HIV prevalence and factors associated with HIV infection among male injection drug users under 30: a cross-sectional study in Long An, Vietnam

The HIV Sentinel Surveillance in Vietnam shows that HIV infection has reached epidemic proportions among injection drug users (IDUs) [1–3]. The observed higher risk of IDUs has been explained by the combination of different risk behaviors such as sharing of syringes and needles, no regular use of condoms, and contact with different sexual partners [4]. Actually, IDUs in general are known to be sexually active [5], and male IDUs who had sexual contacts with female sex workers (FSWs) reportedly have a higher HIV infection risk than IDUs who do not [6, 7]. Because the sheer scale of problems involving IDUs and IDU-related HIV infection is far greater in developing and transitional countries [3, 8], assessment of the behavioral risks of male IDUs for both themselves and other population including women and children is highly important, and urgently needed especially in Vietnam, where there is little information about this issue compared to other countries located near the Gold Triangle, one of the places producing the largest amount of drugs in the world [9, 10]. In addition, Vietnam opened its doors to the outside world in 1988, resulting in an increasing gap between the rich and the poor, which warrants investigations in relation to socio-demographic factors and HIV infection risk. Several studies conducted in Vietnam at different times indicated that HIV infection has been spreading rapidly among drug users who are younger than before [5, 11, 12], which also highlights the urgent need for prevention activities in young IDUs. This study was conducted to facilitate the development of such targeted HIV prevention activities aiming at reducing HIV transmission within and from IDUs based on harm-reduction strategies. We evaluated the association of socio-demographic factors as well as their injection and sexual behaviors with HIV seroprevalence.

The prevalence of the HIV infection was 80 (32%) among the 248 IDUs aged 29 years old or less. The mean age of IDUs was 21.3 (standard deviation [SD]: 3.1, range: 14–29) years. The mean ages of HIV positive and negative IDUs were 21.1 and 21.3, respectively (P = 0.56, Student t-test). The proportion of the IDUs aged 17 years or younger, 18 to 20 years, 21 to 24 years and 25 to 29 years was 11.3%, 33.5%, 38.3%, and 16.9%, respectively. Most of the subjects (98.8%) were living with their relatives or family at the time of the survey. A high school or higher educational level was associated with lower prevalence of HIV (age-adjusted odd ratio (OR): 0.69, P = 0.034).

Among 80 HIV seropositive IDUs, 5.0% (n = 4) and 22.5% (n = 18) had shared needles or syringes more than half the time, or at least sometimes, respectively in the previous month of the survey. Two out of four IDUs (50.0%) who had shared needles more than half times had never used condoms with their wife or girlfriend. Ten out of 18 IDUs (55.6%) who had sometimes shared needles had never used condoms with their wife or girlfriend. Similar, but less pronounced trend was observed among HIV negative IDUs (33.3% and 45.5%, respectively).

The major findings of the present study are that the prevalence of HIV among a relatively young IDU sample enrolled in the hotspot communes in Long An, Vietnam is 32%, and that 18–20 years of age, low educational level, sharing injection equipment or injection drug use in the other cities were independently associated with HIV serostatus [15]. More than 1 out of 4 HIV infected IDUs were found to have shared needles in the previous month of the survey. About half of the IDUs who had shared needles never used condoms at their sexual contacts with primary partners regardless of the HIV serostatus. These results first suggest that current measures have not been sufficient to reduce risk behaviors in Vietnam, and that more efforts to reduce transmission risks of HIV infected IDUs would be needed.

Males aged 18 to 20 years old had a significantly higher HIV seroprevalence in the IDUs, and the association was independent of other factors. The result may be consistent with the previous studies conducted among IDUs and FSWs in Vietnam [1, 16], although the phenomenon may have been caused by the dropout due to dying or severe AIDS, which is less frequent among the younger IDUs or among those who started drug use more recently. Younger age is generally related to a lower economic status [10, 17, 18], which might have predisposed young IDUs to risky behaviors such as unsafe sex or sharing the injecting equipment, although age and these risk behaviors were not significantly associated in the present analysis. Because we sampled IDUs in the hotspot communes using the snowball method, they may not be representative of the whole IDU population in the province. Their socio-economic characteristics as well as the injection and sexual behaviors might have been similar reducing inter-individual variability in the variables. Although those aged 18 to 20 years seemed to be associated with higher HIV prevalence in the present sample, generalizability of the finding would be limited. Further studies are needed for better understanding of the risks associated with IDUs' age on HIV infection.

The duration of injection drug use or the age when beginning injection drugs was not associated with HIV serostatus in the present study, although it would reflect cumulative injection risk for HIV infection [4, 19, 20]. On the contrary, those with longer than 1 year but not exceeding 3 years use of injection drugs had a higher prevalence of HIV compared to those with less than 1 year of use. Although the failure of serologic assays during the window period in individuals shortly after infection might be associated with the lower seroprevalence in the reference group [21], it remains unclear why the IDUs' use of injection drugs for 3 years or more was not associated with increased prevalence. It could be speculated that the HIV-infected IDUs with a relatively longer history of drug injection might not be included in the present sample because their general health conditions were poor due to progression of the HIV infection [22]. Again, the present sample are not representative of the whole IDU population, so further studies using other sampling methods or with prospective design are needed to analyze the relation between the duration of injection drug use and HIV.

The adoption of injection reportedly occurred within a year on average [23], and a short transition period was reported to be an HIV risk [24]. We also found that the mean ages of IDUs when they started using drugs were only slightly lower than when they became injectors (19.0 vs. 19.4 years old, respectively), and most of the IDUs adopted the injection habit within a year (73.0%) or one to two years (17.3%). But we did not find any association between the duration of the transition period and HIV seroprevalence (data not shown).

The sexual behaviors of the IDUs reported at the time of the survey were not associated with their HIV serostatus. And, although not statistically significant, the association of FSWs and HIV infection seems rather contradictory [16]. Because the population of the present study does not represent the variability in the studied variables which would have existed if the whole IDU population had been sampled, no firm speculation based on the statistical testing could be made. Nevertheless, it may be possible that the IDUs who did not have sexual contacts with FSWs were of a lower economic status that also predisposed them to a much riskier situation [25, 26], or that HIV infection might have been the cause, rather than the effect of, not having contacts with FSWs [26, 27]. From another perspective, more than one-third of the IDUs responded that they had had multiple sex partners including FSWs, and that condoms had not been regularly used irrespective of their HIV serostatus. These cross-sectional results indicated that the heterosexual intercourse of the young IDUs in Vietnam would not be so much a source of their HIV infection [28] as a transmission risk, or a cause of spread to other populations [5, 9, 25, 29, 30]. They could well have served as a bridge in the transmission of HIV to other populations such as FSWs, clients of FSWs, wives of clients, children, and to the general population [11, 31]. Actually, these modes of transmission have been frequently observed in countries that experienced the transition from a concentrated to a generalized epidemic [32]. Although Vietnam is considered as a concentrated epidemic country [2], the fact that 32% of IDUs were found to be infected with HIV emphasized the importance of the present study which described and evaluated socio-demographic characteristics of IDUs, as well as the prevailing hazardous injection and sexual behaviors. HIV prevention efforts targeting IDUs must not underestimate the role of sexual transmission in the spread of infection among and from IDUs [10, 33]. More specifically in order to reduce sexual risks among IDUs, continuous efforts should be made to increase awareness not only of IDUs but also of others including HIV/AIDS staff or health care workers about the fact that IDUs are at high risk of HIV infection and transmission by unsafe sex as well as by sharing needles. Emphasis should be placed on the fact that many IDUs are sexually active and their primary sexual partners are at high infection risk. All information, education, and communication activities and behavior change interventions should include condom promotion component, and condom distribution/promotion activities can also be integrated to exchange/provision campaign of clean needles and syringes. The present results should be used to enhance or modify the development of such measures as to monitor risk behaviors in hidden populations and to improve preventive strategies to reduce transmission risk as a public health priority not only in Vietnam but in other countries as well.

Having used injection drugs in the other cities was associated with HIV seropositivity in the age-adjusted model. Among those who had used injection drugs in other cities, 91.3% migrated to Ho Chi Minh City, where the prevalence of IDU is the highest in Vietnam (73.6%) according to the report from the AIDS Division, Ministry of Health, Vietnam. It could be that those mobile IDUs had spread HIV infection from city to city. Epidemiologically, migrants have been known to be vulnerable to HIV risk [24, 34]. Riskier sexual behaviors were reported in traveling individuals with HIV [35]. Migration is often related to IDUs socioeconomic status (SES), and economic distress may have affected the IDUs who gave an affirmative answer to this question. Such conditions usually accompany a situation with limited access to appropriate information on HIV. Moreover, mobile IDUs may have visited shooting galleries where transmission risk of HIV would be high [36]. Less availability of social support was also reported in migrant IDUs, and was presumably associated with their risk-taking behaviors [37]. At the same time, there may be sexual or addiction-related motives that have driven them to cities where a certain social network exists despite their knowledge of the risks involved. It is also possible that HIV-infected IDUs tended to move to other cities to use injection drugs [10].

Further investigations are warranted with more detailed assessment of IDUs' geographic movement in relation to their sexual and injection behaviors so as to disentangle why this factor was related to IDUs' own HIV infection risk. In-depth qualitative studies on FSWs are also urgently needed since they often use injection drugs, are highly mobile, and are more vulnerable to HIV due to the lack of power or supportive environment, or peer pressure in a new area. Better understanding of these issues would help us to speculate or model how injection and sexual risk among IDUs may contribute to the larger epidemic not only within Vietnam but in the region located near Gold Triangle as a whole.

As with several other studies of IDUs[9, 11, 12], the limitations of the present study should be kept in mind. First, the present results were based on self-reports that might have been affected by ideas about social desirability or denial of recent risk behaviors. About one-third of IDUs (n = 80), all of whom identified themselves as never married, did not answer to the questions dealing with their sexual behavior. Although we obtained similar results from sensitivity analyses conducted as if these people had had either no or five or more sexual partners, caution is needed due to possible misclassification of the variable. In addition, we did not include any inquiries related to concurrency in partnership or homosexuality because we have paid less attention to the latter issue in Vietnam [38]. It is imaginable that disclosure of this issue may also be limited, and thus we have probably been underestimating the actual situation. Further investigations with an appropriate assessment of these issues are needed, possibly using some device to guarantee complete privacy. In terms of drug use-related inquiries, individual and contextual level factors related to injection initiation, chronological change in the level or pattern of drug use together with that of sexual activities, and characteristics of the drug use network should be assessed in future studies from both epidemiological and preventive points of view [39]. The number of needles exchanged in the area could be used as a surrogate measure of needle sharing. Since the information would make respondents aware that they should not share injection equipment or have sex without condoms, they may have tended to give a socially desirable response. Although this has serious implications when inferring causal relationships among them, the transmission risks evaluated in the present study underscore the urgent need for intervention as a public health priority.

Second, we did not obtain detailed information on the participant SES, nor did we inquire as to the reason why the IDUs had gone to other cities and had used injection drugs there. As mentioned in the earlier discussion of this issue, SES, both at the individual, family or community level, would have had a significant impact on the behavior risks, and future study must obtain a valid measure of SES in order to contribute to the development of effectively targeted prevention activities.

In future studies, not just general knowledge about HIV/AIDS of the IDUs but what has been causing barriers for behavior modification should be investigated. Health beliefs of IDUs should also be evaluated. Other psychiatric disorders including depression, post-traumatic disorders, and childhood abuse should be associated with their risk behaviors. In addition, other quantifiable assessments of drug use such as blood or urine test may well be combined.

Finally, it is usually not possible to determine the chronology between the associated factors and the actual HIV infection. Subjects who knew they were HIV seropositive might have changed to safe behaviors. Hence, the results of this study should be interpreted with caution and with respect for these limitations. Ideally, prospective observation or interventional studies should also be conducted.

In summary, being 18 to 20 years old, low educational level, sharing injection equipment or injection drug use in the other cities were associated with HIV seroprevalence among the studied IDUs in the hotspot communes in Long An, Vietnam. Prevailing risky sexual behavior of this extremely marginalized population highlights the need to reduce their high transmission risks as a public health priority. These findings also indicate the importance of addressing these issues including behavior education, supplying clean needles and syringes, condom distribution, and encouragement of HIV testing [7, 40, 41] as an efficient way to reach out to these hidden populations.