Steffanie Strathdee, public health researcher

A Canadian works with drug users and sex workers along the U.S.-Mexico border to fight epidemics of HIV and tuberculosis. Interview by Jennifer Welsh

May 25, 2010

Photo courtesy of Steffanie Strathdee

Steffanie Strathdee was a microbiology undergraduate at the University of Toronto when the human immunodeficiency virus [HIV] epidemic struck. "One day my professor was in class and the next week he wasn't. He had died of AIDS," Strathdee recalls. More deaths followed, including Strathdee's best friend and her Ph.D. supervisor. Influenced by these losses, she dedicated her life to studying how HIV spreads.

Strathdee went to work addressing the risk factors and rates of HIV infection in British Columbia, working on the Vanguard Project and other programs. Inspired by the book The Corner by David Simon, Strathdee moved to Johns Hopkins University to study the spread of HIV and hepatitis C among injection drug users in Baltimore.

Now she has followed the disease southward, combating epidemics in the marginalized populations of the Tijuana and San Diego border region. She is especially interested in how economic and sociopolitical influences help or hurt that spread.

Strathdee is chief of the Division of Global Public Health at the University of California, San Diego School of Medicine. She works directly with sex workers, addicts, and others prone to sexually transmitted diseases near the U.S.-Mexico border. What she found has troubled her.

Strathdee reviewed her research at the 2010 meeting of the American Association for the Advancement of Science in San Diego this February. She sat down with SciCom's Jennifer Welsh to discuss what is fueling this health conflagration—and what can be done to avert it.

How did you get into this field?

I was shocked to see that there was literally no research done on both sides of the border on the risks of HIV and sexually transmitted infections. We began a series of pilot studies and found very high risks for HIV and sexually transmitted infections, and also TB [tuberculosis]. I could see that the conditions in the environment were ripe for an epidemic. I was very concerned.

What specific problems make this epidemic so likely?

Borders are unique in a global context, providing places where people tend to congregate. In particular, with respect to this border, a number of features make it very high risk for infectious disease transmission.

The volume of cross-border traffic, especially in San Diego and Tijuana, is extremely large. It's actually the busiest land border crossing in the world. It's also a region of extreme poverty. The median income differential between the U.S. and Mexico is larger than for any other two contiguous countries in the world. It sets up this incredible push-pull, where a lot of people from other countries and southern parts of Mexico see it as a real corridor to the U.S.

It's also a drug trafficking corridor. Both Tijuana and Cuidad Juarez [a similar border town near El Paso, Texas] are on major drug trafficking routes. About 95% of the heroin that enters the U.S. west of the Mississippi River comes from Mexico. About 70% of the cocaine that enters the U.S. is trafficked through Mexico, and about 95% of all methamphetamines. Some drugs don't make it to their destination, and they end up getting used along the way by people involved in the trade.

Finally, it's an area where sex work is quasi-legal.

"The U.S. should be investing in prevention and treatment of these infections in the border region, in Mexico. The border shouldn't stop where the line is drawn."

So you have zones of tolerance, or zona rojas as they are often called. In Tijuana, there's a red-light district where women can work legally as long as they have a permit. About 5000 women work with permits and about half of that number work without, so you find that it's a region with a lot of sexual tourism.

Add all of these different factors together, and they create a recipe for an epidemic.

What do you think can be done about it?

It's really the social environment that shapes those individuals' behaviors. I also believe that when you have such a poor country next to the richest country in the world, the U.S. should bear a larger amount of the financial responsibility. The TB epidemic in California, and largely in the U.S., is driven by a lot of the influences affecting Mexico. For example, 82% of the HIV and TB co-infected cases are of Hispanic origin, and the majority of those are Mexican born.

The U.S. should be investing in prevention and treatment of these infections in the border region, in Mexico. The border shouldn't stop where the line is drawn; we should reach out and help our neighbors. It's really one population, and I think there is a shared responsibility on behalf of both countries to take care of the people in this region.

What's the best way to combat these blood-borne diseases?

A real combination approach is needed. Syringe exchange is really important, to give people access to sterile syringes so they won't share. Then we need to make sure that the police don't interfere with that.

Drug treatment is an important component as well. Methadone maintenance and buprenorphine maintenance are very important, because the majority of injection drug users in this part of the world are addicted to heroin. As opiates, buprenorphine and methodone both block the opioid receptors, and so it's very efficient. Every dollar spent on methadone maintenance saves seven dollars in future healthcare costs.

In addition, you need HIV testing, counseling, referrals for primary care and antiretroviral therapy. If you treat people with HIV with anti-retrovirals, the amount of HIV in their bloodstream drops below a critical level and they are less infectious. There is good evidence that widespread access to anti-retrovirals lowers the risk of transmission in the population.

It's a multi-pronged approach, with an impact on multiple outcomes. It's not just HIV—poverty, unemployment and deportation are also drivers for many of these infections. That's where we should be changing policies that are promoting harm instead of help.

This sounds expensive. Who should pay for these programs?

Some of it is expensive, but a needle costs less than 10 cents, and that can save a life. If you ramp that up to several million needles a year, people are bringing in a dirty one to get a clean one, so you don't have to worry about syringe disposal off the streets.

Methadone maintenance is very cost effective, because you are preventing infection and minimizing the harm that addiction has on the community at the broader level. It might seem costly upfront, but you are saving huge amounts of money in healthcare costs and costs to society.

You said you've gotten a lot of pushback from the Mexican police. Are there other people who don't agree with you on the needle exchange programs?

In the United States there has been a lot more pushback on the needle exchange programs than in Mexico. The U.S. just lifted the ban against federal dollars supporting needle exchange programs, which was in effect between 1988 and 2009. If anything, the negative attitudes from the U.S. influenced the Mexicans.

What are the negative things that people say about needle exchange programs?

If you look around the U.S., the opposition has said that needle exchange promotes drug use, that needle exchange will attract drug users to the area, that it will make people want to start using drugs, that it will increase crime, that it will increase the numbers of discarded needles on the streets.

I've investigated each of those questions and there is no evidence supporting any of them. Yet the opposition remained. When you really probe people who oppose needle exchange programs, it's on a moral basis rather than a scientific basis. You can't really argue against moral opposition.

You've started a non-profit that helps these people. Could you tell me more about it?

The non-profit is called PrevenCasa ["prevention house"]. We provide services to the high-risk populations that we study, because many of them didn't have health care, didn't know where to turn and were in great need. We do HIV testing, condom promotion, and we've started syringe exchanges. There was only one syringe exchange in all of Mexico when I first came to the region, and then Tijuana started one. Now, through support of the federal and state governments in Mexico, there are six Mexican states that have syringe exchange programs. We're really proud to contribute to that.

I donated a van that I had been using for my research studies to our non-profit organization. They use it to recruit participants for our studies and to provide services in off hours. It's called the PreveMovihl—preve, which means to test, but also has the connotation for prevention, and then movihl, since VIH is HIV in Spanish. The prevemovihl has caught on as a model of HIV service delivery, and the Mexican federal and state governments decided to make a fleet of these vehicles.

They have dancing caricatures of condoms, loudspeakers on the roof, and a big TV screen on the back. It looks like an ice cream truck, in a way, going down the zona roja saying "condónes, jeringas"—you know, condoms, syringes—and people of all walks of life come, from grandmothers to taxi drivers to little, underage sex workers who are afraid of going to a clinic.

What are some of the more emotional or affecting things you've seen?

There was a young fellow whose nickname was tortas, which is sandwich, because he liked these big sandwiches. He found out he was HIV positive the same day he found out that needle sharing spreads HIV. He didn't even know that sharing needles would be a risk, and it was too late. He was already infected. That should never happen.

More recently, there was Mary Lou. She had these little kids with her one day. "Well this one is my daughter," and she pointed to a little girl, about five years old. "And this one is my granddaughter," and she pointed to a little girl of three years old. And I said, "Oh well, where's your daughter? Are you babysitting today?" And she started to cry, and she said, "Well my daughter died of complications of HIV and TB last year, and now, I'm looking after my daughter and my granddaughter."

She was addicted to both methamphetamine and heroin, trying to get clean and trying to feed these kids. So she turned to sex work to do that. She tried to go on methodone, which helps the heroin addiction, but it doesn't help the methamphetamine addiction. She's had chronic relapses.

It's those kinds of experiences that really drive me. My goal is to put myself out of a job. Hopefully I'll be an old lady someday in a rocking chair and I'll say, "I remember this disease!" But that day hasn't come yet.

Jennifer Welsh, a graduate student in the Science Communication Program at UC Santa Cruz, earned her bachelor's degree in biological sciences from the University of Notre Dame. Shee has worked as a science writing intern at the Stanford University Medical School, the Santa Cruz Sentinel, and the science site of

© 2010 Jennifer Welsh