6 Signs of Tuberculosis (TB) and Tests for Diagnosis

Tuberculosis is a serious health problem globally but uncommon in most developed countries. There has been a steady decline in tuberculosis cases in the United States and the disease causes less than 600 deaths a year. Nevertheless tuberculosis is still a global health concern as the disease can be easily spread and the rise of multi-drug resistant TB means that the disease is becoming more difficult to treat.

How To Spot Tuberculosis

Most people believe that tuberculosis is easily spotted by a persistent cough, especially with coughing up bloody sputum. While this is a characteristic sign of pulmonary tuberculosis (lung TB), the infection can also affect other parts of the body where there may be no cough present. Tuberculosis infections outside of the lung are known as extra-pulmonary TB. It can affect any part of the body including the bone, spine, kidney, brain, eyes, skin and other organs.

However, pulmonary tuberculosis (lung TB) is by far the more common.  The microbe responsible for TB, known as Mycobacterium tuberculosis, is easily spread from an infected person to an uninfected person through droplets during coughing. The microbe can then enter the lung of an uninfected person but may still not cause the disease if a person is healthy and has a strong immune system.

Read more on lung tuberculosis.

Who gets TB?

Tuberculosis is generally associated with a  weakened immune system. Therefore this disease is most commonly seen among people with HIV/AIDS where the virus weakens the immune system. However, the immune system can be weakened through various other ways, from having certain chronic disease like poorly controlled diabetes, to being malnourished and even with prolonged psychological stress.

This means that any person who experiences a drop in immune defenses and is exposed to a person with TB or carries the TB microbe can then develop active tuberculosis. It can be difficult to spot a person with tuberculosis when the typical symptoms of persistent coughing, bloody sputum and weight loss are not present. Other symptoms like fever, chills and night sweats may not be as easy to identify or not seen at all except by close contacts of the infected person.

Globally, 1 in 3 people are infected with tuberculosis. Not all of these infections are active tuberculosis. People living in certain countries may be at a greater risk due to the incidence in these nations. The top five countries with the highest infection rates are China, India, Indonesia, Pakistan and South Africa. Every year tuberculosis claims over 1 million lives across the globe.

What does TB Look Like?

The signs and symptoms of pulmonary tuberculosis (lung TB) has been discussed below since it is the most common. It is important to note that other serious lung infections can also present in a similar manner, as well as lung cancer. Always consult with a medical professional to confirm a diagnosis of tuberculosis. Immediate antibiotic therapy needs to be commenced once a TB diagnosis is confirmed, and treatment must be continued for the prescribed duration (usually 6 months).

Persistent Coughing

A characteristic sign of pulmonary tuberculosis (TB) is a persistent cough that tends to last for more than 3 weeks. This is due to the presence of the TB bacilli in the lung which irritates the lung tissue and triggers a major immune response against it resulting in lung inflammation. The cough gets progressively worse over time and is often associated with chest pain and bloody sputum.

Read more on persistent coughing.

Bloody Sputum

Tuberculosis causes a productive cough, meaning that there is mucus that is expectorated when coughing. This mucus, known as sputum, may initially be blood-streaked and eventually be bloody. It occurs as a result of the inflammation, damage and destruction of the lung and airway tissue. Therefore tuberculosis (TB) should always be suspected when there is a persistent cough with bloody sputum.

Chest Pain

Chest pain is another common feature of pulmonary tuberculosis. It occurs as the lung tissue is destroyed and with persistent coughing that strains the airways as well as the chest wall. Understandably the chest pain tends to worsen after coughing and may also be felt during breathing. In rare cases TB can spread to the heart (cardiac tuberculosis) and this may be the origin of the chest pain.

Unintentional Weight Loss

Unintentional weight loss is another sign of tuberculosis. This is in part due to the loss of appetite that is common in pulmonary tuberculosis. It is further exacerbated by conditions like AIDS which increases the chances of TB. A person can become severely emaciated over time.


Fatigue is a non-specific symptom of tuberculosis. It is present in many different diseases but when fatigue is accompanied by the other signs mentioned above, then pulmonary tuberculosis should be suspected. Eventually a person with TB is extremely debilitated and unable to undertake daily tasks.

Night Sweats

Another characteristic sign of tuberculosis is night sweats. A person may awaken from sleep to find excessive perspiration that does no correlate to the environmental conditions. At times, the perspiration can be excessive enough to soak bed linen.

Other Signs

  • Fever
  • Chills
  • Loss of appetite
  • Lymphadenopathy (enlarged lymph nodes)

Tests for Tuberculosis

A diagnosis of tuberculosis needs to be confirmed with certain investigations. These tests must be done by a medical professional and some tests need to be done in a laboratory. TB tests include:

  • Skin test (tuberculin skin test or Mantoux tuberculin test) where a small amount of the TB protein (antigens) is introduced to the outer layers of the skin over the test site.
  • Blood test (Interferon Gamma Release Assay or IGRA) where a blood sample is mixed with TB protein (antigens) to evaulate if there is a reaction.
  • Sputum test (sputum culture and cytology) where a mucus (sputum) sample is used to grow the microbes within it on a substrate (culture) or where the cells in the sputum are examined under a microsope (cytology).

A chest x-ray may also be done but this alone is not sufficient to diagnose tuberculosis. Instead the findings of an x-ray must be correlated with another test like the TB skin test to confirm a diagnosis of tuberculosis.

Please note that any information or feedback on this website is not intended to replace a consultation with a health care professional and will not constitute a medical diagnosis. By using this website and the comment service you agree to abide by the comment terms and conditions as outlined on this page