Dave MartinTuberculosis (TB) Wednesday, July 14, 2011What is Tuberculosis?TB is a bacterial infection caused by the bacteria Mycobacterium Tuberculosis or TubercleBacillus. It attacks the lining of the lungs causing lesions which in tune cause bleeding coughingspells. Beginning with infections in the upper part of the lower lobe or the lower part of theupper lobe it spreads through the blood stream to other organs.Secondary TB lesions can develop in peripheral lymph nodes, kidneys, brain or bone. In fact, allparts of the body can be affected by TB, however the heart, pancreas, thyroid and skeletalmuscles are rarely affected. 90% of people who are infected with TB are infected with LatentTB. That is, the infecting bacteria remain dormant in the body, inactive; no symptoms areevident and the carrier is not contagious. The carrier is however at risk of developing Active TB.Active TB will develop in patients with a weakened immune system causing symptoms and thecarrier will become contagious. 10% of people with Latent TB develop active cases of thedisease. Active TB is most common in people with HIV. Recent immigrants from countrieswhere TB is widespread and those who live in inner cities are more likely to be carriers of TB.Tuberculosis continues to be a major health problem worldwide. In 2008, the World HealthOrganization estimated that one third of the global population was infected with TB bacteria.How do you get it?By inhaling minute particles, of infected sputum from the air, one can obtain the tuberculosisdisease. The bacteria get into the air when someone who has a tuberculosis lung infection:coughs, sneezes, shouts, or spits (which is common in some cultures). When people sufferingfrom active pulmonary TB, cough, sneeze, speak, sing, or spit, they expel infectious aerosol
Dave Martindroplets 0.5 to 5 µm in diameter. A single sneeze can release up to 40,000 droplets. Since theinfectious dose of tuberculosis is very low, and inhaling fewer than ten bacteria may cause aninfection, each one of these droplets may transmit the disease. There is a form of atypicaltuberculosis, which transmitted by drinking unpasteurized milk. Related bacteria, calledMycobacterium bovis, cause this form of TB. Previously, this type of bacteria was a major causeof TB in children, but it rarely causes TB now since most milk is pasteurized (undergoes aheating process that kills the bacteria).How do you treat it?The standard "short" course treatment for TB is isoniazid (an antibiotic that kills the bacteria thatcauses TB), rifampicin (also known as rifampin in the United States), pyrazinamide, andethambutol for two months, followed by isoniazid and rifampicin alone for another four months.At six months (although there is still a relapse rate of 2 to 3%), the patient is considered cured.History:TB was commonly known as Consumption in the 18th and 19th centuries, due to its wastingaway of victims. It was first isolated in 1882 by a German physician named Robert Koch, whoreceived the Nobel Prize for this discovery. Other names include phthisis (Greek forconsumption) and phthisis pulmonalis; scrofula (in adults), affecting the lymphatic system andresulting in swollen neck glands; tabes mesenterica, TB of the abdomen and lupus vulgaris, TBof the skin; wasting disease; white plague, because sufferers appear markedly pale; kings evil,because it was believed that a kings touch would heal scrofula; and Potts disease, or gibbus ofthe spine and joints.Tuberculosis has been present in humans since antiquity. The earliest unambiguous detection ofMycobacterium tuberculosis is in the remains of bison dated 18,000 years before the present.Whether tuberculosis originated in cattle and then transferred to humans, or diverged from acommon ancestor infecting a different species, is currently unclear. However, it is clear that M.
Dave Martintuberculosis is not directly descended from M. bovis, which seems to have evolved relativelyrecently.Skeletal remains from a Neolithic Settlement in the Eastern Mediterranean show prehistorichumans (7000 BC) had TB, and tubercular decay has been found in the spines of mummies from3000–2400 BC. Phthisis is a Greek term for tuberculosis; around 460 BC, Hippocrates identifiedphthisis as the most widespread disease of the times involving coughing up blood and fever,which was almost always fatal. In South America, the earliest evidence of tuberculosis isassociated with the Paracas-Caverna culture (circa 750 BC to circa 100 AD). Suzanne AustinAlchon wrote that, skeletal remains from prehistoric North America indicate that the disease wasso common that virtually every member of these late prehistoric communities had primaryexposure to tuberculosis.The oldest known human remains showing signs of tuberculosis infection are over 9,000 yearsold. During this period, M. tuberculosis has lost numerous coding and non-coding regions in itsgenome, losses that can be used to distinguish between strains of the bacteria. The implication isthat M. tuberculosis strains differ geographically, so their genetic differences can be used to trackthe origins and movement of each strain.Folklore:Before the Industrial Revolution, tuberculosis was sometimes regarded as vampirism. When onemember of a family died from it, the other members that were infected would lose their healthslowly. Folklore held that this was caused by the original victim draining the life from the otherfamily members. Furthermore, people who had TB exhibited symptoms similar to what peopleconsidered to be vampire traits. People with TB often have symptoms such as red, swollen eyes(which also creates a sensitivity to bright light), pale skin, extremely low body heat, a weak heartand coughing blood, suggesting the idea that the only way for the afflicted to replenish this lossof blood was by sucking blood. Another folk belief told that the affected individual was beingforced, nightly, to attend fairy revels, so that the victim wasted away owing to lack of rest; this
Dave Martinbelief was most common when a strong connection was seen between the fairies and the dead.Similarly, but less commonly, it was attributed to the victims being "hagridden"—beingtransformed into horses by witches (hags) to travel to their nightly meetings, again resulting in alack of rest.TB was romanticized in the nineteenth century. Many people believed TB produced feelings ofeuphoria referred to as Spes phthisica ("hope of the consumptive"). It was believed that TBsufferers who were artists had bursts of creativity as the disease progressed. It was also believedthat TB sufferers acquired a final burst of energy just before they died that made women morebeautiful and men more creative.Epidemiology:Roughly a third of the worlds population has been infected with M. tuberculosis, and newinfections occur at a rate of one per second. However, not all infections with M. tuberculosiscause TB disease and many infections are asymptomatic. In 2007, an estimated 13.7 millionpeople had active TB disease, with 9.3 million new cases and 1.8 million deaths; the annualincidence rate varied from 363 per 100,000 in Africa to 32 per 100,000 in the Americas.Tuberculosis is the worlds greatest infectious killer of women of reproductive age and theleading cause of death among people with HIV/AIDS.The rise in HIV infections and the neglect of TB control programs have enabled a resurgence oftuberculosis. The emergence of drug-resistant strains has also contributed to this new epidemicwith, from 2000 to 2004, 20% of TB cases being resistant to standard treatments and 2%resistant to second-line drugs. The rate at which new TB cases occur varies widely, even inneighboring countries, apparently because of differences in health care systems.In 2007, the country with the highest estimated incidence rate of TB was Swaziland, with 1200cases per 100,000 people. India had the largest total incidence, with an estimated 2.0 million newcases. In developed countries, tuberculosis is less common and is mainly an urban disease. In theUnited Kingdom, the national average was 15 per 100,000 in 2007, and the highest incidencerates in Western Europe were 30 per 100,000 in Portugal and Spain. These rates compared with98 per 100,000 in China and 48 per 100,000 in Brazil. In the United States, the overall
Dave Martintuberculosis case rate was 4 per 100,000 persons in 2007. In Canada tuberculosis is still endemicin some rural areas.Demographics:In the United States, the incidence of TB began to decline around 1900 because of improvedliving conditions. TB cases have increased since 1985, most likely due to the increase in HIVinfection. Mycobacterium Tuberculosis (M. Tuberculosis) continues to kill millions of peopleyearly worldwide. In 1995, 3 million people died from TB worldwide. More than 90% of TBcases occur in developing nations that have poor hygiene and health-care resources and highnumbers of people infected with HIV. 8.8 million new cases of TB are developing each year. 1.6million people died of this disease in 2005. Each person with untreated active TB will infect onaverage 10-15 people each year. A new infection occurs every second. In 2009, the TB rate inthe United States was 3.8 cases per 100,000 population, a slight decrease from the prior year.California, Florida, New York, and Texas accounted for the majority of all new TB cases(50.3%) primarily due to the unchecked illegal immigration from Mexico.
Dave MartinBibliographyPulmonary tuberculosis www.ncbi.nlm.nih.govTuberculosis - Wikipedia en.wikipedia.org/wiki/TuberculosisTuberculosis (TB) Symptoms, Cause, Transmission, Diagnosis and Treatment www.medicinenet.com/tuberculosis/article.htmCDC - Tuberculosis (TB) www.cdc.gov/tb/Tuberculosis: MedlinePlus www.nlm.nih.gov/medlineplus/tuberculosis.html http://en.wikipedia.org/wiki/Tuberculosis - cite_note-Hershkovitz_2008-122Wikipedia: Tuberculosis TreatmentWikipedia: TuberculosisE Medicine HealthInsel, Paul M., and Walton T. Roth. Core Consepts in Health. 11th ed. San Francisco: The McGraw-Hill Companies, 2010. 324-25. Print.http://infectiousdiseases.about.com/od/respiratoryinfections/a/active_tb.htm