World TB day

World TB Day, falling on March 24th each year, is designed to build public awareness that tuberculosis today remains an epidemic in much of the world, causing the deaths of several million people each year, mostly in developing countries. March 24th commemorates the day in 1882 when Dr Robert Koch astounded the scientific community by announcing that he had discovered the cause of tuberculosis, the TB bacillus. At the time of Koch’s announcement in Berlin, tuberculosis, which usually attacks the lungs, was the single biggest disease threat to humanity.Koch’s discovery opened the way towards diagnosing and curing TB.

The theme of World TB Day 2011 is “On the move against TB: Transforming the fight towards elimination”

Today, about one-third of the world’s population is infected with Mycobacterium tuberculosis (Mtb), the bacterium that causes TB. Most people have no symptoms because the bacterium is inactive, or latent, but individuals with symptoms of active TB disease can infect others. According to World Health Organization (WHO) estimates, in 2009 more than 14 million people had active TB, leading to 1.7 million deaths, or 4,600 deaths each day. Among people infected with the bacteria, those who have certain other conditions, such as HIV/AIDS and diabetes, are more likely to develop active TB and to die from it. Because of this deadly synergy, TB has become the leading cause of death among people with HIV/AIDS.

Symptoms of TB

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.

Risk factors

Anyone can get tuberculosis, but certain factors can increase your risk of the disease. These factors include:

Weakened immune system

A healthy immune system can often successfully fight TB bacteria, but your body can’t mount an effective defense if your resistance is low. A number of diseases and medications can weaken your immune system, including:

HIV/AIDS
Diabetes
End-stage kidney disease
Cancer treatment, such as chemotherapy
Drugs to prevent rejection of transplanted organs
Some drugs used to treat rheumatoid arthritis, Crohn’s disease and psoriasis
Malnutrition
Advanced age
Poverty and substance abuse

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.

[Sources- Mayoclinic.com,Stoptb.org]