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Should cut HIV deaths by 40%
Sometime this spring, Botswana will probably become the first African nation to roll out a nationwide program of isoniazid (INH) prophylaxis for HIV-infected patients. Because TB accounts for about 40% of HIV-related deaths in Botswana, the program promises substantial benefits for those who are HIV-infected, says Tom Kenyon, MD, MPH, director of the BOTUSA project, a collaboration between the United States and Botswana that is part of the Global AIDS Program of the Centers for Disease Control and Prevention.
A pilot project to test the intervention was started last August with 300 patients living in a mix of urban and rural areas. That pilot has demonstrated what researchers had hoped to find: namely, that the country’s corps of public health nurses, working independently, can screen out cases of active TB without the help of physicians or the use of chest X-rays.
If the intervention is to succeed on a broad scale, that’s critical, Kenyon explains. Though rich in health infrastructure, Botswana is short on physicians, and chest X-rays are prohibitively expensive, making their widespread use impractical. The pilot project uses chest X-rays only as a way to test the accuracy of the nurses’ assessments, he adds. "We’re finding that only about 1% of patients who are asymptomatic [by nurses’ findings] are found to have radiographic evidence of TB," he says.
Even when patients do have symptoms of TB disease, nurses are capable of managing the situation on their own, notes Kenyon. They examine a smear, and if it’s positive for acid-fast bacilli, they prescribe and administer anti-TB therapy, he says.
Candidates for the INH intervention include HIV-positive women recruited from mother-to-child HIV prevention programs and others from HIV counseling-and-testing sites. Compliance has been good so far, with about 80% of participants in the pilot project coming back each month to renew their supply of INH.
Health care workers are also reported to be enthusiastic. They give short-course antiretroviral therapy to pregnant mothers to protect their babies against HIV during labor and delivery. "Anecdotally, we hear that they like having something to offer the moms as well as the babies," says Kenyon. By preventing TB in mothers, of course, the INH intervention is also providing the added bonus of protecting infants against contracting TB from their mothers.
Still, the six-month regimen has its limitations. Among adults with HIV, the regimen confers about only 60% protection against TB, with benefits lasting about two to three years, Kenyon says. That’s why the plan is to begin testing lifelong INH prophylaxis eventually, he adds. "It’s pretty well accepted that we need to look at longer INH regimens," he says. "The reason we started with six months is because we wanted to at least get the intervention out there, and then look at questions related to duration."
Lifelong prophylaxis, often recommended in settings where the background of TB is so high that people are continually at risk for acquiring new infections, will be studied for two to three years, he adds — time enough to weigh potential problems and benefits.
No plans are being made, however, for testing short-course TB prophylaxis consisting of rifampin and pyrazinamide. "Rifampin is just too important to TB treatment here," says Kenyon. "There’s a fear of developing resistance."
A health post in virtually every village’
Among African nations, Botswana has an exceptionally strong public health infrastructure, marked by vigorous government commitment. The system is highly decentralized, resulting in
a situation where "everyone does everything," Kenyon notes. There are over 500 health posts for the country’s thinly spread population of 1.5 million people, "so there’s a health post in virtually every village," he says.
The country began using directly observed therapy for TB in 1986, before the practice even had a name, Kenyon notes. As a result, there is virtually no drug resistance in Botswana. On the other hand, the HIV epidemic has pushed the nation’s TB case rate to one of the highest on earth — 547/100,000 by 1999 estimates.
As elsewhere in the developing world, there is excited talk afoot these days of providing antiretroviral therapy at drastically reduced prices to AIDS victims, says Kenyon. (Recently, the Centers for Disease Control and Prevention surveyed the country to see what upgrades would need to be made to laboratories.) In the meantime, INH prophylaxis promises to be both cheap and sustainable and should give substantial hope to those waiting for something better.