I.

Introduction

Tuberculosis (TB), chronic or acute bacterial infection that primarily attacks the lungs, but which may also affect the kidneys, bones, lymph nodes, and brain. The disease is caused by Mycobacterium tuberculosis, a rod-shaped bacterium. Many people harbor the bacteria but have no symptoms of disease. When symptoms develop, they include coughing, chest pain, shortness of breath, loss of appetite, weight loss, fever, chills, and fatigue. Children and people with weakened immune systems are the most susceptible to TB.

In 1993 the World Health Organization (WHO) declared TB to be a global emergency, the first such designation ever made by that organization. According to WHO, someone becomes infected with the bacteria that cause TB every second. One-third of the world’s population is infected with the bacteria, and as many as one in ten of those infected will develop active symptoms of tuberculosis at some point in their lives. People living with HIV are at much greater risk than others.