WEDNESDAY, July 30 (HealthDay News) -- The odds of HIV infection increase fourfold for male injection drug users who were deported to Tijuana from the United States compared to non-deportees in the Mexican border city, a new study reports.

The findings, expected to be presented Aug. 5 at the International AIDS Conference in Mexico City, suggest further investigation is necessary into the risk factors of displacement and the need for programs that offer support to displaced persons on either side of the U.S./Mexico border.

The University of California, San Diego, School of Medicine study was also expected to be published in the July 30 issue of Public Library of Science (PLoS) One.

Tijuana, the largest city on the U.S./Mexico border, is on a major route for both migrants headed to the United States and drug trafficking. The largest number of drug users per capita in Mexico live here and an estimated 5,000 female sex workers can be found in the city's busy zona roja (red light zone), the researchers said. All these factors contribute to a growing epidemic of HIV and other sexually transmitted infections in Tijuana.

The study compared HIV infection rates among 1,056 injection drug users (IDUs) in Tijuana, 86 percent of whom were male, and assessed potential risk factors that might increase the risk of HIV. While members of each gender had lived in Tijuana for similar periods of time, deportation was the most commonly cited reason for coming to the city among males (57 percent versus 30 percent among females). A greater proportion of men also reporting being homeless (15 percent versus 5 percent) and injecting drugs outside the home (43 percent versus 13 percent).

"Deportation was significantly associated with HIV infection in males," Steffanie A. Strathdee, chief of the division of international health and cross-cultural medicine at UC San Diego's School of Medicine, said in news release issued by the university. "In addition, the prevalence of HIV infection and potential risk factors differed by gender. But a finding we didn't anticipate is that living in Tijuana for longer periods was associated with lower HIV prevalence in men, which is the opposite of what we found in women. Among women, longer-term residents in Tijuana actually had a higher risk of HIV infection."

While the researchers admit such causal implications are unclear, their paper suggests deportation might be indicative of higher risk-taking. This may suggest that mobility rather than deportation itself creates unstable social conditions leading a person to pursue risky behaviors that lead to HIV acquisition, Strathdee said.

"With disintegrating family support networks, sudden changes in a person's cultural environment, homelessness and poverty, we're more apt to see risk behaviors such as unprotected sex with sex workers, other men or sharing injection needles among male migrants," Dr. Remedios Lozada, the HIV/STD coordinator of Baja California and director of the project's field activities in Tijuana, said in the university's news release. "However, an alternate explanation could be that deportation from the United States leads to social upheaval, loss of social ties and income factors which lead to engaging in high-risk behaviors."

The researchers call for further studies to determine whether specific interventions by U.S. or Mexico law enforcement could lower the risk of HIV transmission. They cited a Mexican government program being implemented in Tijuana that promotes HIV prevention and drug rehabilitation and provides temporary housing, food, clothing and medical attention to Mexican nationals who have been recently deported from the United States.

More information

The U.S. National Library of Medicine has more about HIV/AIDS.