Adolescents migrating from Central America and Mexico to the United States are at risk for being trafficked into the sex industry in Mexico’s northern border cities.1 Research from other regions indicates that those entering the sex trade as adolescents, versus as adults, are more likely to experience sexual violence and human immunodeficiency virus (HIV) risk during initiation into the sex trade,2 and to become HIV infected.3 Apart from one study among injection drug-users,4 no research exists on the prevalence of minors in the sex industry in Latin America or their subsequent risk for violence and HIV infection.
Methods
Between March 2013 and January 2014, female sex workers 18 years and older were recruited from Tijuana and Ciudad Juarez, Mexico via time-location sampling (a method used to simulate random cluster sampling for studies of hard-to-reach populations5) involving random sampling of sex work venues based on venue mapping, with probability of selection proportional to venue size. Of 200 venues identified, 25 did not permit recruitment; venue type did not differ based on permission for recruitment. Of 1041 individuals screened, 614 were eligible and 603 participated (98.2% cooperation rate). Confidential computer-assisted surveys were completed to assess prevalence of adolescent (16–17 years) and early adolescent (< 16 years) entry to sex trade and associations of age at entry with violence to force commercial sex, high client volume (> 10 clients/day), and no condom use during the initial 30 days post-entry (two-sided tests, p < 0.05). Multivariable logistic regression analyses were adjusted for current age, education, city, and marital and migration status at entry (p < 0.05). Modeling for HIV infection (serologically assessed) based on age at sex trade entry (< 18 vs. 18+ years to conserve power given small numbers of HIV cases) was adjusted for current age, recent condom use, and lifetime injection drug use. Analyses were conducted using SAS 9.4. Participants provided written informed consent and received 20 USD and indicated HIV counseling and treatment referrals. Protocols were approved by the University of California, El Colegio de la Frontera Norte and Universidad Autonoma de Ciudad Juarez.
Results
Of 603 female sex workers (mean age 34.3 years; SD 10.4), 25.4% reported entering the sex trade before age 18 years; 11.8% reported entering under age 16 years. Compared with those entering sex work as adults, those entering the sex trade as adolescents were more likely to report experiencing violence to force commercial sex (< 16 years only; 19.7% among < 16 years, AOR 2.5, 95%CI, 1.2-5.2, vs. 8.7% among adults), high client volume (21.1% among <16 years, AOR 2.4, 95% CI, 1.2-5.0; 19.5% for 16 – 17 years, AOR 2.4, 1.3-4.6, vs. 9.6% among adults), and no use of condoms with clients (< 16 years only; 35.2% among <16 years, AOR 6.6, 95% CI, 3.3-13.2, vs. 8.0% among adults) during their first 30 days in the sex industry. Those reporting entering the sex trade as adolescents were more likely to be infected with HIV compared with those entering as adults (5.9% among < 18 years vs 1.6% for adults, AOR 3.1, 95% CI, 1.1-9.3).
Discussion
More than 1 in 4 female sex workers in these northern Mexican cities reported entering the sex trade as minors. Entering the sex trade as an adolescent vs. as an adult was associated with a three-fold greater risk for HIV infection. Increased HIV infection among those reporting adolescent sex trade may relate to elevated risks for violence to force participation in commercial sex, higher numbers of clients, and condom non-use during initiation to the sex industry. Efforts demonstrated to effectively protect adolescents vulnerable to sex trade entry and to assist adolescents in the sex industry are needed. Study limitations include potential recall bias in retrospective reporting, and such bias differing based on longer duration of sex work; to address this concern, adjusted models included both age at entry and current age. Although consistent with studies of sex workers in other regions,3 current findings may not generalize to other sex worker populations.
Table 1.
Sample characteristics and associations* with age at entry into commercial sex trade among female sex workers in Tijuana and Ciudad Juarez, Mexico (N=603)
| Total Sample (N = 603) |
Age at Entry | ||||
|---|---|---|---|---|---|
| <16 years (11.8%; n=71) |
16–17 years (13.6%; n=82) |
18+ years (74.6%; n=450) |
|||
| % (n) | % (n) | % (n) | % (n) | p-value† | |
| Current age | |||||
| Mean (SD) | 34.3 (10.4) | 32.4 (9.1) | 32.7 (10.9) | 34.9 (10.4) | 0.049 |
| Sex work duration (years) | |||||
| Mean (SD) | 11.7 (9.7) | 18.2 (9.3) | 16.1 (11.0) | 9.9 (8.8) | <.001 |
| Education | |||||
| Primary or less | 44.3 (267) | 59.2 (42) | 46.3 (38) | 41.6 (187) | 0.004 |
| At least some secondary | 39.1 (236) | 36.6 (26) | 30.5 (25) | 41.1 (185) | |
| Beyond secondary | 16.6 (100) | 4.2 (3) | 23.2 (19) | 17.3 (78) | |
| Migration at Entry | 7.7 (46) | 11.3 (8) | 3.7 (3) | 7.8 (35) | 0.211 |
| Marital status at Entry | |||||
| Married before entry | 40.1 (242) | 15.5 (11) | 29.3 (24) | 46.0 (207) | <.001 |
| Married at entry | 5.5 (33) | 18.3 (13) | 6.1 (5) | 3.3 (15) | |
| After entry/never married | 54.4 (328) | 66.2 (47) | 64.6 (53) | 50.7 (228) | |
| City of Interview | |||||
| Ciudad Juarez | 50.1 (302) | 45.1 (32) | 59.8 (49) | 49.1 (221) | 0.144 |
| Tijuana | 49.9 (301) | 54.9 (39) | 40.2 (33) | 50.9 (229) | |
| Inconsistent condom use with commercial partners, past 30 days |
33.3 (200) | 45.1 (32) | 45.1 (37) | 29.3 (131) | 0.002 |
| Lifetime injection drug use ever | 24.4 (147) | 52.1 (37) | 34.2 (28) | 18.2 (82) | <.001 |
Associations assessed via two-sided chi-square test and ANOVA. Analyses were conducted using SAS 9.4 (SAS Institute, Inc., Version 9.4, Cary, NC; SAS Institute Inc., 2013)
ANOVA for continuous variables and Chi-square for categorical variables
Table 2.
Adjusted associations* of age at entry into sex trade and violence and HIV risk during first month of sex trade and HIV infection among female sex workers in Tijuana and Ciudad Juarez, Mexico (N=603)
| During 1st month in sex trade | Current | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Violence to force commercial sex 10.8%; n = 65 |
High client volume 12.3%; n = 74 |
Never used condoms 11.8%; n = 71 |
HIV 2.7%; n = 16 |
|||||||||
| % (n) | AOR† (95% CI) | p-value¶ | % (n) | AOR† (95% CI) | p-value¶ | % (n) | AOR† (95% CI) | p-value¶ | % (n) | AOR‡ (95% CI) | p-value¶ | |
| Age at entry | ||||||||||||
| <16 years | 19.7 (14) | 2.5 (1.2 – 5.2) | 0.014 | 21.1 (15) | 2.4 (1.2 – 5.0) | 0.016 | 35.2 (25) | 6.6 (3.3 – 13.2) | <.001 | - | - | - |
| 16 – 17 years | 14.6 (12) | 2.0 (1.0 – 4.2) | 0.058 | 19.5 (16) | 2.4 (1.3 – 4.6) | 0.007 | 12.2 (10) | 1.8 (0.8 – 4.0) | 0.153 | - | - | - |
| <18 years | - | - | - | - | - | - | 5.9 (9) | 3.1 (1.1 – 9.3)§ | 0.037 | |||
| 18+ years # | 8.7 (39) | REF | 9.6 (43) | REF | 8.0 (36) | REF | 1.6 (7) | REF | ||||
Associations assessed via logistic regression. Analyses were conducted using SAS 9.4 (SAS Institute, Inc., Version 9.4, Cary, NC; SAS Institute Inc., 2013)
Models adjusted for current age, education, marital status at entry, city of interview, and migration at entry. Duration of sex work was not included as a covariate due to multicollinearity with age at entry and current age.
Model adjusted for current age, past 30 day condom use, lifetime injection drug use. Duration of sex work was not included as a covariate due to multicollinearity with age at entry and current age.
Type III test of fixed effects
Adjusted odds ratio presented is for < 18 years of age at entry vs. 18+ years based on the limited statistical power for analyses of HIV infection given the small number of HIV cases (n=16)
Reference group is 18+ years old at age of entry
Acknowledgments
Funding: The study was supported via funding from the National Institute on Drug Abuse (R01DA033194 to J. Silverman and R01DA028692 to K. Brouwer) and the UCSD Center for AIDS Research via NIAID (P30A136214, PI: D. Richmond). The funders took no part in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.
Footnotes
Authorship Contributions:
JGS led conception and design of the work and analysis, interpretation of data, drafting of the work including the final version, and is accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.
AS made substantial contributions to acquisition of data for the work, revised critically for important intellectual content, gave final approval of the version to be published, and agrees to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.
SMG made substantial contributions to conception of the work, drafting of the work, gave final approval of the version to be published, and agrees to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.
CMR contributed to interpretation of data, revising it critically for important intellectual content, give final approval of the version to be published, and agrees to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.
JR made substantial contributions to analysis of data, revised critically for important intellectual content, gave final approval of the version to be published, and agrees to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.
AR made substantial contributions to conception of the work, drafting of the work, gave final approval of the version to be published, and agrees to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.
KCB made substantial contributions to acquisition of data for the work, revised critically for important intellectual content, gave final approval of the version to be published, and agrees to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.
Other contributions: Leah Gordon, MPH, made critical contributions to the collection and analysis of data and revision of this manuscript. Additionally, she and Sabrina Boyce, MPH, made critical contributions to the revision of this manuscript. Both were compensated as employees of UCSD School of Medicine.
The authors state that they have no conflicts of interest or financial disclosures.
I, Jay Silverman, had full access to all the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis.
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