Tuberculosis is a bacterial infection that can pass through the air between people. When it affects the lungs, the medical name for this is pulmonary tuberculosis. It can cause chest pain, severe coughing, and a range of other symptoms.
Tuberculosis (TB) bacteria mainly grow in the lungs, but they can infect other parts of the body. Miliary TB is an advanced form of the disease that develops when the bacteria spread through the bloodstream to infect organs beyond the lungs.
In this article, we look into the symptoms, causes, and treatment of pulmonary TB. We also describe the outlook and when to see a doctor.
Symptoms of TB can develop slowly and may vary. The main symptoms of pulmonary TB include:
- a bad cough that lasts for at least 3 weeks
- chest pain
- coughing up blood or phlegm from the lungs
More general symptoms of TB can include:
People with latent TB do not have any symptoms or feel sick.
TB is an infection caused by a type of bacteria called Mycobacterium tuberculosis (M. tuberculosis).
About one-third of the world's population is infected with this type of bacteria. However, only around 10–20 percent of people with this infection develop "active TB."
A person who carries the bacteria but does not develop symptoms has "latent TB." This is not contagious, but it can eventually develop into active TB, particularly if a person's immune system becomes weakened from a condition such as HIV.
TB can become active when the immune system is unable to prevent the bacteria from multiplying. However, many people with latent TB never go on to develop active disease. A doctor can use a skin or blood test to check for the presence of M. tuberculosis.
People with active pulmonary TB exhale the bacteria in tiny water droplets when they cough, sneeze, or speak. These droplets travel through the air and a person can breathe them in.
However, an individual generally needs to be in prolonged close contact with someone who has active TB to contract the infection. A TB infection in a part of the body other than the lungs is not usually contagious.
A TB vaccine called bacillus Calmette-Guérin (BCG) is available, but it is not in wide use in the United States, where TB rates are low. However, doctors may recommend the vaccine for children or healthcare workers who have a high risk of TB exposure.
Treatment depends on whether a person has active or latent TB.
People with active TB usually need to take a combination of antibiotics for 6–12 months. First-line treatment options include isoniazid, rifampin, ethambutol, and pyrazinamide.
While some people with active TB require a short hospital stay, many can receive treatment at home.
Most people start feeling better and are no longer able to pass on the infection after a few weeks of treatment.
However, it is essential to complete the full course of treatment exactly as the doctor directs to keep the disease from recurring and to prevent the bacteria from becoming resistant to the drugs. Drug-resistant TB is much more difficult to treat and can be very dangerous if a person passes it on to other people.
TB is curable, but it can be life-threatening if a person does not receive the right treatment. Also, latent TB can progress to active TB if a person does not receive preventive treatment.
A doctor can determine whether a person is infected with TB bacteria using a skin or blood test.
The skin test involves a healthcare provider injecting a small amount of fluid called tuberculin into the person's lower arm. The test is positive if the skin develops a bump or swelling within 48–72 hours of the injection.
The blood test involves taking a small sample of blood and analyzing it for an immune system response to the TB bacteria.
If a person tests positive for the bacteria, the doctor may also order a chest X-ray or sputum test to determine whether the infection has progressed to active disease.
Anyone with symptoms of TB should see a doctor for testing. Also, anyone who believes that they may have been in close contact with a person who has active TB should seek medical advice.
According to the Centers for Disease Control and Prevention (CDC), TB is one of the world's deadliest diseases, with approximately 1.3 million related deaths occurring worldwide in 2017. TB is also a leading cause of death among people who have HIV.
However, the CDC report that the incidence of TB in the U.S. has been steadily declining since 1993. The incidence of TB in 2018 was 2.8 cases per 100,000 persons, which is the lowest ever to be reported in the country.
The CDC estimate that up to 13 million people in the U.S. may have latent TB and that around 1 in 10 of these individuals will develop active TB.
The risk of latent TB progressing to active TB is greater among people with weakened immune systems, including those who have HIV or who are receiving immunosuppressive therapy, such as for cancer or an organ transplant.
It is crucial that people seek medical attention if they experience symptoms of TB or have had contact with anyone who has active TB. The disease is highly treatable, especially when a person receives an early diagnosis.
Pulmonary TB is a bacterial infection of the lungs that can cause a range of symptoms, including chest pain, breathlessness, and severe coughing. Pulmonary TB can be life-threatening if a person does not receive treatment.
People with active TB can spread the bacteria through the air. However, a person usually needs to be in prolonged close contact to become infected.
Most individuals who become infected with TB bacteria do not feel sick or experience any symptoms. Doctors describe this as having latent TB. Latent TB is not contagious but it can eventually develop into active TB.
Doctors treat latent or active TB with a long course of antibiotics. People with active TB usually begin to feel better after a few weeks of treatment.