With tuberculosis the leading cause of death worldwide among people with AIDS, a leading charity has awarded $44.7 million to a consortium led by Johns Hopkins scientists that aims to find the best way to combat the twin epidemics in developing nations.
The Bill & Melinda Gates Foundation announced the grant yesterday at the XV International Conference on AIDS in Bangkok, Thailand. The money will pay for projects in South America and Africa, including one that will deliver anti-TB medications to thousands of coal miners across South Africa.
Scientists will dispense the drug isoniazid, which has been used for 50 years in Western nations - but rarely in the Third World - to keep people who have been exposed to TB from getting sick with the active disease.
"There has been a belief that giving preventive therapies is not effective for controlling the disease," said Dr. Richard Chaisson, a Hopkins professor of infectious diseases who is heading the effort. "I think there is very good evidence that's not correct."
As examples, he noted a program in which Hopkins researchers virtually eliminated the threat of tuberculosis among hundreds of Baltimore drug addicts who had been exposed to the disease. Such exposure is measured by a person's reaction in skin tests.
In another instance, researchers stopped an epidemic of TB in Alaska by treating everyone in a community with the medication, regardless of their exposure.
The Gates money goes to the Hopkins-led group Consortium to Respond Effectively to the AIDS-TB Epidemics. Joining Hopkins are scientists in London, South Africa and Brazil, and others with the World Health Organization and the U.S. Centers for Disease Control and Prevention.
People with acquired immune deficiency syndrome are particularly vulnerable to tuberculosis because of their weakened immune systems. When tuberculosis takes hold among people infected with the AIDS virus, it also threatens to break out among the broader population, experts say.
"Anyone concerned about HIV/AIDS must also be concerned about TB because the two diseases go hand in hand," Dr. Helene Gayle, an official with the Gates Foundation, said in a statement.
"I'm optimistic that researchers, policymakers and funders around the world will recognize the need to alleviate the tremendous burden of these linked epidemics."
Chaisson said the presence of each disease amplifies the other, particularly in developing nations where medications and primary health care are scarce.
The incidence of tuberculosis is increasing 3 percent per year, with about 9 million new cases expected this year, Chaisson said. "In 20 years, the rate will be twice what it is now, and it's very high," he said.
"TB has been a curable disease for 60 years," he said. "You would think if we had the cure for that long it should be gone, but it's not."
Hopkins will oversee the three projects covered by the grants - one in Brazil, two in Africa - but will carry out the work in Brazil only. The other projects will be directed by collaborating institutions.
In Rio de Janeiro, researchers plan to give isoniazid to more than 20,000 people who are infected with TB and the human immunodeficiency virus and have access to antiretroviral drugs that slow the progress of HIV infection. There, scientists will determine whether adding isoniazid to AIDS drugs will prevent tuberculosis and slow transmission of TB.
In South Africa, scientists plan to divide the nation's gold miners into two groups. In one group, public health workers will deliver isoniazid to all miners, whether or not they are infected with HIV. In the other, the drug will be given only to the HIV-infected workers.
Scientists hope to learn whether a mass assault on tuberculosis is better than a more targeted strategy where both diseases are rampant.
The mines have an estimated 70,000 employees.
"Gold miners have the highest rates of TB in the world, and they also have the highest rates of HIV," said Chaisson. About a third of gold miners are infected with HIV, and about 90 percent test positive on TB skin tests.
HIV infection is widespread because the miners, living miles from home, often consort with prostitutes infected with the virus. Tuberculosis spreads rapidly because the miners work in poorly ventilated shafts and sleep in crowded dormitories. Both environments promote TB, which is spread by coughing.
The third project will be in Zambia and South Africa, where scientists will determine whether they can reduce TB rates through education in the schools and the community at large. They also plan to test the benefits of providing isoniazid to all members of households where TB patients live.
Besides heading the Gates-funded project, Chaisson is director of the Johns Hopkins Center for Tuberculosis Research. From 1988 to 1998, he headed the Johns Hopkins AIDS service.
Earlier in the 1980s, Chaisson trained and was as an assistant professor at the University of California, San Francisco. During that time, AIDS was spreading rapidly through the gay community of San Francisco, which was among the first cities where the epidemic took hold.
With an endowment of $27 billion, the Seattle-based Gates Foundation has awarded considerable sums to programs targeting AIDS, malaria and other infectious diseases. The Johns Hopkins Bloomberg School of Public Health has received more than $100 million from the foundation, including $40 million last year for its program in population and reproductive health.