When people hear the word “tuberculosis” many think it is one of the diseases from the dark ages and no longer a threat.  In fact, tuberculosis (TB) is the second largest killer (behind AIDS) in the world from a single infectious agent.[2]  In the United States, an estimated 10-15 million people are infected with the TB bacteria and each year 22,000 new cases of TB occur.[2]  Most of those people have latent TB which means it is dormant and won’t necessarily cause illness.  Those who have the latent disease have a ten percent risk of falling ill with TB over their lifetime.[7]  Those with HIV or any other illness which has affected their immune system are at a higher risk to contract TB.

What is TB?

Tuberculosis is an infectious disease and is caused by the bacteria Mycobacterium tuberculosis.  In 1882, German physicist Robert Koch isolated the bacteria and received a Nobel Prize for his discovery.  Although TB is most common in the lungs, it can infect almost any organ in the body.  In the past, the disease was often referred to as “consumption” due to patients wasting away from lack of treatment of the disease.  Probably the most famous case of consumption was the infamous Doc Holliday.

What Causes TB?

TB bacteria are airborne agents; therefore, people contract this disease from others by breathing in the bacteria released when an infected person coughs, sneezes, spits, sings or shouts.[4]  The bacterium is present in the sputum as minute particles which are inhaled into the lungs.  TB is not transmitted through touching an infected person.

Once the bacteria are inhaled into the lungs, they multiply and can cause pneumonia.  Lymph nodes associated with the lungs can become enlarged.  The bacteria often travel to the lymph nodes adjacent to the heart and can spread throughout the body if not treated.   The immune system is able to fight the bacteria in most cases, but those with illnesses such as HIV which weaken the immune system usually are unable to fight off the TB bacteria.  When the immune system attacks the bacteria, it forms scar tissue around the TB bacteria and contains it in an inactive state. If the TB occurs before the immune system has a chance to do this, it is considered primary TB.  If the immune system is able to act first, the person usually doesn’t have symptoms and is not contagious.

Transmission of TB Bacteria; Courtesy of Center for Disease Control (CDC) Source: Wikimedia CommonsCredit: Photo courtesy of Center for Disease Control (CDC) Source: Wikimedia Commons

Brief animation of TB transmission

Sometimes the immune system weakens and allows the bacteria to escape the scar tissue and “reactivate” the TB.  This is referred to as secondary TB or reactivation tuberculosis.  The immune system can be weakened by:

  • Old age
  • Cancer
  • Another infection
  • Certain medications (such as cortisone and some used to treat arthritis)

When the bacteria break through, it can cause a recurrence of pneumonia and spread the bacteria to other parts of the body.  The most common body parts to be infected with the TB bacteria (other than the lungs) are the kidneys, lining of the brain, bone, and the spinal cord.

Signs and Symptoms of Tuberculosis

The symptoms of TB infection depend on the part of the body the bacteria have settled.  Signs of pulmonary TB (in the lungs) include:

  • A cough lasting three weeks or longer
  • Pain in the chest
  • Coughing up blood and/or phlegm from deep inside the lungs (sputum)
  • Fatigue or weakness
  • Lack of appetite
  • Weight loss not explained by anything else
  • Fever
  • Chills
  • Night sweats
Symptoms of Tuberculosis; Photo courtesy of Mikael Häggström  Source: Wikimedia CommonsCredit: Photo courtesy of Mikael Häggström Source: Wikimedia Commons

Symptoms don’t necessarily appear right away.  It can take months from the initial contact before symptoms began.  The first signs of pulmonary TB are the fatigue, unexplained weight loss, fever and night sweats.   As it worsens, the other symptoms began to appear.

Treatment for Tuberculosis

Treatment for TB involves a long regime of medication.  It takes six to nine months to treat the disease, depending on whether or not the TB is latent or active.  The exact medication as well as the length of administration is also determined by the person’s overall health, age, possible drug resistance and where the infection is located in the body.[5]

Latent TB may only require one type of drug; however, active tuberculosis requires several drugs to be taken at the same time.[5]  The most common medications used to treat latent TB are:[4]

  • Isoniazid INH
  • Rifampin (RIF)
  • Rifapentine (RPT)

If the tuberculosis bacteria are active, they are then considered TB disease and the U.S. Food and Drug Administration (FDA) has approved ten drugs for treatment.[4]  The core of the medication regime include:[4]

  • Isoniazid (INH)
  • Rifampin (RIF)
  • Ethambutol (EMB)
  • Pyrazinamide (PZA
Invincible Microbe: Tuberculosis and the Never-Ending Search for a Cure
Amazon Price: $18.99 $3.99 Buy Now
(price as of Dec 2, 2015)

All of the medications used to treat TB can be toxic to the liver so monitoring by the treating physician is crucial.  In addition, as with most medication, TB medications do have side effects such as nausea, jaundice and loss of appetite.

It is extremely important to take the full regime of medication even if after a few weeks one feels better.  If the medications are stopped or doses skipped, it can allow the bacteria still alive to develop resistance to the drugs and/or the illness to return.

Who is at Risk for TB?

Although anyone can contract the TB disease, there are some factors which put some people at a higher risk than others.  First and foremost, anyone with an already weakened immune system is at risk for TB.  Other risk factors include living in or traveling to countries with high rates of tuberculosis such as India or Mexico; living in a refugee camp or shelter; working in the health care field; having a lack of  and/or access to medical care; having a substance abuse issue; and using tobacco.[4]

2009 Prevalence of TB Map; Source: Wikimedia CommonsCredit: Source: Wikimedia Commons

In the United States vaccines for tuberculosis is not routinely given.  In other countries where TB is common, the vaccine Bacille Galmettte-Guerin (BCG) is given, though the vaccine is not always effective in protecting against the TB disease.[4]  According to the World Health Organization (WHO), the occurrence of TB is on the decline in most countries, some more slowly than others.[7]  WHO continues to be at the forefront of efforts to eradicate the TB disease across the globe through research, education, funding and hands-on activities.


 The copyright of the article Tuberculosis Still a Major Killer is owned by Cheryl Weldon and permission to republish in print or online must be granted by the author in writing.