Tuberculosis first received its name during the 17th century by Franciscus de la Boe. But before Tuberculosis was given its name, it was commonly referred to as: Consumption, Mesenteric disease, Phthisis, Pottís disease, Scrofula, White Plague, and White swelling (1). Tissue samples retrieved 5,400 year ago first gave proof that humans had contracted the disease (1). However, tuberculosis was documented way back to 3400 B.C. which was found in a pre-dynastic Egyptian mummy (1). In 1882, Robert Koch discovered tuberculosis bacillus (1). Tuberculosis was named after the "tubercles" that were first associated with the disease (1).
The etiologic agent that is responsible for causing tuberculosis is the organism Mycobacterium tuberculosis; it is a straight or slightly curved rod about 0.2 to 0.7 x 10-10 mcm (7). Its growth pattern branches and is mycelium like (7). The bacterium is strongly acid-fast, and at young stages is acid-alcohol-fast; there is also a weak degree of gram staining (7). The growth rate, in which visible colonies can be seen, is between 2 and 60 days (7). Tuberculosis is contracted and spread by coughing or aerosolization, which are droplets containing M. tuberculosis sprayed into the air (2). Because the disease does not only involve direct transmission, one person can put several other individuals at risk (10).
The main reservoirs of tuberculosis today are humans. However, the disease was originally found in the soil (6). The primary mode of transmission is when an infected individual releases droplets from sneezing or coughing (2). On the other hand, a case reported said an embalmer contracted the disease after performing an autopsy on a cadaver (8). There are two important factors that influence the epidemiology of tuberculosis. The first is that there needs to be exposure to tuberculosis in the environment. Risk factors for getting a tuberculosis infection require having contact with a source case (4). The second factor that leads to a tuberculosis infection is a susceptibility to disease after an initial infection (4).
There are a number of conditions that increase the hostís chance of developing active Tuberculosis (4). They include: HIV infection, age, cancer, diabetes, and diet (4). The body has a limited defenses system that aids in preventing the bacteria from growing in our lungs. Among these are upper airways filtering systems, mucociliary escalator clearing the organisms, and the killing of the organisms with the macrophages that reside in the alveoli (4). Virulence factors associated with M. tuberculosis are cord factor, muramyl dipeptide, prevention of phagolysosome fusion, mycolic acid, polyanionic trehalise sulfates, intracellular growth, wax D, sulphatides, and granuloma formation (10).
Only thirty percent of people exposed to the M. tuberculosis bacterium actually acquire the infection (4). Once in the hostís lungs, the bacilli begin to replicate. This stage of the disease process usually has no symptoms (4). Within two year a small percentage of people infected will develop an active clinical disease (4). Most tuberculosis infections remain latent for years. Many will never develop clinical disease (4). The most common test for diagnosing tuberculosis is the administration of purified protein derivative (PPD) (4). The PPD is given in the Mantoux method and the reaction is read at 24 to 72 hours (4). A reaction for the general public is considered positive at a diameter of 15mm or greater; for people having a moderate to high probability of having a tuberculosis infection, such as people from endemic areas, IV drug users, and people with medical conditions, a diameter of greater than 10mm is considered positive; and for people with a high probability of infection due to close contact with infected persons, HIV infected people, and young children, a diameter of 5mm is considered positive (4). If the PPD test is positive other tests to confirm a tuberculosis infection might include chest x-rays, sputum cultures, bronchoscopy, and open lung biopsy (2).
When a tuberculosis infection occurs, symptoms may not be obvious or they might be limited to a mild fever or a minor cough (2). As tuberculosis develops, the symptoms might include fatigue, weight loss, coughing up blood, slight fever and night sweats (2). In an acute tuberculosis infection, additional symptoms include wheezing, rales, excessive sweating, join pain, hearing loss, diarrhea, chest pain, breathing difficulty, positive Babinski reflex, and clubbing of the fingers or the toes (2). The Centers for Disease Control reports the incidence of tuberculosis yearly in the MMWR (9). The 1999 MMWR reported that the incidence of tuberculosis was less than 3.5 cases per 100,000 in population (9). MMWR reports shows the number of cases have fluctuated throughout history (9). Mortality was high until the 1940ís when antibiotic therapy became available for the treatment of tuberculosis (1).
Tuberculosis is primarily controlled by a multi-drug regimen that is active against the M. tuberculosis organism (4). A culture and sensitivity should always be run from the initial isolates. The Centers for Disease Control and Prevention recommends that therapy should initially be given with four drugs: isoniazid, rifampin, pyrazinamide, and ethambutol or streptomycin (4). The dosages will vary in consideration of the time intervals given and the age of the patient (4). A vaccine for tuberculosis is called Bacillus of Calmette and Guerin (BCG) (3). The use of this vaccination as a prevention is only used in a small selected portion of the population. Groups that will meet the criteria include children and infants that who live in high risk settings and health care workers who are employed where transmission is likely (3). The use of BCG in the United States is limited, and is not recommended for most health care workers (3). Tuberculosis is best be prevented by isolating and treating infected people.
Over the years tuberculosis has killed millions of people. It is an infectious disease that is transmitted from person to person. Once diagnosed, tuberculosis is treated with a multi-drug regimen for six to twelve months. Since the identification of tuberculosis, treatments and therapy have been developed to combat the disease; however, a cure and the elimination of tuberculosis is a long way off (2). Tuberculosis is a pandemic disease and it continues to be a threat to people around the world.
References
1. "The History of Human Tuberculosis". 8/9/01. URL: http://www.wits.ac.za/fac/med/mol_bio/noframe/no_history.htm. accessed 04/28/02.
2. "Pulmonary Tuberculosis". 1999. URL: http://content.health.msn.com/content/asset/adam_disease_pulmonary_tuberculosis. accessed 04/28/02.
3. Advisory Council for the Elimination of Tuberculosis. "The Role of the BCG Vaccine in the prevention and Control of Tuberculosis". 4/26/96. URL: http://www.cdc.gov/mmwr/preview/mmwrhtml/00041047.htm. accessed 04/29/02
4. Chaisson, Richard E. "Tuberculosis".1997. URL: http://hopkins-id.edu/diseases/tb/tb.html. accessed 04/27/02.
5. "Brief History of Tuberculosis". 7/23/96. URL: http://www.umdnj.edu/~ntbcwed/history.htm. accessed 04/30/02.
6. "Epidemic". 1999. URL: http://www.discovery.com/exp/epidemic/tb/tbzoom1.html. accessed 04/30/02.
7. Holt, John G., Noel R. Krieg, Peter H.A. Sneath, James T. Staley, and Stanley T. Williams. Bergeyís Manuel of Determinative Bacteriology. Ninth ed. William R. Hensyl ed. Baltimore: Williams and Wilkins, 1994. p 597-9.
8. JAMA. "Tuberculosis Spread by Corpse". 1/18/00 URL: http://www.ama-assn.org/special/hiv/newsline/cdc/012700g1.htm. accessed 05/01/02.
9. Centers for Disease Control. "Summary of Notifiable Diseases, United States 1999". 1999. URL: http://www.cdc.gov/mmwr/preview/mmwrhtml/mm4853a1.htm. accessed 05/01/02.
10. "Mycobacterium Tuberculosis". 8/16/99. URL: http://www.medinfo.ufl.edu/year2/mmid/bms5300/bugs/mycotubr.html. accessed 05/01/02.