Thailand has experienced a significant decrease in HIV infection over the past 2 decades, with the greatest reductions in prevalence observed among the most at-risk populations.1–3 Despite this notable prevention success in controlling a former HIV epidemic (due, in large part, to the adoption of a government-initiated nationwide education and prevention campaigns4,5), Thailand’s HIV epidemic is thought to be poised for resurgence. HIV/AIDS is the leading cause of death for adolescent girls and second most common cause of death for adolescent boys and young adult men (15–24 years).6 Between 2000 and 2004, new sexually transmitted infection (STI) cases reported among Thai students increased from 3% to 10%.6
Thailand is experiencing a cultural transition in sexual norms and practices, particularly among adolescents and young adults.7,8 An increase in the acceptance of premarital sex coupled with a decrease in condom use among youth and young adults9 has been identified as one of the threats to Thailand’s continued HIV prevention success.1 This creates an emerging susceptible population, which will require new prevention strategies if Thailand is to maintain its goal of reducing its HIV epidemic. Limited information on the state of STIs in rural areas of Thailand exists; therefore, the current analysis examines the STI prevalence and associated sex- and age-specific risk factors among a representative sample of youth in rural Thailand.
These data were collected in advance of a community-based clustered randomized study designed to investigate the impact of community-level strategies to reduce substance use and STI/HIV-related risk behaviors among adolescents and young adults. These baseline data, with a participation rate of more than 90%, were collected using a community clustered design with a multistage-nested sampling design and provided a representative sample of the rural population aged 14 to 29 years (N = 2055).
The current analysis was restricted to the 1218 (59.3%) observations at baseline among participants who had experienced sexual debut and then further restricted to 1192 (97.9%) participants for whom STI testing was completed. The distribution of sex-, alcohol-, and drug-related STI risk factors across age and by sex and the associations between prevalent STIs and various sex-, alcohol-, and drug-related risk factors were evaluated. Participants testing positive for at least 1 STI (i.e., HIV, gonorrhea, or chlamydia) at baseline were identified as having a prevalent STI. Prevalent STI was defined in this manner to improve statistical power and highlight risks and protective factors associated with the general burden of disease without focus on any one infection. Odds ratios (ORs) were obtained using generalized linear regression with general estimating equation methods (XTGEE, Stata 12.0) and robust standard error estimation to account for the correlation between individuals sampled from the same subdistrict.
The demographics of the sample are given in Table 1. At baseline, 10.0%, 1.9%, and 1.1% of the sample had prevalent chlamydia, gonorrhea, or HIV, respectively, with an overall HIV or STI prevalence of 12.4%. The prevalence of any STI/HIV by district among those reporting sexual debut ranged from 8.9% in Chiang Dao to 15.7% in San Kampaeng, variation that may be caused by distance from the city, presence of a university, or unmeasured differences including community and network factors. Sex-, drug-, and alcohol-related STI risk behaviors varied by age and sex. Compared with women, men had an earlier average age of sexual debut, were more likely to have multiple partners in the last 3 months, had lower proportions of protected sex, and had a greater number of lifetime sex partners. Although low for both sexes, women used condoms less often during sex with their regular partners than men. Having sex while drunk or high was more prevalent in men and older age groups. As age category increased, the percentage of protected anal and vaginal sex decreased. There was a statistically significant change in the type of partner across ages, likely owing to the increase in the proportion of adolescents with regular partners as age increased. Condom use with regular partners but not casual partners decreased with age.
Among 14 to 19 year olds, those with casual partners had statistically significantly higher odds of having an STI in the multiple logistic regression model (Table 2). This was true for those with both more frequent protected sex and less frequent protected sex with casual partners. This pattern of association was not present for older age groups. Although those who were married (9.6%) were moderately less likely to have an STI than those not married (13.5%, P = 0.07), the additional protection afforded by marriage compared with those that reported regular (but nonmarital relationships) was not statistically significant (OR, 0.740; 95% confidence interval [CI], 0.468–1.17; results not shown).
An interaction was observed between frequency of alcohol use and sex. For men, increased alcohol use was negatively associated with STIs at baseline, conferring 81% and 76% decrease in odds for those who used alcohol less than 1 time a week or greater than 1 time a week, respectively, compared with men who never used alcohol. In contrast, women had almost 4 times the odds of STIs when using alcohol less than 1 time a week compared with women who had never used alcohol (adjusted OR [aOR], 3.76; 95% CI, 1.30–10.9). Nondrinking women had a 90% decreased odds of STIs compared with nondrinking men (aOR, 0.098; 95% CI, 0.018–0.526; results not shown), all else being equal.
We report a number of sex differences in the alcohol, drug, and sexual risk behaviors for rural Thais between the ages of 14 and 29 years. The greater use of condoms in men compared with women regardless of the type of partner (casual or regular) may reflect the transition in young men from sex with commercial sex workers to regular and casual partners and the greater exposure and saliency of HIV-prevention messages, given the socially sanctioned earlier sexual debut and high-risk nature of the commercial partners of young men. Traditionally, male adolescents in urban settings are often taken to a brothel by older friends or relatives for their first sexual experience10; however, the literature also suggests a trend for young men in response to the HIV epidemic in Thailand away from commercial sex because of fears of acquiring HIV.7,11 Age also modified the effects of a number of risk factors, showing a trend toward diminishing risk at older ages, which coincides with the current literature suggesting that STIs and sexual attitudes and behavior vary by age.6,12–14
Sex differences in STI risk factors have been found in other studies.15 However, the current study found new evidence to suggest that alcohol use may increase the risk of prevalent STIs for women but protect men. The social norms of rural Thai sexual behavior may provide some insight into understanding the observed interaction between alcohol use and sex on STI risk. Although the sex gap in premarital sexual exploration16 is narrowing in Thailand, the impact of sex-based sexual norms may remain particularly salient for rural youth. Specifically, the increased sexual freedom for Thai women described by researchers in urban settings7 may not apply to women in rural Thailand. Compared with Thai youth in urban settings, extended and neighboring families have a greater purview and authority over the social behavior of youth in these tight-knit rural settings,17 creating a context in which traditional, sex-disparate norms can be directly or indirectly enforced.12,13 For rural youth, greater obligation to and dependence on family may further reinforce family control18 and traditional social structures. Alcohol has been thought to decrease inhibitions19; however, many researchers suggest alcohol exerts its effects, not through physiological pathways (i.e., disinhibition of the brain control centers that restrain sexual impulses) but through cognitive and social learning processes whereby alcohol is a cue for a set of socially sanctioned, less constrained behaviors.20,21 The observed interaction between sex and alcohol may be a reflection of physiologically or cognitively driven departure from sex-based social norms on sexual behavior, norms that are more constraining for women than for men. Furthermore, because young women have essentially been overlooked by public health campaigns, there may be a reduced ability for women to manage their risk properly.7
The current study was limited by the cross-sectional nature of the data, and the correlates described should not be construed as causal factors. However, the study is novel in its examination of STIs and their individual-level correlates in a representative sample of rural Thai adolescents. Our study suggests that interventions in the rural context should incorporate sex-specific education on the effects of alcohol on sexual behavior, with specific attention to addressing the needs and risks of young women. Energy should also be focused on the youngest adolescents who, this study suggests, may be at highest risk for STI and who have the least experience with drinking alcohol. Finally, interventions addressing the realities of sexual norms and the persistence of sex biases, particularly in rural settings, could encourage the incorporation of new health-related behavior within the context of existing value systems.
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