Tuberculosis

Definition

Tuberculosis (TB) is a potentially fatal contagious disease that can affect almost any part of the body but is mainly an infection of the lungs. It is caused by a bacterial microorganism: the tubercle bacillus or Mycobacterium tuberculosis. Although TB can be treated and cured, and can be prevented if persons at risk take certain drugs, medical science has never succeeded in eradicating the disease. Few diseases have caused so much distressing illness for centuries and claimed so many lives.

Overview

Tuberculosis was popularly known as consumption for many years. Scientists now know that it is an infection caused by M. tuberculosis. In 1882, one of every seven deaths in Europe was caused by TB. In that year, the microbiologist Robert Koch discovered the tubercle bacillus. Because antibiotics were unknown, the only means of controlling the spread of infection was to isolate patients in private sanitariums or hospitals limited to treating persons with TB. In many countries, this practice continues to this day. The net effect of this approach to treatment was to separate the study of tuberculosis from mainstream medicine. Entire organizations were set up to study not only the disease as it affected individual persons, but also its impact on society as a whole. At the turn of the twentieth century, more than 80% of the population in the United States was infected with TB before age 20, and tuberculosis was the single most common cause of death. By 1938, there were more than 700 TB hospitals in the United States.

When the industrial revolution began in the late nineteenth century, tuberculosis spread much more widely in Europe. Later, the disease began to spread throughout the United States, primarily due to the population migration to large cities that made overcrowded housing so common. When streptomycin, the first antibiotic effective against M. tuberculosis, was discovered in the early 1940s, the infection began to come under control. Although other, more effective anti-tuberculosis drugs were developed in the following decades, the number of cases of TB in the United States began to rise again in the mid-1980s. In part, this upsurge was again a result of overcrowding and unsanitary conditions in poor areas of large cities, prisons, and homeless shelters. Infected visitors and immigrants to the United States also contributed to the resurgence of TB. An additional factor was the emergence of acquired immunodeficiency syndrome (AIDS). Persons with AIDS are much more likely to develop tuberculosis because of their weakened immune systems than are others in the general population. As of 2001, experts estimate that between 8 and 11 million new cases of TB are reported each year throughout the world. These are estimated to cause approximately 3 million deaths. This situation is worsening. The World Health Organization estimates that by 2020, there will be 1 billion TB cases worldwide and 35 million deaths each year.