Crossing the Border

THE SAN YSIDRO border crossing is the world’s busiest, with roughly 50,000 vehicles and 25,000 pedestrians crossing from Mexico into the United States daily. While there has been much debate about illegal immigrants and terrorists, little has been said about a different, yet very real cross-border risk: infectious disease. A report released in June from the International Community Foundation (ICF) in San Diego highlights a problem that will not be stopped by walls and fences—the spread of diseases like tuberculosis, human immunodeficiency virus (HIV) and influenza between Tijuana and San Diego.

The ICF, a charity that helps underserved communities internationally— with 70 percent of its grants benefiting causes along the Baja peninsula—is headed by Richard Kly, who coauthored a report called “Shared Destiny” with Robert L. Bach, a faculty member at the Center for Homeland Defense and Security, Naval Postgraduate School in Monterey. They write that the need for expansion of cross-border health services is more urgent now than ever before.

Border cities usually have higher rates of infectious disease than non-border cities, says Stephen Waterman, senior medical epidemiologist for the Centers for Disease Control’s Quarantine Station in San Diego. Rapid growth in Tijuana—and the subsequent proliferation of squatter communities—breeds disease, says Kly, who believes a crisis is developing in the area of tuberculosis and HIV. Last year, Tijuana reported about 600 TB cases; San Diego, 305.

Although Kathleen Moser, director of the Tuberculosis and Refugee Health Program for the county, finds rates have been fairly level over the past few years, she agrees they certainly aren’t low. Tuberculosis has been a curable disease for more than 50 years, which means the number of reported cases should be zero by now, she says. “But it is the second-largest infectious-disease killer of adults throughout the world—about 2 million deaths a year.” Only AIDS kills more people.

Nationally, the TB rate among residents of border counties is 10.4 per 100,000 people; for those in non-border counties, it’s about 5.1. In Tijuana, Moser says, officials generally acknowledge underreporting and believe the incidence is probably between 50 and 100. Tuberculosis is spread person-to-person through the air and, if inhaled, will often infect, although only about 10 percent of those infected will get sick. It’s estimated that one-third of the world’s population is infected with the disease, says Moser. “That’s 2 billion people, waiting to infect others,” she says. To cure TB, medication must be taken for six months to a year; if it is one of the newer, drug-resistant strains, treatment can take up to two years.

In an effort to track those with the disease and make sure it is treated, the Centers for Disease Control (CDC) and the state fund a program called Cure TB, headed by Moser. Cure TB just restarted Project Acceso, a campaign on Spanish-language radio and television to alert people to the symptoms of TB. A toll-free number is provided to help those who suspect they may have the disease get diagnosed and treated.

THE INCIDENCE of another dangerous disease, HIV, is also high, in both San Diego County and Tijuana. Kly points to a 2002 study of blood samples from 374 gay and bisexual Hispanic men 18-29 years old—125 from San Diego and the rest from Tijuana. Thirty-five percent of the San Diego men and 19 percent of those from Tijuana were infected with HIV and had never been tested. Kly says that 1.1 percent of pregnant women in Tijuana are currently being diagnosed with HIV.

About one in 125 residents of Tijuana between 15 and 45 are HIV-positive, says Steffanie Strathdee, the Harold Simon Professor of International Health at UCSD and an expert on HIV and AIDs. It’s about the same on the San Diego side of the border, she says. Strathdee, an epidemiologist, was one of the country’s first HIV researchers and has been studying the disease since the 1980s. She worries HIV could quickly become epidemic in certain populations.

“You take a city the size of Tijuana or San Diego and have a lot of people not knowing they are infected, sharing needles and having multiple sex partners, and it can spread very quickly. Over and over again I have seen the epidemic escalate almost overnight,” says Strathdee. “We have seen, in populations like injection-drug users, that once it hits between 5 and 10 percent, it can go to 60, 80 or 90 percent in a single year.”

In the 1990s, she says, data indicates that HIV prevalence among sex workers and drug users in Tijuana was less than 2 percent. Now it’s up to about 8 percent in sex workers and 6 percent for drug users. Today, the prevalence of HIV in gay men in Tijuana and San Diego is estimated to be about the same, around 15 percent.

“It’s not just the numbers you have to look at, it’s the trend, and it’s [moving] in a worrisome direction,” says Strathdee. “Tijuana’s formerly low prevalence of HIV has quickly caught up to San Diego’s rate. It’s a binational epidemic, and diagnosis and treatment needs to be a shared responsibility.”

Some joint efforts have already begun. In mid-July, UCSD scientists who study HIV met with San Diego Mayor Jerry Sanders and Baja California Governor Eugenio Elurduy Walther to discuss prevention priorities. UCSD has donated a mobile clinic—Preve Movihl—to take testing and prevention education to the people, rather than waiting for them to come into a clinic. Fronteras Unidas Pro Salud in Tijuana, the result of a partnership between Planned Parenthood of San Diego & Riverside Counties and Mexfam (Mexico’s family planning organization), provides low-cost reproductive healthcare and education to families throughout Baja.

AS FOR FEARS of a flu pandemic developing in Mexico and then spreading north, the CDC’s Waterman says that’s not a likely scenario. Especially if the current avian strain mutates and becomes a human epidemic, Waterman says, “it’s much more likely to be introduced on a plane flight from Asia than it is from a commuter in Mexico.”

But “Shared Destiny” coauthors Kly and Bach found considerably more reason to be concerned. The authors write, “Pandemic flu, which could cause nearly 40 percent of the region’s workforce to remain at home and kill hundreds of thousands, represents perhaps the most plausible, catastrophic cross-border risk.”

Kly says the San Diego–Baja California region is particularly vulnerable to the spread of avian flu because of substandard living conditions, especially in Tijuana, where humans and chickens live in close proximity. Mexican communities on both sides of the border raise chickens for consumption, and many households own caged birds and roosters for cockfighting, the authors say.

The CDC now monitors influenza at the border in San Ysidro, and the United States is working with Mexico and Canada to plan a response directed at pandemics and influenza through the Security and Prosperity Partnership of North America. In the event a dangerous influenza strain appears in Mexico before the United States, Waterman says, “Closing the border isn’t a realistic option, but we do need a plan to minimize movement of the virus across borders, and to coordinate our efforts to track disease and use quarantine policies.”

Controlling infectious disease and its potential spread across the border requires a binational effort, experts say. Healthcare in the San Diego border region is “in such disarray, and health conditions so dismal for so many, that even a willingness to spend more money on health would be counterproductive,” write Kly and Bach in their report—unless community leaders on both sides of the border start working together.

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