Congress is once again debating illegal immigration. A new bill in the House would create a guest worker program for undocumented immigrants but would require that they go home after six years. For most of the estimated 12 million illegal immigrants in the United States, home is Mexico. Migrants come north for jobs and a better life. But when they go home, they may bring something harmful with them. Doctors say migration is fueling the spread of the AIDS virus in Mexico. The World's Jori Lewis reports.
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Lewis: Mexico's overall HIV rate is quite low; it's roughly half the rate in the US. That low prevalence holds for Mexican migrants as well, but the numbers have started to change.

Lemp: "We've seen more HIV entering that population more recently."

Lewis: Epidemiologist George Lemp directs the University of California's AIDS research program. His group has been working with the Mexican government's AIDS agency to study HIV rates among migrants in California. He says there's growing evidence that some migrants are getting HIV in the US and are taking the virus back to Mexico.

Lemp: "In Mexico, there are specific villages and towns that are fairly small and remote where one wouldn't expect to find HIV infection where women are becoming infected with hiv. The only risk factor that's apparent is that their male sexual partner or husband had travelled to California or other places of the United States and brought HIV back."

Lewis: Lemp says it's clear how those men get infected.

Lemp: "There's a tremendous amount of high risk behavior occurring among migrants."

Lewis: Lemp says many migrants are young men with limited education who find themselves far from their traditional communities for the first time. Some start experimenting with unprotected sex and injection drugs. And the risky behavior occurs not just in migrant camps in San Diego or Fresno but also in those migrant way stations just south of the border.

Cities like Tijuana, the self-described gateway to Mexico. It's one of the busiest border crossings in the world and a major staging port for cocaine, heroin and meth distributors. Tijuana police and army officers patrol the streets with automatic weapons. Locals, migrants and tourists gather at nightclubs and bars pumping out norteno music. Hot pink and turquoise painted stores sell cheap tequila. And a bevy of equally colorful prostitutes work the streets.

Tijuana River canal

Borders are places where people, drugs and disease often mix and Tijuana is no different. Steffanie Strathdee is an epidemiologist at the University of California in San Diego who has studied HIV in Tijuana.

Strathdee: "We have a lot of mobility. We have a lot of people coming from southern parts of Mexico and South America in search of the American dream and unfortunately Tijuana is a place of a lot of broken dreams because they didn't make it on their way to the US or they got deported. And these kind of sad stories contribute to a lot of despair, hopelessness and sometimes addiction, sex work and unfortunately with it sometimes HIV and STDs."

Lewis: Strathdee is particularly concerned about people like Angel Hernandez. He's a deportee who lives in the Tijuana River Canal and has been injecting heroin and meth for nearly a decade. Hernandez is worried about himself.

Hernandez: "I could get AIDS because of sharing needles with people I really don't know."

Lewis: Hernandez recently took an HIV test and is waiting for his results. He knows that if he's positive, there's a good chance his wife is as well. She lives in Acapulco and at least once a year he makes the 2,000 mile journey home.

A popular drug user hangout

Dr. Remedios Lozada coordinates HIV programs for the Mexican state of Baja California. She says to protect the broader public from HIV, it's critical to work with high risk populations in Tijuana.

Lozada: "This is a vulnerable population and sometimes people think it's a small group--those using drugs. But really, as we've seen in other countries where they didn't address the problem immediately, it could spread. And so we have to be careful and we have to intervene."

A drug user wades through the Tijuana River canal

Lewis: And they are intervening. Dr. Lozada runs an organization called COMUSIDA that reaches out to those at high risk for HIV. In the Tijuana River Canal, where Angel Hernandez and many others live in the sewer outflows, COMUSIDA workers pass around a disposal box for old needles.

COMUSIDA bus

The users are eager trade in their needles for new ones. They run up to the van, through the dirty water of the canal. One man stops mid-fix of his Tijuana speedball of meth and heroin, to talk to a COMUSIDA worker whose forearms are covered with tattoos. His name is Cabrera and he's a former injection drug user who shared needles and contracted Hepatitis C. He's been clean for six years and now brings the gospel of harm reduction to his old running buddies.

Safe disposal box for dirty needles

Cabrera: "If there was a program like this when I was using drugs, I would have used it. And I think that now we're doing this, it will help a lot of people."

Lewis: Cabrera and the others pass out safe injection kits: new syringes, clean bits of cotton, bleach and purified water. Normally users make do with the brown water from the Tijuana River to shoot up. From here, the water passes under streets and highways. And then it crosses the border.

Tijuana River canal sewer outflow

Every day migrants cross the border, too, says Steffanie Strathdee at UC San Diego. She says HIV spreads along migration and drug trafficking routes--routes that stretch out of Mexico and into the US.

Strathdee: "When you have an epidemic like HIV in a border region it's a shared responsibility and it needs a shared response."

Lewis: Strathdee is collaborating on a study with Dr. Lozada in Tijuana. They are researching the local epidemic and teaching people how to protect themselves from HIV. Strathdee and Lozada hope that as people move from Tijuana north to their adopted American cities or South to their hometowns, they'll take a little prevention know-how with them.

For the World, I'm Jori Lewis, Tijuana, Mexico.