Tuberculosis

Tuberculosis

Definition:

Tuberculosis (TB) is a potentially serious infectious disease that primarily affects your lungs. The bacteria that cause tuberculosis are spread from person to person through tiny droplets released into the air via coughs and sneezes.

Tuberculosis was once rare in developed countries, but the number of TB cases began increasing in 1985. Part of the increase was caused by the emergence of HIV, the virus that causes AIDS. HIV weakens a person's immune system so it can't fight the TB germs.

Many strains of tuberculosis can resist the effects of the drugs most commonly used to treat the disease. People who have active tuberculosis must take several different types of medications together for many months to eradicate the infection and prevent development of antibiotic resistance.

Symptoms:

Although your body may harbor the bacteria that cause tuberculosis, your immune system usually can prevent you from becoming sick. For this reason, doctors make a distinction between:

• Latent TB. In this condition, you have a TB infection, but the bacteria remain in your body in an inactive state and cause no symptoms. Latent TB, also called inactive TB or TB infection, isn't contagious.
  
• Active TB. This condition makes you sick and can spread to others. It can occur in the first few weeks after infection with the TB bacteria, or it might occur years later. Most people infected with TB germs never develop active TB.

Signs and symptoms of active TB include:

• Cough
• Unexplained weight loss
• Fatigue
• Fever
• Night sweats
• Chills
• Loss of appetite

What organs are affected?
Tuberculosis usually attacks your lungs. Signs and symptoms of TB of the lungs include:

• Coughing that lasts three or more weeks
• Coughing up blood
• Chest pain, or pain with breathing or coughing

But tuberculosis can also affect other parts of your body, including your kidneys, spine or brain. When TB occurs outside your lungs, symptoms vary according to the organs involved. For example, tuberculosis of the spine may give you back pain, and tuberculosis in your kidneys might cause blood in your urine.

When to see a doctor
See your doctor if you have a fever, unexplained weight loss, drenching night sweats or a persistent cough. These are often signs of TB, but they can also result from other medical problems. Your doctor can perform tests to help determine the cause.

Causes:

Tuberculosis is caused by bacteria that spread from person to person through microscopic droplets released into the air. This can happen when someone with the untreated, active form of tuberculosis coughs, speaks, sneezes, spits, laughs or sings.

Although tuberculosis is contagious, it's not especially easy to catch. You're much more likely to get tuberculosis from someone you live with or work with than from a stranger. Most people with active TB who've had appropriate drug treatment for at least two weeks are no longer contagious.

HIV and TB
Since the 1980s, the number of cases of tuberculosis has increased dramatically because of the spread of HIV, the virus that causes AIDS. Tuberculosis and HIV have a deadly relationship — each drives the progress of the other.

Infection with HIV suppresses the immune system, making it difficult for the body to control TB bacteria. As a result, people with HIV are many times more likely to get TB and to progress from latent to active disease than are people who aren't HIV-positive.

Drug-resistant TB
Another reason tuberculosis remains a major killer is the increase in drug-resistant strains of the bacterium. Ever since the first antibiotics were used to fight tuberculosis 60 years ago, the germ has developed the ability to survive attack, and that ability gets passed on to its descendants. Drug-resistant strains of tuberculosis emerge when an antibiotic fails to kill all of the bacteria it targets. The surviving bacteria become resistant to that particular drug and frequently other antibiotics as well.


Complications:

Without treatment, tuberculosis can be fatal. Untreated active disease typically affects your lungs, but it can spread to other parts of the body through your bloodstream. Examples include:

• Bones. Spinal pain and joint destruction may result from TB that infects your bones. In many cases, the ribs are affected.
  
• Brain. Tuberculosis in your brain can cause meningitis, a sometimes fatal swelling of the membranes that cover your brain and spinal cord.
  
• Liver or kidneys. Your liver and kidneys help filter waste and impurities from your bloodstream. These functions become impaired if the liver or kidneys are affected by tuberculosis.
  
• Heart. Tuberculosis can infect the tissues that surround your heart, causing inflammation and fluid collections that may interfere with your heart's ability to pump effectively. This condition, called cardiac tamponade, can be fatal.

Treatments and drugs:

Medications are the cornerstone of tuberculosis treatment. But treating TB takes much longer than treating other types of bacterial infections. With tuberculosis, you must take antibiotics for at least six to nine months. The exact drugs and length of treatment depend on your age, overall health, possible drug resistance, the form of TB (latent or active) and its location in the body.

Most common TB drugs
If you have latent tuberculosis, you may need to take just one type of TB drug. Active tuberculosis, particularly if it's a drug-resistant strain, will require several drugs at once. The most common medications used to treat tuberculosis include:

• Isoniazid
• Rifampin (Rifadin, Rimactane)
• Ethambutol (Myambutol)
• Pyrazinamide

Medication side effects
Side effects of TB drugs aren't common but can be serious when they do occur. All tuberculosis medications can be highly toxic to your liver. When taking these medications, call your doctor immediately if you experience any of the following:

• Nausea or vomiting
• Loss of appetite
• A yellow color to your skin (jaundice)
• Dark urine
• A fever that lasts three or more days and has no obvious cause

Completing treatment is essential
After a few weeks, you won't be contagious and you may start to feel better. It might be tempting to stop taking your TB drugs. But it is crucial that you finish the full course of therapy and take the medications exactly as prescribed by your doctor. Stopping treatment too soon or skipping doses can allow the bacteria that are still alive to become resistant to those drugs, leading to TB that is much more dangerous and difficult to treat.

To help people stick with their treatment, a program called directly observed therapy (DOT) is sometimes recommended. In this approach, a health care worker administers your medication so that you don't have to remember to take it on your own.