Up

Tuberculosis

Tuberculosis

Tuberculosis (TB) describes an infectious disease that has plagued humans since the Neolithic times. Two organisms cause tuberculosis - Mycobacteriumtuberculosis and Mycobacteriumbovis.

 

Physicians in ancient Greece called this illness "phthisis" to reflect its wasting character. During the 17th and 18th centuries, TB caused up to 25% of all deaths in Europe. In more recent times, tuberculosis has been called "consumption".

 

  • Robert Koch isolated the tubercle bacillus in 1882 and established TB as an infectious disease.
  1. In the 19th century, patients were isolated in sanatoria and given treatments such as injecting air into the chest cavity. Attempts were made to decrease lung size by surgery called thoracoplasty.
  2. During the first half of the 20th century, no effective treatment was available.
  3. Streptomycin, the first antibiotic to fight TB, was introduced in 1946, andisoniazid (Laniazid, Nydrazid), originally an antidepressant medication, became available in 1952.
  • M. tuberculosis is a rod-shaped, slow-growing bacterium.
  1. M. tuberculosis' cell wall has high acid content, which makes it hydrophobic, resistant to oral fluids.
  2. The cell wall of Mycobacteria absorbs a certain dye used in the preparation of slides for examination under the microscope and maintains this red color despite attempts at decolorization, hence the name acid-fast bacilli.
  • M. tuberculosis continues to kill millions of people yearly worldwide. In 1995, 3 million people died from TB.
  1. More than 90% of TB cases occur in developing nations that have poor hygiene and health-care resources and high numbers of people infected with HIV.
  • In the United States, the incidence of TB began to decline around 1900 because of improved living conditions.
  1. TB cases have increased since 1985, most likely due to the increase in HIV infection.
  • Tuberculosis continues to be a major health problem worldwide. In 2008, the World Health Organization (WHO) estimated that one-third of the global population was infected with TB bacteria.
  1. 8.8 million new cases of TB developed.
  2. 1.6 million people died of this disease in 2005.
  3. Each person with untreated active TB will infect on average 10-15 people each year.
  4. A new infection occurs every second.
  5. In 2009, the TB rate in the United States was 3.8 cases per 100,000 population, a slight decrease from the prior year. Four states (California, Florida, New York, and Texas) accounted for the majority of all new TB cases (50.3%).
  • With the spread of AIDS, tuberculosis continues to lay waste to large populations. The emergence of drug-resistant organisms threatens to make this disease once again incurable.
  • In 1993, the WHO declared tuberculosis a global emergency.

Symptoms

You may not notice any symptoms of illness until the disease is quite advanced. Even then the symptoms - loss of weight, loss of energy, poor appetite, fever, a productive cough, and night sweats - might easily be blamed on another disease.

 

  • Only about 10% of people infected with M. tuberculosis ever develop tuberculosis disease. Many of those who suffer TB do so in the first few years following infection, but the bacillus may lie dormant in the body for decades.
  • Although most initial infections have no symptoms and people overcome them, they may develop fever, dry cough, and abnormalities that may be seen on a chest X-ray.
  1. This is called primary pulmonary tuberculosis.
  2. Pulmonary tuberculosis frequently goes away by itself, but in 50%-60% of cases, the disease can return.
  • Tuberculous pleuritis may occur in 10% of people who have the lung disease from tuberculosis.
  1. The pleural disease occurs from the rupture of a diseased area into thepleural space, the space between the lung and the lining of the abdominal cavity.
  2. These people have a nonproductive cough, chest pain, and fever. The disease may go away and then come back at a later date.
  • In a minority of people with weakened immune systems, TB bacteria may spread through their blood to various parts of the body.
  1. This is called miliary tuberculosis and produces fever, weakness, loss of appetite and weight loss.
  2. Cough and difficulty breathing are less common.
  • Generally, return of dormant tuberculosis infection occurs in the upper lungs. Symptoms include
  1. common cough with a progressive increase in production of mucus and
  2. coughing up blood.
  3. Other symptoms include the following:

- fever,

- loss of appetite,

- weight loss,

- night sweats.

  • About 15% of people may develop tuberculosis in an organ other than their lungs. About 25% of these people usually had known TB with inadequate treatment. The most common sites include the following:
  1. lymph nodes,
  2. genitourinary tract,
  3. bone and joint sites,
  4. meninges,
  5. the lining covering the outside of the gastrointestinal tract.

Causes

All cases of TB are passed from person to person via droplets. When someone with TB infection coughs, sneezes, or talks, tiny droplets of saliva or mucus are expelled into the air, which can be inhaled by another person.

 

  • Once infectious particles reach the alveoli (small saclike structures in the air spaces in the lungs), another cell, called the macrophage, engulfs the TB bacteria.
  1. Then the bacteria are transmitted to the lymphatic system and bloodstream and spread to other organs occurs.
  2. The bacteria further multiply in organs that have high oxygen pressures, such as the upper lobes of the lungs, the kidneys, bone marrow, andmeninges -- the membrane - like coverings of the brain and spinal cord.
  • When the bacteria cause clinically detectable disease, you have TB.
  • People who have inhaled the TB bacteria, but in whom the disease is controlled, are referred to as infected. Their immune system has walled off the organism in an inflammatory focus known as a granuloma. They have no symptoms, frequently have a positive skin test for TB, yet cannot transmit the disease to others. This is referred to as latent tuberculosis infection or LTBI.
  • Risk factors for TB include the following:
  1. HIV infection,
  2. low socioeconomic status,
  3. alcoholism,
  4. homelessness,
  5. crowded living conditions,
  6. diseases that weaken the immune system,
  7. migration from a country with a high number of cases,
  8. health-care workers.

Treatment

Today, doctors treat most people with TB outside the hospital. Gone are the days of going to the mountains for long periods of bed rest.

 

Doctors seldom use surgery.

 

  • Doctors will prescribe several special medications that you must take for six to nine months.
  1. Standard therapy for active TB consists of a six-month regimen:

- two months with Rifater (isoniazid,rifampin, and pyrazinamide);

- four months of isoniazid and rifampin (Rifamate, Rimactane);

- and ethambutol (Myambutol) or streptomycin added until your drug sensitivity is known (from the results of bacterial cultures).

  1. Treatment takes that long because the disease organisms grow very slowly and, unfortunately, also die very slowly. (Mycobacterium tuberculosis is a very slow-growing organism and may take up to six weeks to grow in a culture media.)
  2. Doctors use multiple drugs to reduce the likelihood of resistant organisms emerging.
  3. Often the drugs will be changed or chosen based on the laboratory results.

- If doctors doubt that you are taking your medicine, they may have you come to the office for doses. Prescribing doses twice a week helps assure compliance.

- The most common cause of treatment failure is people's failure to comply with the medical regimen. This may lead to the emergence of drug-resistant organisms. You must take your medications as directed, even if you are feeling better.

  • Another important aspect of tuberculosis treatment is public health. This is an area of community health for which mandated treatment can occur. In some cases, the local health department will supervise administration of the medication for the entire course of therapy.
  1. Doctors likely will contact or trace your relatives and friends.
  2. Your relatives and friends may need to undergo appropriate skin tests and chest X-rays.
Enter through
Enter through