As many as one out of three people in the world are infected with the bacteria that causes tuberculosis, public health experts estimate. That could lead to a global plague were it not for the fact that only one out of 10 infected people actually develops the disease.
Still, TB is a major global health problem, particularly in developing countries. It sickens 8 million additional people each year, of which 2 million will die. So if scientists could find out what is going on in the bodies of the other nine people, they might be able to save millions of lives and avoid a great deal of suffering.
Part of the problem involves environmental factors such as poverty, stress, malnutrition, and companion diseases like AIDS. But researchers have known for a long time that variations in genes also play a significant role in TB. Discovering exactly what those genes are and what specific role they play has proved elusive, until now.
After years of careful work, investigators at the Harvard School of Public Health and Harvard Medical School have discovered a gene that, when absent, significantly increases susceptibility to TB, and perhaps other infections. The gene was found in mice, but it has a counterpart in humans that may act in much the same way.
“The results are encouraging and highlight the role of genes in determining whether or not a person has a high risk of developing tuberculosis,” says Igor Kramnik, assistant professor of immunology and head of the research team. “Finding a specific gene in a mouse that has a human equivalent may lead to diagnostic tests and strategies for prevention. Further studies will also increase our understanding of how our immune system works to protect us against invasions by live pathogens.”