When the immune system is weakened by the AIDS virus, people become vulnerable to many other infections. In parts of the world where both TB and AIDS are widespread, the number of people with both diseases is rising rapidly. This creates problems that are far greater than those of either disease on its own. NPR's Richard Harris reports from Nairobi, Kenya, where one small clinic is testing the idea of treating both diseases at the same time. (9:30) NPR News provides expanded coverage.