What is TB?
Tuberculosis is caused by an infection with Mycobacterium tuberculosis, rod-shaped bacteria that are spread mostly through air-born droplets or dust micro-particles of dried sputum. Once inhaled, the body’s immune system typically reacts by engulfing the bacteria, forming a tubercle that contains the bacteria to help keep it from spreading. In most cases, the bacteria will die; in others, however, the bacteria can survive, become dormant, and the infected individual may develop active disease at a later date, sometimes soon after infection, sometimes years later.
Those who develop active pulmonary tuberculosis experience a range of signs and symptoms, including chest pain, cough, weight loss, pallor, fever, and night sweats. People with suppressed immune systems, such as persons with HIV and AIDS, are much more likely to develop active tuberculosis.
Only those with active pulmonary TB are able to spread it, by coughing or sneezing. These actions release the bacteria from the lungs into the air, where it can be inhaled by others. The bacteria are able to survive in the air for several hours, but are weakened by direct sunlight.
The bacteria are transmitted from person to person most easily in crowded conditions. Living situations where many individuals live in close proximity to each other exacerbate the likelihood of disease transmission. Malnutrition and alcoholism can also facilitate the transmission of the disease by weakening an individual’s immune response.
Tuberculosis has affected humans for thousands of years. Egyptian tomb paintings depict people with signs of tuberculosis, and writers from Ancient India,Greece and Rome described the ailment.
Image 1: After it was discovered that disease, generally speaking, was spread by germs, new public health measures were taken to halt the spread of disease. In the case of tuberculosis, one of these measures was to outlaw spitting in the streets. Tuberculosis patients were to carry sputum flasks with them and to spit into these instead of onto the streets, where the bacteria from their expectorations could be spread to others.
Treatments have taken many forms throughout the ages, but it was not until after Robert Koch found the cause of the disease in 1882 that a cure to the bacterial infection was found. Over the years treatments have included being touched by royalty, fresh air and rest in a sanatorium, and pneumothorax treatments (i.e. collapsing a lung). The first effective vaccine against the disease, developed by Albert Calmette and Camille Guérin, was first used clinically with humans in 1921, and continues to be used around the world today. A string of advances in chemotherapy occurred mid-century. Selman Waksman demonstrated the effects of streptomycin in 1944, and this was followed by the discovery of para-aminosalicylic acid in 1948, isoniazid in 1952, and rifampin in 1966. Since this time drug regimens have been the primary treatment for tuberculosis.
Image 2: Norman Bethune improved on the pneumothorax machine after undergoing this operation himself as a patient at the Saranac Lake Sanatoria in northern New York State. During a pneumothorax procedure air or fluid is introduced into the pleural space, the space between the membranes attached to the lung and to the chest. The increased pressure in this space causes the lung to collapse. This helped tuberculosis patients improve because at rest the body could heal the lung tissue more effectively.
For more information on the history of Tuberculosis in Canada see http://www.lung.ca/tb/index.html & watch for the upcoming online exhibition on tuberculosis, presented by the Museum of Health in the fall of 2012.