Tuberculosis

From TinWiki.org


ats61206_2329880642_3b00a8d920.jpg
Tuberculosis
ats45944_imageinformationiconyt41.gif

Tuberculosis, or TB, is a common and often deadly infectious disease caused by mycobacteria, mainly Mycobacterium tuberculosis. TB normally attacks the lungs but can also affect the central nervous system, the lymphatic system, the circulatory system, the genitourinary system, the gastrointestinal system, bones, joints, and the skin.

Typical symptoms of TB are a chronic cough with bloody sputum, fever, night sweats, and weight loss. TB is generally diagnosed by chest x-rays, skin tests, and sputum cultures. Treatment is difficult and requires long courses of multiple antibiotics.

TB is spread through the air; people who have the disease cough, sneeze, or spit, making the bacteria airborne. One third of the world's current population has been infected with TB bacteria, with new infections occurring at the rate of one per second. Most cases will not turn into the full-blown active disease; asymptomatic, latent infection is most common. About one in ten of the latent infections will progress to the active disease, which if left untreated, kills more than half its victims.

A rising number of people in the developed world are contracting TB due to compromised immune systems caused by immunosuppressive drugs, substance abuse, or AIDS. It is estimated that the US has 25,000 new cases of TB each year, almost half of which occur in immigrants from countries where TB is endemic.

Contents

Other Names

In the past, TB has been called consumption, due to the fact that it seemed to consume people from within, with a bloody cough, pallor, fever, and long, relentless wasting. It has also been called the wasting disease' and the white plague, because sufferers appear markedly pale. Miliary tuberculosis, now commonly called disseminated TB, occurs when the infection invades the circulatory system resulting in lesions which have the appearance of millet seeds on x-ray.

History of the Disease

TB has been present in humans since antiquity. The earliest detection of mycobacterium tuberculosis is in the remains of bison 18,000 years old. It is unclear whether TB originated in cattle and then transferred to humans or diverged from a common ancestor infecting a different species.

Skeletal remains that date from around 7000 BC show prehistoric humans had TB and tubercular decay has been found in the spines of mummies from 3000-2400 BC.

Phthisis is a Greek term for TB. Around 460 BC, Hippocrates identified phthisis as the most widespread disease of the times, involving coughing up blood and fever, which was almost always fatal.

Folklore

Before the Industrial Revolution, TB was sometimes regarded as vampirism; when one member of the family died from it, the other members that were infected would lose their health slowly. People believed that this was caused by the original victim draining life from the other family members. Also, people who had TB exhibited symptoms similar to what people considered to be traits of vampires:

  • Red, swollen eyes
  • Pale skin
  • Extremely low body heat
  • Weak heart
  • Coughing up blood

They believed that the only way for the afflicted person to replenish the loss of blood was by sucking blood.

Another belief attributed TB to being forced to attend fairy revels nightly. The victim wasted away due to lack of rest. This belief was most common when a strong connection was seen between the fairies and the dead.

It was also attributed to the victims being "hagridden". The afflicted were transformed into by horses by witches (hags) to travel to their nightly meetings, hence resulting in a lack of rest.

In the 19th century, TB was romanticized, with many believing TB produced feelings of euphoria. In the early 20th century, some believed that TB was caused by masturbation.

Types of TB

75% of active TB cases stay in the lungs and are defined as pulmonary TB. In 25% of active TB cases, the infection moves from the lungs, causing other types of TB, called extrapulmonary tuberculosis.

  • If TB bacteria moves to central nervous system, it becomes meningitis.
  • If TB bacteria moves to lymphatic system, it becomes scrofula of the neck.
  • If TB bacteria moves to the pleura (the body cavity surrounding the lungs, it becomes tuberculosis pleurisy.
  • If TB bacteria moves to the genitourinary system, it becomes urogenital tuberculosis.
  • If TB bacteria moves to the bones and joints, it becomes Potts disease of the spine.

Extrapulmonary TB is not contagious in and of itself, but it may co-exist with pulmonary TB, which is contagious.

Transmission of the Disease

When people suffering from active pulmonary TB cough, speak, sneeze, or spit, they expel infectious aerosol droplets of bacteria. Each droplet may transmit the disease; inhalation of just a single bacterium can cause a new infection. A person with active but untreated TB can infect 10 to 15 other people per year.

Risk Factors

  • People who live with individuals who have an active TB infection
  • Poor or homeless people
  • Foreign-born people from countries that have a high prevalence of TB
  • Nursing home residents
  • Prison inmates
  • Alcoholics
  • Intravenous drug users
  • People with diabetes, certain cancers, and HIV Infection (the AIDS virus)

Symptoms

  • Generalized tiredness or weakness
  • Weight loss
  • Fever
  • Night sweats
  • Chills
  • Pallor
  • Coughing
  • Chest pain
  • Coughing up of sputum (material from the lungs) and/or blood
  • Shortness of breath

Diagnosis

TB can be diagnosed in several different ways.

  • Chest x-rays
    • Can reveal evidence of active TB pneumonia
    • Can show scarring (fibrosis) in the lungs
    • Can show hardening (calcification) in the lungs
  • Analysis of sputum
    • Can show the presence of TB-like bacteria
    • Samples are often taken and grown (cultured) in special incubators so that the TB bacteria can be identified as TB or atypical TB
  • Skin tests
    • Tine Test
    • Mantoux Test (PPD or purified protein derivative test)
      • In both tests, a small amount of purified extract from dead TB bacteria is injected under the skin
      • If infected, a raised and reddened area will occur around the site of the test injection
      • Positive test reaction occurs about 48 to 72 hours after the injection
  • PCR (polymerase chain reaction)
    • Detects the genetic material of the bacteria
    • Special test for early diagnosis or if the bacteria does not show up clearly on regular tests
    • Extremely sensitive test
    • Detects minute amounts of the bacteria
    • Detects only the TB bacteria
    • Results available within a few days of initial test

Treatments

  • Inactive TB: a person with a positive skin test, a normal chest x-ray, and no symptoms
    • Isoniazid: antibiotic used to keep TB from becoming active
      • Taken for 6 to 12 months
      • Can prevent TB from becoming active in the future
      • Not advisable for women who are pregnant, alcoholics, or people suffering from liver disease
      • Can cause liver damage
      • Can cause peripheral neuropathy (decreased sensation in extremities)
  • Active TB: a person with a positive skin test, an abnormal chest x-ray, and sputum evidencing TB bacteria; contagious
    • Treated with antibiotics
      • Isoniazid
      • Rifampin
      • Ethambutol
    • Injections of Streptomycin: injectible medication given if the disease is extensive or if patient does not take oral medications reliably
    • Treatment lasts for months or years, depending on the severity of the disease
    • Surgery on the lungs
      • Done only if medication has failed
    • Pyrazinamide

External Links


Relevant discussion threads on AboveTopSecret.com

AboveTopSecret.com's threads dedicated to this discussion:
Retrieved from "http://www.tinwiki.org/wiki/Tuberculosis"