Tuberculosis infects nearly ten million people each year and kills nearly two million. It is primarily a lung disease that spreads easily among people with weakened immune systems. Sub-Saharan Africa is still the epicenter of the HIV/AIDS disaster, but it is also becoming the epicenter of tuberculosis.
In Lesotho, a small country in southern Africa, only one in four people is infected with HIV. But that is only one of the threats to health in nation.
"What we also see is a huge co-infection rate. So of all our TB patients, between 80 to 90 percent of them also have HIV," said Helen Bygrave, who is with Doctors without Borders.
Tuberculosis easily infects patients whose immune systems are weakened by HIV.
It spreads when a person coughs, speaks or spits. Those with AIDS have no protection against it.
TB has become the number one killer of African AIDS patients. "We treat it as a dual epidemic. We call it 'double trouble,'" Bygrave said.
The dual epidemics are fueled by crowded conditions.
Pulmonologist Dr. Lee Reichman has worked to control TB for 40 years. "TB spreads wherever people are close together and they share air for a considerable length of time," Reichman said.
When people infected with TB fail to take all of their medicine, tuberculosis can become resistant to the drugs commonly used to fight it.
Dr. Reichman says it doesn't have to be this way. "Multi-drug resistant TB and extensively drug resistant TB are failures of the system. TB is treatable and preventable. And if we find TB properly and treat TB properly, a) they are cured, and b), they don't develop drug resistant TB, whether it be multi-drug or extensive drug," he said.
A lot has to change to turn the situation around. Dr. Reichman says because TB is highly contagious, and because it co-exists with other infectious diseases, all countries, rich and poor need to pay attention. "Because TB is everybody's problem, and to control TB anywhere, you have to control TB everywhere," he said.
Eradicating TB by 2015 is one of the millennium goals of the World Health Organization.
In Lesotho, the task is enormous. But if it doesn't happen, experts warn, drug resistant TB will become far more common everywhere.