in An Giang and Dong Thap. We identit fied all districts having local trade with Cambodia. We randomly selected tradt ers from roads passing close to the border until we reached a sample size of 480. Laboratory procedures We employed the HIV testing strategy III (WHO), using Determine HIV1/2 (Abbott, Tokyo, Japan) as the first test. Nontreactive tests were considered HIV antibodytnegative. We tested reactive samples again by Murex HIV1/2 (Abt bott). For samples reactive in both tests, we used Genscreen HIV1/2 (BiotRad, Marne La Coquette, France) as the third test. Sera reactive in all three tests were considered HIV antibodytpositive. For sera reactive in the first test but not in the second test, we repeated both tests. Indeterminate tests were those either remaining discordant in the second test or reactive in the first two tests but not in the third. Data analysis We analysed the data in Stata 8.0 (Stata, College Station, Texas, USA). We anat lysed HIV prevalence, type of exposure and related consistent condom use by province and subpopulation group. In An Giang, the province with a high HIV prevalence in both injecting drug users and female sex workers, a logistic regression model was established and performed separately for the two groups. Included in this model were factors either identified through a review of the literature or found to be associated with HIV infection in the bivariate analysis. For both groups, we included the following variables in the model: age, marital status, educational attainment and knowledge of own HIV status. The variables added to the model for the int jecting drug user data were type of sexual exposure (sex with female sex workers or other nontregular sex), history of sharing injection equipment and history of being in a drug rehabilitation programme. We were not able to include condom use as a variable in the analysis among injecting drug users, since information on cont dom use was collected separately by type of female sex worker. For the analysis of the female sex worker data, we included the following additional factors: category of sex worker, consistent condom use with onettime clients (i.e. always using condoms in the past month), history of injecting drug use, selftreported sexut ally transmitted infections during the past year, and mobility (having worked in other provinces). For injecting drug users, condomtuse data were collected separately by type of female sex worker contact; condom use with onettime clients was used, as this was similar to that found in regular clients. The design effect of cluster sampling was taken into account in the logistic regression models. The indicator for condom use for groups other than female sex workers was “use last time sex”, since “always in the past month” gave unstable estimates due to small numbers. Ethical aspects The study protocol was approved by the Institutional Review Board of the Nationt al Institute of Hygiene and Epidemiology in Hanoi, Viet Nam. We informed part ticipants about the purpose of the survey, the interview and HIV testing and then asked them for personal consent before the interview and venesection. HIV test results were not linked to individuals, i.e. they were unlinked anonymous. Particit pants were not given any compensation for participating in the study. Findings Distribution of HIV There were marked geographical cont trasts in the HIV prevalence (Table 1). An Giang differed from the other provt inces in terms of high HIV prevalence among both injecting drug users and female sex workers. We found high levels of HIV among injecting drug ust ers in all of the four provinces surveyed 37Bulletin of the World Health Organization | January 2007, 85 (1) Research HIV infection and risk behaviours in Viet Nam Nguyen Anh Tuan et al. (range 4–36%). Among female sex workers, the prevalence was relatively low (< 2%) in all provinces except An Giang, where the prevalence was 24.3% (95% CI, 16.1–32.3%) in streettbased female sex workers and 16.5% (95% CI, 8.9–23.9%) in karaoketbased female sex workers. In both groups of female sex workers, the highest prevalence was found in the youngest age groups (Table 2). The prevalence was relatively low in the mobile groups, except border traders in An Giang (2.1%; 95% CI, 1.0–3.8%) and Dong Thap (2.5%; 95% CI, 1.3–4.3%). Among young men, the point prevalence was below 1% in all provinces except Lai Chau (1.3%; 95% CI, 0.5–2.7%). Distribution of risk behaviour and links between population groups Injecting drug users were consistently (across provinces) linked sexually with both female sex workers and other nont regular sexual partners (data not shown). The proportion of “last time sex condom use” was less than 60% and lowest in An Giang province (38%). A consist tent finding regarding condom use in female sex workers was the particularly low use with husbands and boyfriends. Among mobile groups, female sex workt ers were the most frequent nontregular sex partners. Regardless of the mobile group category, consistent condom use with female sex workers was high but significantly lower with other nontregut lar partners and particularly low with regular partners. Among young men, sexual contacts were most frequent with a regular partner; links to nontregular partners were limited, except in two Table 1. Human immunodeficiency virus (HIV) prevalence among the surveyed population groups Population group HIV prevalence Lai Chau Kien Giang Dong Thap An Giang Street-based female sex workers 1.9 (95% CIa 0.1–9.9) (54)b 0.0 (216) 1.5 (95% CI 0.3–4.3) (201) 24.3 (95% CI 20.1–28.8) (400) Karaoke-based female sex workers 0.0 (49) 1.3 (95% CI 0.5–2.9) (449) 1.4 (95% CI 0.4–3.5) (291) 16.5 (95% CI 12.9–20.8) (363) Injecting drug users 36.1 (95% CI 31.2–41.4) (359) 23.5 (95% CI 19.4–28.0) (400) 4.0 (95% CI 2.0–7.1) (274) 13.4 (95% CI 10.1–17.4) (358) Unmarried young men 1.3 (95% CI 0.5–2.7) (480) 0.4 (95% CI 0.1–1.6) (454) 0.0 (481) 0.6 (95% CI 0.1–1.9) (470) Mobile groupsb 0.0 (478) 0.2 (95% CI 0.0–1.1) (485) 2.5 (95% CI 1.3–4.3) (480) 2.1 (95% CI 1.0–3.8) (480) a CI = confidence interval. b Figures in parentheses are the total sample size. c Mobile groups: Seafarers in Kien Giang, migrant construction workers in Lai Chau, and border traders in An Giang and Dong Thap. provinces, where contacts with female sex workers were significant (8% in An Giang and 9% in Kien Giang). Injecting drug use among female sex workers was highest (6%) in An Giang province, 4% in Lai Chau and less than 1% in the other provinces (data not shown). Mobility (i.e. female sex workers also working in other provt inces) did not differ significantly across provinces (range 15–21%; data not shown). Among young men, less than 1% reported ever having injected drugs (data not shown). The use of public sexually transmitt ted infection clinics was very low for all groups. Overall, 9.9% of female sex workers reported a sexually transmitted infection in the past 12 months; of these, 14.5% sought treatment in the public sector and 67.6% in a private clinic (data not shown). Factors associated with HIV infection among high-prevalence groups Fig. 1 summarizes sexual links between the various risk groups in An Giang, where HIV prevalence was very high among both female sex workers and injecting drug users. Among female sex workers, the strongest associations were irregular condom use, injecting drug use and mobility (data not shown). Ever havt ing injected drugs was reported by 6% of the respondents; the likelihood of HIV infection was 7.8 times higher in these respondents compared with respondents who had never injected. Consistent cont dom use with onettime clients during the past month was reported by 31% of female sex workers. The estimated likelihood of HIV infection among those who used irregular protection was 5.3 times that of those who consistently used condom (data not shown). Mobilt ity, defined as having worked in other provinces, and reported by 15%, was estimated to increase the likelihood of HIV threefold compared with nont mobile women. In the 13% of mobile women who reported having worked abroad, the HIV prevalence was 73% (data not shown). Knowledge of own HIV status, reported by 12% (18% ever tested), tended to reduce the likelihood of HIV infection (statistically significant when adjusted for age, but not in the full model). Educational attainment did not appear to be associated with HIV status (data not shown). Prominent risk factors among int jecting drug users were related to shart ing of injection equipment and sexual linkages with female sex workers and other nontregular partners (data not shown). Sharing injecting equipment was reported by 5% of the respondents, and the estimated odds in favour of HIV infection was 7.3 times that of the group that had not shared. Sexual relationships with both female sex workers and other nontregular partners (reported by 12%) appeared to increase the likelihood of int fection 3.4 times compared with injectt ing drug users reporting no nontregular sexual contacts. The likelihood of infect tion was more than three times higher among those being aware of their own HIV status (reported by 7%) versus not knowing, contrasting with the negative association in female sex workers (data not shown). Finally, being married was found to play a strong protective role, with odds in favour of infection about five times greater in those unmarried, 38 Bulletin of the World Health Organization | January 2007, 85 (1) Research HIV infection and risk behaviours in Viet Nam Nguyen Anh Tuan et al. while those with higher educational att tainment tended to be more likely to be infected with HIV. Discussion We found striking geographical differt ences in HIV prevalence between the groups studied. This is in agreement with the observations from the national HIV sentinel surveillance system, showing that HIV epidemics started at differt ent times and developed at different rates in injecting drug users and female sex workers.6–8 Several observations were indicative of close links between drugtinjectiontrelated and heterosexual epidemics. First, a substantial proportion of injecting drug users in all provinces reported recent sexual relationships with female sex workers (average, 21%; range, 9–34%) and with other nontregular and regular partners. Second, in An Giang, the only province with high HIV rates among female sex workers, sex with female sex workers and other nontregular sex partt ners appeared to be associated strongly with HIV infection among injecting drug users. Third, a notable proportion of men in mobile occupations reported sex with female sex workers during the past 30 days, whereas among young men these links were less frequent. Finally, consistent condom use was low in all groups, e.g. less than 40% of female sex workers had always used condoms with clients in the past 30 days. Several possible limitations are int volved in this baseline assessment. In several of the provinces, the total number of subjects sampled, particularly female sex workers, was low, thereby making estimates less precise and with some overlap in confidence intervals. Furthert more, the precision was also low for estimates of condom use among young men and mobile groups. The reason for this was that reported sexual contacts and related use of condoms covered a short timeframe (the past month), leading to low proportions reporting sexual contacts and thus low number of respondents. Studies suggest that underreporting the number of lifetime sexual partners is common.11 This is likely to apply to culturally inapproprit ate sexual behaviour, which is associated with stigmatization, thereby creating a social desirabilitytrelated reporting bias. Analyses of associations with and changes in selftreported sexual behaviour should therefore be interpreted with caution. The potential problem of nont response in our study was not likely to significantly bias results as it was very low in all the groups sampled. The situation in An Giang province, a border area adjacent to Cambodia, apt pears to differ from the other provinces in several ways. First, the HIV prevalence among female sex workers has been high over a long period. A survey conducted in 1995 found that 9.5% of the sampled sex workers were infected with HIV; mobility of the women and prostitution across the border was suggested as the most likely explanation for such a high prevalence at that time.12 Second, the epidemic among sex workers appears to have been established before the start of the injecting drug use epidemic. This is evidenced from HIV surveillance findt ings among injecting drug users in An Giang since 1994 showing very low HIV prevalence (< 1%) in 1994 and 1995.8 Fig. 1. Sexual networks linking sub-epidemics in An Giang FSWs 20% IDUsc 14% Regular partners Other casual partners Girlfriends Regular partners Young men 0.6%a 28% 60%b 4%b 15%8%b 10%b 53%b 13% Mobile groups 2.5% a Prevalence of human immunodeficiency virus (HIV). b Sexual contacts measured as percentage with one or more sexual contacts during the past 30 days. c IDUs = injecting drug users. d FSWs = female sex workers. Table 2. Age distribution of human immunodeficiency virus (HIV) prevalence (%) in An Giang province (total number in brackets) Population group Age group (years) Total 15–19 20–24 25–29 > 30 Street-based female sex workers 39.1 (95% CIa 27.3–50.9) (69)b 35.4 (95% CI 27.2–44.4) (127) 29.0 (95% CI 18.0–40.0) (69) 3.7 (95% CI 0.1–6.9) (135) 24.3 (95% CI 20.1–28.8) (400) Karaoke-based female sex workers 26.8 (95% CI 16.2–37.3) (71) 15.2 (95% CI 10.1–20.2) (198) 11.7 (95% CI 3.3–20.0) (60) 11.8 (95% CI 0.1–23.1) (34) 16.5 (95% CI 12.9–20.8) (363) Injecting drug users 17.1 (41) 95% CI (7.1–32.1) 18.6 (113) 95% CI (11.9–27.9) 15.7 (51) 95% CI (7.0–28.6) 7.8 (153) 95% CI (4.1–13.3) 13.4 (358) 95% CI (10.1–17.4) Unmarried young men 0.0 (251) 1.4 (95% CI 0.3–3.9) (219) No data No data 0.6 (95% CI 0.1–1.9) (470) Mobile groups 2.9 (95% CI 0.3–9.9) (70) 1.6 (95% CI 0.2–5.5) (128) 4.9 (95% CI 1.3–12.0) (82) 1.0 (95% CI 0.1–3.6) (200) 2.1 (95% CI 1.0–3.8) (480) a CI = confidence interval. 39Bulletin of the World Health Organization | January 2007, 85 (1) Research HIV infection and risk behaviours in Viet Nam Nguyen Anh Tuan et al. The comparison with the 1995 survey indicates that condom use has remained low, sharply contrasting the favourable changes observed among female sex workers in neighbouring Cambodia.3,4 Our finding of a strong independent ast sociation between “sex with nontregular partners” and HIV infection among injecting drug users suggests that sexual transmission has been an important fact tor in fuelling the epidemic in this group, i.e. there is a reciprocal relationship. It is recognized widely that HIV epidemics among injecting drug users can contribute to more generalized HIV epidemics in many settings.13 However, the effects of interventions to reduce sexual risk behaviour among injecting drug users have generally been modest.14 The degree to which epidemics among injecting drug users can contribute has been examined using different apt proaches, including mathematical modt elling of HIV transmission.15–17 Saidel et al. explored scenarios for potential HIV transmission from injecting drug users to nontinjecting sexual partners and beyond. Their model was applied to what was called a “general Asian” setting, i.e. assuming that (i) there is the potential for sex work to drive a selft sustaining heterosexual epidemic and (ii) most injecting drug users are males not involved in sex work but a substantial minority of them are clients of female sex workers.16 The model indicated that a large acceleration effect can exist between injecting drug users and female sex workers, particularly when assuming high levels of HIV among injecting drug users and still low levels among female sex workers.17 There was no evidence in our data of such a large acceleration effect. Despite very high prevalences among injecting drug users, the HIV prevalence among female sex workers was still relatively low in all provinces, except An Giang, where substantial transmission among injecting drug users started at a much later stage than among female sex workers. It should be noted that the work of Saidel et al. did not include the possible effect of injecting drug users who are sex workers.17 Injectt ing drug use among female sex workers has been reported to be high in major cities, particularly in streettbased female sex workers (e.g. Hanoi, 22%), but to be at low levels in most other areas.9,18–20 In our survey, the proportion of female sex workers having ever injected drugs was low (range < 1–6%). However, a history of drug injection and HIV infection was associated strongly, suggesting that drugt injecting female sex workers do have a high potential to accelerate heterosexual HIV epidemics. Few studies from Viet Nam have documented current sexual behaviour and existing networks of sexual mixing of males. The behaviour surveillance system covered longtdistance workers and migrant workers, and the findings correspond well with what we found among mobile groups in terms of prot portions having sex with female sex workers.9 We have documented that in most places a substantial proportion of young unmarried men have multiple sex partners and low levels of consistent condom use. However, documentation of risk behaviours among adult men is still limited. The association between “knowing own HIV status” and HIV infection was found to be negative among female sex workers but strongly positive among injecting drug users. This difference is puzzling. Access to voluntary HIV count selling and testing was insignificant in the project communities at the time of survey. In the present regression model, the association might be related to both the actual knowledge of HIV status and the “characteristic of knowing” itself. The latter has been found to be the case in the sense that HIVtinfected individuals who perceive deteriorating health tend to be more likely to seek HIV testing, leading to a positive association between HIV and knowledge of HIV.21 This project includes actions on sevt eral fronts, including behaviourtchange communication, condom promotion and targeted sexually transmitted int fection services. Our findings suggest that injecting drug users and female sex workers are the most important groups to reach in terms of prevention. In neighbouring Cambodia, prevention efforts related to sex work have generally been regarded as successful.3,4 These eft forts have been centred around a 100% condom use approach that also includes comprehensive sexually transmitted infection interventions. The low levels of condom use and high levels of gonort rhoea and chlamydia recently identified in the project provinces support the potential of this strategy.22 The findings also support giving high priority to harmtreduction programmes, including peer education, voluntary HIV counselt ling and testing, and needle and syringe exchange. Careful monitoring of outputs of such interventions in terms of covert age, intensity, acceptability and quality will be critical to inform process. O Acknowledgements The Asian Development Bank (ADB) financed the study through the Japan Community Action for Preventing HIV/AIDS Project. The authors thank all the staff at the Preventive Medicine Centers of Lai Chau, An Giang, Kien Giang and Dong Thap, other staff that participated in the survey and Peter Godwin of ADB. Competing interests: none declared. Résumé Schémas de contamination par le virus de l’immunodéficience humaine (VIH) et comportements à risque dans différents groupes de population et différentes provinces au Viet Nam Objectif Étudier les schémas de contamination par le VIH, les déterminants de la prévalence du VIH et les caractéristiques des comportements à risque dans différents groupes de population vivant dans quatre provinces frontalières du Viet Nam. Méthodes Nous avons suivi ces quatre groupes de population sur la période avril-juin 2002. Nous avons obtenu par sondage en grappes un échantillon randomisé et stratifié et également recueilli sur la même période des données sur le statut VIH et les comportements à risque. Les groupes comprenaient des professionnelles du sexe (n = 2023), des utilisateurs de drogues injectables (n = 1391), des hommes célibataires de 15 à 24 ans (n = 1885) et différentes catégories de groupes mobiles (n = 1923). Résultats Nous avons constaté des variations géographiques marquées dans la prévalence du VIH, notamment pour les professionnelles du sexe (plage : 0 - 24 %). La prévalence de ce virus chez les utilisateurs de drogues injectables était fortement variable dans les quatre provinces (plage : 4 - 36 %) et se 40 Bulletin of the World Health Organization | January 2007, 85 (1) Research HIV infection and risk behaviours in Viet Nam Nguyen Anh Tuan et al. Resumen Distribución de la infección por virus de la inmunodeficiencia humana (VIH) y comportamientos de riesgo en diferentes grupos de población y provincias de Viet Nam Objetivo Estudiar la distribución y los determinantes de la prevalencia del VIH y las características de los comportamientos de riesgo en diferentes grupos de población de cuatro provincias fronterizas de Viet Nam. Métodos Encuestamos cuatro grupos de población entre abril y junio de 2002. Utilizamos un muestreo aleatorio y estratificado por conglomerados y recogimos simultáneamente datos sobre el estado serológico y los comportamientos de riesgo. Los grupos estudiados fueron trabajadoras del sexo (n = 2023), consumidores de drogas inyectables (n = 391), varones solteros de 15 a 24 años (n = 1885) y diferentes categorías de grupos móviles (n = 1923). Resultados La prevalencia del VIH presentó grandes variaciones geográficas, en particular entre las trabajadoras del sexo (0–24%). Su prevalencia presentó grandes variaciones en todas las provincias entre los consumidores de drogas intravenosas (4–36%), y fue menor en los jóvenes solteros (0–1,3%) y los grupos móviles (0–2,5%). Todos los grupos mencionaron tener relaciones con trabajadoras del sexo, entre las cuales el uso sistemático de preservativos fue inferior al 40%. Los principales determinantes de la infección por VIH entre las trabajadoras del sexo fueron el uso no sistemático de preservativos (razón de posibilidades [odds ratio: OR] ajustada: 5,3; intervalo de confianza del 95% [IC95%]: 2,4 a 11,8), los antecedentes de consumo de drogas inyectables y la movilidad, mientras que entre los consumidores de drogas inyectables fueron el compartir el instrumental de inyección (OR ajustada: 7,3; IC95%: 2,3–24,0) y las relaciones sexuales con parejas no estables (OR ajustada: 3,4; IC95%: 1,4–8,5). Conclusión La gran variación geográfica de la prevalencia del VIH subraya la importancia del conocimiento de los contextos locales en la prevención de la infección. Aunque no todos los datos obtenidos en las diferentes provincias fueron en el mismo sentido, parece que el comercio sexual podría ser el determinante de una epidemia heterosexual autosostenida. Un tema que merece un estudio más profundo es que la estrecha relación con la grave epidemia de consumo de drogas inyectables pueda tener un efecto acelerador de la diseminación del VIH. situait à un niveau plus bas à la fois chez les hommes jeunes et célibataires (plage : 0 – 1,3 %) et les groupes mobiles (plage : 0 – 2,5 %). Dans tous les groupes, des sujets ont rapporté avoir eu des rapports sexuels avec des professionnelles du sexe. Moins de 40 % des professionnelles du sexe avaient utilisé systématiquement des préservatifs. Les plus forts déterminants de la contamination par le VIH de ces femmes étaient l’utilisation non systématique de préservatifs [odds ratio ajusté (OR) : 7,3 ; intervalle de confiance (IC) à 95 % : 2,4 – 11,8], l’existence d’antécédents d’usage de drogues injectables et de mobilité, et parmi les utilisateurs de drogues injectables, le partage du matériel d’injection (odds ratio ajusté : 7,3, IC à 95 % : 2,3 – 24,0) et les rapports avec des partenaires non réguliers (odds ratio ajusté : 3,4 ; IC à 95 % : 1,4 – 8,5). Conclusion La variation géographique marquée de la prévalence du VIH relevée dans cette étude souligne l’intérêt de comprendre les contextes locaux dans la prévention de la contamination par ce virus. Malgré l’insuffisance des données à l’appui de cette hypothèse pour les quatre provinces, il semble qu’il existe un risque que le commerce du sexe entraîne une épidémie hétérosexuelle autoentretenue. La possibilité que les liens étroits entre les fortes épidémies de toxicomanie par des drogues injectables et l’épidémie de VIH puisse accélérer la propagation de ce virus mérite d’être étudiée de manière plus poussée. صخلم مان تييف في ةفلتخم تاعطاقم فيو ةيناكس تائف ينب رطاخلماب ةفوفحلما تايكولسلاو )زديلإا( يشربلا يعانلما زَوَعلا سويرفب ىودعلا طانمأ تايكولسلا صئاصخو زديلإا سويرف راشتنا تاددحمو طانمأ ةسارد :فدهلا لىع عقت تاعطاقم عبرأ في ةفلتخم ةيناكس تائف في رطاخلماب ةفوفحلما .مان تييف في دودحلا صيقتب 2002 وينوي/ناريزح – ليربإ/ناسين ةترفلا للاخ انمق :ةقيرطلا ةيقبطلا ةقيرطلاب تانيعلا ذخأب حسلما اذه في انمقو .ةيناكس تائف عبرأ سويرف عضو نع ةيزاوم ةقيرطب تانايبلا عمجب انمقو ،ةيئاوشعلا ةيعمجتلا اياغبلا ةساردلا تائف تلمشو .رطاخلماب ةفوفحلما تايكولسلاو زديلإا روكذلاو ،)1391 مهددع( نْقَحلاب تاردخلما يطاعتمو ،)2023 نهددع( تائفو ،)1885 مهددع( ًاماع 24 – 15 ةيرمعلا ةئفلا في ينجوزتلما يرغ .)1923 مهددع( ةلقنتلما ةيناكسلا تاعومجلما نم ةفلتخم مايسلاو ،زديلإا سويرف راشتنا لدعم في حضاو فيارغج نيابت ظحول :تادوجولما سويرفلا راشتنا لدعم توافت ماك .)%24 لىإ رفص نم حوارت( اياغبلا ينب لىإ 4 نم( تاعطاقلما عيمج في ًايربك ًاتوافت نقحلاب تاردخلما يطاعتم ينب يرغ روكذلا بابشلا نم لك ينب لقأ راشتنا تلادعم تظحول ينح في ،)%36 لىإ رفص نم( ةلقنتلما ةيناكسلا تاعومجلماو )%1.3 لىإ رفص نم( ينجوزتلما تاقلاعلل مهتفراقم نع تاعومجلما عيمج نم نوكراشلما غلبأ دقو .)%2.5 نومدختسي اياغبلا نم %40 نم لقأ نأ ةساردلا تنيبو .اياغبلا عم ةيسنجلا زديلإا سويرفب ةباصلإل ةددحلما لماوعلا ىوقأ تناكو .مظتنم لكشب لزاوعلا ةح َّحصلما ةيحجرلأا ةبسن( لزاوعلا مادختسا في ماظتنلاا مدع :يه اياغبلا ينب يطاعت قباوسو ،)11.8 لىإ 2.4 نم تحوارت ذإ ،%95 ةقث ةلصاف دنع 5.3 سويرفلاب ةباصلإل ةددحلما لماوعلا ىوقأ تناكو .لقنتلاو ،نقحلاب تاردخلما ةيحجرلأا ةبسن( نقاحلما في كراشتلا يه نقحلاب تاردخلما يطاعتم ينب ةفراقمو ،)24 لىإ 2.3 نم تحوارت ذإ ،%95 ةقث ةلصاف دنع ،7.3 ةح َّحصلما ةح َّحصلما ةيحجرلأا ةبسن( تماظتنم يرغ تاكيشر عم ةيسنجلا تاقلاعلا .)8.5 لىإ 1.4 نم تحوارت ذإ ،%95 ةقث ةلصاف دنع ،3.4 راشتنا لدعم في ظوحللما فيارغجلا نيابتلا في ةلثمتلما ةجيتنلا نإ :جاتنتسلاا نم ةياقولا في ليحلما قايسلا مهف ةيمهأ لىع دكؤت ،زديلإا سويرفب ىودعلا هتاذب مئاق ءابو في ءاغبلا ةسرمام ببستت نأ لمتحلما نمو .زديلإا سويرف ضاترفلاا اذه معدي ام لىإ راقتفلاا مغرب ،ةيسنجلا ةقلاعلا قيرط نع لقتني ديزم لىإ ةجاحلا وعدت دقو .تاعطاقلما عيمج نم ةدراولا تايطعلما عقاو نم سويرف راشتنا لىع نقحلاب تاردخلما يطاعت ءابو يرثأت لوح ةساردلا نم .زديلإا 41Bulletin of the World Health Organization | January 2007, 85 (1) Research HIV infection and risk behaviours in Viet Nam Nguyen Anh Tuan et al. References 1. Walker N, Stanecki KA, Brown T, Stover J, Lazzari S, Garcia-Calleja JM, et al. Methods and procedures for estimating HIV/AIDS and its impact: the UNAIDS/WHO estimates for the end of 2001. AIDS 2003;17:2215-25. 2. UNAIDS. WHO. AIDS epidemic update: December 2005. Geneva, UNAIDS 2003.http://www.unaids.org/en/Resources/Publications/Corporate+ publications/AIDS+epidemic+update+-+December+2003.asp 3. Saphonn V, Sopheab H, Penhsun L, Vun NC, Wantha SS, Gorbach PM, et al. Current HIV/AIDS/STI epidemic: intervention programs in Cambodia, 1993–2003. AIDS Educ Prev 2004;16:64-77. 4. Sopheab H, Fylkesnes K, Vun MC, O’Farrell N. HIV-related risk behaviours in Cambodia and effects of mobility. J Acquir Immune Defic Syndr 2006; 41:81-6. 5. HIV surveillance survey and sexually transmitted infection periodic prevalence survey. Lao People’s Democratic Republic. Survey report, 2001. 6. Ministry of Health of Viet Nam. Current status of the HIV&AIDS epidemic in Vietnam December 2002. Review and analysis on data from HIV/AIDS surveillance systems and research studies. Draft report. 7. Quan VM, Chung A, Long HT, Dondero TJ. HIV in Vietnam: the evolving epidemic and the prevention response, 1996 through 1999. J Acquir Immune Defic Syndr 2000;25:360-9. 8. Nguyen TH, Hoang TL, Pham KC, van Ameijden EJ, Deville W, Wolffers I. HIV monitoring in Vietnam: system, methodology and results of sentinel surveillance. J Acquir Immune Defic Syndr 1999;21:338-46. 9. HIV/AIDS behavioral surveillance survey, Vietnam 2000. Results, Hanoi: National AIDS Standing Bureau, Family Health International, 2001. 10. Asian Development Bank. Community action for preventing HIV/AIDS. Proposed grant assistance. Financed from the Japan Fund for Poverty Reduction, to Cambodia, Lao PDR and Vietnam. JFPR: Reg 9006, April 2001. 11. Buve A, Lagarde E, Carael M, Rutenberg N, Ferry B, Glynn JR, et al. Interpreting sexual behaviour data: validity issues in the multicentre study on factors determining the differential spread of HIV in four African cities. AIDS 2001;15:S117-26. 12. Thuy NTT, Nhung VT, Thuc NV, Lien TX, Khiem HB. HIV infection and risk factors among female sex workers in southern Vietnam. AIDS 1998; 12:425-32. 13. Strathdee SA. Sexual HIV transmission in the context of injection drug use: implications for interventions. Int J Drug Policy 2003;14:79-81. 14. Vanichseni S, Des Jarlais DC, Choopanya K, Mock PA, Kitayaporn D, Sangkhum U, et al. Sexual risk reduction in a cohort of injecting drug users in Bangkok, Thailand. J Acquir Immune Defic Syndr 2004;37:1170-9. 15. Lowndes CM, Renton A, Alary M, Rhodes T, Garnett G, Stimson G. Conditions for widespread heterosexual spread of HIV in the Russian Federation: implications for research, monitoring and prevention. Int J Drug Policy 2003; 14:45-62. 16. Grassly NC, Lowndes CM, Rhodes T, Judd A, Renton A, Garnett GP. Modelling emerging HIV epidemics: the role of injecting drug use and sexual transmission in the Russian Federation, China and India. Int J Drug Policy 2003;14:25-43. 17. Saidel TJ, Jarlais DD, Peerapatanapokin W, Dorabjee J, Singh S, Brown T. Potential impact of HIV among IDUs on heterosexual transmission in Asian settings: scenarios from the Asian Epidemic Model. Int J Drug Policy 2003; 14:63-74. 18. Hien NT, Giang LT, Binh PN, Deville W, van Ameijden EJ, Wolffers I. Risk factors of HIV infection and needle sharing among injecting drug users in Ho Chi Minh City, Vietnam. J Subst Abuse 2001;13:45-58. 19. Nguyen TA, Hoang LT, Pham VQ, Detels R. Risk factors for HIV-1 seropositivity in drug users under 30 years old in Haiphong, Vietnam. Addiction 2001; 96:405-13. 20. Nguyen AT, Nguyen TH, Pham KC, Le TG, Bui DT, Hoang TL, et al. Intravenous drug use among street-based sex workers: a high-risk behaviour for HIV transmission. Sex Transm Dis 2004;31:15-9. 21. Fylkesnes K, Siziya S. A randomised trial on acceptability of voluntary HIV counselling and testing. Trop Med Int Health 2004;9:566-72. 22. Nguyen VT, Nguyen TL, Nguyen DH, Le TT, Vo TT, Cao TB, O’Farrell N. Sexually transmitted infections in female sex workers in five border provinces of Vietnam. Sex Transm Dis 2005;32:550-5.