Tuberculosis, one of the world's deadliest diseases, has long been forgotten by most Americans, but it is re-emerging in a new, virulent form around the world. U.S. health officials now worry that especially dangerous strains of the airborne pathogen have surfaced in Mexico, thanks to a dysfunctional health care system in the country's poorest regions. And they could spread to the United States.
Here's one scenario that keeps health officials on edge: A Mexican contracts the disease from a family member, or even a poorly run hospital, and then comes to the United States seeking work. There, living in crowded, cramped conditions without adequate ventilation, he passes it to several other migrants. But instead of promptly seeking medical assistance, the workers shun health care out of fear that they won't be treated or risk being deported. As a result, the disease festers and spreads.
Dr. Eugene McCray, the chief of the international tuberculosis elimination program at the U.S. Centers for Disease Control and Prevention, considers any legal barriers to care "abysmal, because people are in the community and they are going to transmit disease and it is going to affect Americans. It is very short-sighted." He said the best way to halt the disease isn't border protection, but increased collaboration and support to strengthen Mexico's health system. "For enlightened self-interest, we need to be concerned about tuberculosis," he said. "It has been totally ignored for many, many years."
Tuberculosis is a disease of poverty, exacerbated through crowded, dank living conditions and inadequate medical care. When the disease is not treated promptly and aggressively, it can easily pass between people living in close quarters, such as prisoners, refugees, migrant workers and their family members. Over the last decade, poor treatment has contributed to the growth of multidrug resistant (MDR) and extensively drug resistant (XDR) strains of TB, which are more deadly and far more stubborn than older strains.
"Unless the fundamental causes of MDR TB and XDR TB are addressed in the United States and internationally, the United States is likely to experience a growing number of cases ... that will be difficult, if not impossible, to treat or prevent," according to a 2009 report from the CDC.
The story of Marcela Gomez Vasquez and her family illustrates what can happen when proper treatment procedures are not followed. She lives with her six children in a mountain village of Chiapas, Mexico's southernmost state. The 44-year-old, a member of the indigenous Tzotzil community who speaks only cursory Spanish, contracted TB several years ago. She was given medicine and directions on taking it, but none of the regular supervision the World Health Organization (WHO) deems necessary for effective treatment. Even worse, her children never received prophylactic medication or screening. Two of them, Jose, 10, and Fidencio, 14, developed what appeared to be tubercular growths on their faces and necks.
The family lives in a small yellow concrete building, topped with a corrugated roof and situated on a patch of dirt atop a hill. These claustrophobic, dusty conditions, exacerbated by chronic malnutrition among many indigenous children, are ideal for transmitting the TB bacteria.
"I felt very bad. Sometimes children do not get better. If you do not know how to take care of the children they die," said Gomez. "I know how to take care of them which is why I kept bringing them to the clinic." The children had surgery to remove the growths and are now okay.
All told, according to the WHO, TB infected an estimated 9.4 million people in 2008 and killed 1.8 million of them. Of particular concern, however, are the 150,000 who died that year of MDR and XDR strains of the disease.
In global terms, Mexico isn't the chief concern. Nearly two-thirds of all new multidrug-resistant tuberculosis cases are concentrated in Russia, China and India, according to an estimate by Dr. Salmaan Keshavjee of Harvard Medical School. TB experts are particularly concerned about China, where reliable infection data is hard to get. Another major breeding ground for virulent strains of TB is the former Soviet Union, particularly its prisons, where patients are jammed together in dank surroundings and receive poor medical care. Some poor regions there have the highest proportion of TB ever documented, with more than a quarter of new cases being drug-resistant.
Still, there were more than 21,000 new cases of TB in Mexico in 2007, and epidemiologist Dr. Hector Javier Sanchez-Perez estimates that in Chiapas, Mexico's poorest and most politically marginalized state, 14 percent of all TB cases are MDR TB -- nearly three times higher than the global proportion.
Mexican government statistics put the MDR TB rate in Chiapas at closer to 4 percent, but government health officials acknowledge they do not have comprehensive data, and do not discount the higher estimate. Sanchez-Perez contends that the federal government keeps the official rate of MDR TB low "because it is an indicator of the low level of human development. It's embarrassing."
The presence of the drug-resistant forms of the disease, in particular, is a sign that a health system is functioning badly. Patients on TB medication must take the entire cycle, which lasts six months. Because of the dangers of the disease developing into a tough, drug-resistant strain, patients are supposed to be closely monitored by health authorities to make sure they're following the drug regime.
But such labor-intensive treatment can be difficult in developing countries with limited resources. The primary reasons for the disease's spread in the last decade are the increase in poverty and the HIV/AIDS epidemic, which compromises the immune system and thus makes people more susceptible to the bug.
Mexico has made gains in public health at a national level, but poorer states like Chiapas still lag far behind, plagued by poverty, malnutrition, poorly trained doctors, insufficient labs and poor infection control in hospitals and prisons. "We know that a lot of infections are probably being transmitted to other patients and health care workers," Dr. McCray said.
"The problem with TB is that it is characterized as usually affecting indigenous, poor people, so we continue to marginalize it, and therefore its victims do not have a voice. That is the big problem," said Dr. Alied Bencomo, the new chief TB official in the region. "Anyone can get it, like me, not just the poor. That is the message we need to get out there."