What Is Tuberculosis (TB)?
Tuberculosis caused 1.5 million deaths in 2013 alone. Learn the symptoms and treatment of one of the deadliest, most contagious diseases in the world.
Sanaz Majd, MD
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What Is Tuberculosis (TB)?
If you’ve been watching the news closely, you may have heard a little something about the high rates of tuberculosis (TB) infection around the world. Unfortunately, this news was likely trumped by the recent Ebola coverage. But don’t let that fool you. TB is actually a much bigger infectious disease than Ebola.
See also: Should You Worry About the Ebola Outbreak?
The World Health Organization (WHO) just released its 2014 Global Tuberculosis Report. It reported over 9 million cases of active TB in 2013 alone. The infection caused 1.5 million deaths that year. These numbers make TB one of the deadliest contagious diseases ever. Compare that to Ebola‘s 5,000 deaths and you get a very different perspective.
We all need to be aware of TB, as it is one of the most contagious diseases that we know of, and one with some very grave consequences if left untreated. I have seen a few cases of active TB in my Southern California practice recently, so I think it’s crucial for everyone to be aware of what TB is, what symptoms it produces, and how it’s spread and treated.
What Is Tuberculosis (TB)?
TB is caused by the bacteria Mycobacterium tuberculosis. It often affects the lungs of those with an active infection and is spread through the air via air droplets when infected people cough or sneeze into the air.
Once this infected air droplet is inhaled, the bacteria is held captive in our bodies and becomes what we call “dormant” – that is, it literally sleeps and is referred to as “latent TB.” Latent TB is considered quite common – in fact, up to one third of people in the world are said to have latent TB (yep, one third!). Those with latent TB do not feel sick and cannot spread the infection to others. In fact, those with latent TB often don’t even know they have it until they undergo routine screening.
The more spooky part, however, is that in 5-10% of patients with latent TB, at some point the bacteria reactivates and causes potentially nasty symptoms – this is called “active TB.” Even scarier, those with active TB can spread the infection easily to anyone they come into contact with.
Who Gets TB?
Like the common cold or flu virus, anyone can catch TB as long as they are exposed to someone with an active infection who spreads it through the air (via coughing or sneezing). However, certain populations are deemed higher risk of contracting TB. They are:
- The elderly
- People with HIV
- People who suffer from malnutrition
- People taking drugs that suppress the immune system (as in the treatment of Lupus, severe Psoriasis, or Rheumatoid Arthritis)
- Chronic corticosteroid users
- Chemotherapy patients
- People with Diabetes
Symptoms of Active TB
Again, latent TB displays no symptoms. But for active TB, symptoms can be rather vague and mild for some patients, which can make TB difficult to diagnose in areas of the world with a lower incidence, such as the United States. However, anyone with the following symptoms, especially if persistent and/or accompanied by any of the TB risk factors I outlined earlier, should be considered for TB screening:
- Fever (can be either low grade or high and can be transient and not chronic)
- Persistent cough
- Coughing up of blood
- Night sweats
- Unintentional weight loss
- Fatigue
Diagnosis of TB
Those diagnosed with latent TB often discover their carrier status via two possible ways:
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A skin test called a PPD (stands for Purified Protein Derivative). You’ve probably had this test at some point in your life. A small piece of the TB bacteria protein is injected underneath the skin surface of the forearm. Those who have been previously exposed to TB (with latent TB) will form a swelling/red reaction at the site of the injection (from the immune system attacking that piece of protein that it’s seen before).
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A blood test
Active TB is often confirmed with a chest x-ray and/or culture testing done on the sputum (phlegm) produced in patients with suspected TB or a persistent cough.
Treatment of TB
For those with latent TB, the drug called “Isoniazid” (INH) is first-line and can reduce the risk of reactivation of TB later in life by 60-90%. The better you are at taking the drug exactly as prescribed, the more effective it is. However, it’s a drug that needs to be taken once daily for typically 9 months and like other medications, is not without risk. Potential side effects are:
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Liver toxicity: The risk of liver injury is low (1 in 1000), however, and further diminished by avoiding alcohol and Tylenol during the length of treatment. Your doctor may need to monitor you for signs of liver toxicity on a monthly basis throughout the treatment. These signs include: diminished appetite, jaundice, severe fatigue, nausea or vomiting, dark urine, rash, tingling or numbness of hands or feet, fever, abdominal pain, easy bruising or bleeding, and generalized weakness.
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Peripheral neuropathy: This occurs in about 2% of those taking INH and typically starts with tingling or numbness sensations in the hands or feet. It’s greatly reduced if Isoniazid is taken with 25 to 50 mg a day of Vitamin B6.
For those with active TB, treatment often includes a combination of drugs and isolation until the patient produces normal sputum cultures that turn out negative for TB.
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Please note that all content here is strictly for informational purposes only. This content does not substitute any medical advice, and does not replace any medical judgment or reasoning by your own personal health provider. Please always seek a licensed physician in your area regarding all health related questions and issues.
Doctor examining x-ray image courtesy of Shutterstock.
