What Is Tuberculosis? What Causes Tuberculosis?
When a person becomes infected with tuberculosis, the bacteria in the lungs multiply and cause pneumonia along with chest pain, coughing up blood, and a prolonged cough. In addition, lymph nodes near the heart and lungs become enlarged. As the TB tries to spread to other parts of the body, it is often interrupted by the body's immune system. The immune system forms scar tissue or fibrosis around the TB bacteria, and this helps fight the infection and prevents the disease from spreading throughout the body and to other people. If the body's immune system is unable to fight TB or if the bacteria breaks through the scar tissue, the disease returns to an active state with pneumonia and damage to kidneys, bones, and the meninges that line the spinal cord and brain.
TB is generally classified as being either latent or active. Latent TB occurs when the bacteria are present in the body, but this state is inactive and presents no symptoms. Latent TB is also not contagious. Active TB is contagious and is the condition that can make you sick with symptoms.
TB is a major cause of illness and death worldwide, especially in Africa and Asia. Each year the disease kills almost 2 million people. The disease is also prevalent among people with HIV/AIDS.
What causes tuberculosis?Tuberculosis is ultimately caused by the Mycobacterium tuberculosis that is spread from person to person through airborne particles. It is not guaranteed, though, that you will become infected with TB if you inhale the infected particles. Some people have strong enough immune systems that quickly destroy the bacteria once they enter the body. Others will develop latent TB infection and will carry the bacteria but will not be contagious and will not present symptoms. Still others will become immediately sick and will also be contagious.
What are the symptoms of tuberculosis?Most people who become infected with the bacteria that cause tuberculosis actually do not present symptoms of the disease. However, when symptoms are present, they include unexplained weight loss, tiredness, fatigue, shortness of breath, fever, night sweats, chills, and a loss of appetite. Symptoms specific to the lungs include coughing that lasts for 3 or more weeks, coughing up blood, chest pain, and pain with breathing or coughing.
How is tuberculosis diagnosed?Tuberculosis diagnosis usually occurs after a combination of skin, blood, and imaging tests.
The most common diagnostic test is a simple skin test called the Mantoux test. The Mantoux test consists of a small amount of purified protein derivative (PPD) tuberculin that is injected into the forearm. After 48 to 72 hours, a doctor or nurse looks for a reaction at the injection site; a hard, raised red bump usually indicates a positive test for TB. Blood tests may also be used to determine whether TB is active or latent (inactive), and microscopic sputum analyses or cultures can find TB bacteria in the sputum.
Chest x-rays and computer tomography (CT) scans are also used to diagnose TB. If the immune system traps the TB bacteria and creates scar tissue, this tissue and the lymph nodes may harden like stone in a calcification process. This results in granuloma (rounded marble-like scars) that often appear on x-rays and CT scans. However, if these scars do not show any evidence of calcium on an x-ray, they can be difficult to distinguish from cancer.
Who gets tuberculosis?Tuberculosis is spread from person to person through tiny droplets of infected sputum that travel through the air. If an infected person coughs, sneezes, shouts, or spits, bacteria can enter the air and come into contact with uninfected people who breath the bacteria into their lungs.
Although anyone can become infected with TB, some people are at a higher risk, such as:
- Those who live with others who have active TB infections
- Poor or homeless people
- Foreign-born people who come from countries with endemic TB
- Older people, nursing home residents, and prison inmates
- Alcoholics and intravenous drug users
- Those who suffer from malnutrition
- Diabetics, cancer patients, and those with HIV/AIDS or other immune system problems
- Health-care workers
- Workers in refugee camps or shelters
How is tuberculosis treated?Treatment for TB depends on the whether the disease is active of latent. If TB is in an inactive state, an antibiotic called isoniazid (INH) is prescribed for six to twelve months. INH is not prescribed to pregnant women, and it can cause side effects such as liver damage and peripheral neuropathy.
Active TB is treated with INH as well as drugs such as rifampin, ethambutol, and pyrazinamide. It is also not uncommon for TB patients to receive streptomycin if the disease is extensive. Drug therapies for TB may last many months or even years.
If a patient has a drug-resistant strain of TB, several drugs in addition to the main four are usually required. In addition, treatment is generally much longer and can require surgery to remove damaged lung tissue.
The largest barrier to successful treatment is that patients tend to stop taking their medicines because they begin to feel better. It is important to finish medications in order to completely eradicate the TB bacteria from the body.
How can tuberculosis be prevented?There is a vaccine available for tuberculosis called the BCG vaccine that is used in several parts of the world where TB is common.This vaccine usually protects children and infants from the disease, but adults can still get TB after being vaccinated as children.
Better methods of preventing tuberculosis or TB relapses include eating a healthful diet that takes care of your immune system, getting a TB test regularly if you work or live in a high risk environment, and finishing TB medications. To prevent transmitting the disease to others if you are infected, stay home, cover your mouth, and ensure proper ventilation.