What is Tuberculosis (TB)
Tuberculosis (TB) is a potentially serious infectious disease that mainly affects your lungs. The bacteria that cause tuberculosis are spread from one person to another through tiny droplets released into the air via coughs and sneezes.
Once rare in developed countries, tuberculosis infections began increasing in 1985, partly because of the emergence of HIV, the virus that causes AIDS. HIV weakens a person’s immune system so it can’t fight the TB germs. In the United States, because of stronger control programs, tuberculosis began to decrease again in 1993, but remains a concern.
Many strains of tuberculosis resist the drugs most used to treat the disease. People with active tuberculosis must take several types of medications for many months to eradicate the infection and prevent development of antibiotic resistance.
Fast Facts on Tuberculosis
Here are some key points about tuberculosis. More detail and supporting information is in the main article.
- In 2012, 1.3 million people were believed to have died because of tuberculosis with an estimated 8.6 million new cases of TB worldwide.13
- The World Health Organization estimates that 9 million people a year get sick with TB, with 3 million of these “missed” by health systems.
- TB is among the top 3 causes of death for women aged 15 to 44.
- Tuberculosis is caused by bacteria (Mycobacterium tuberculosis) that most often affect the lungs, although it can also affect other organs such as the kidneys and heart.5
- TB can either be active or latent (where no symptoms occur, and the condition cannot be passed on).
- TB symptoms (cough, fever, night sweats, weight loss etc.) may be mild for many months, and people ill with TB can infect up to 10-15 other people through close contact over the course of a year.
- TB is an airborne pathogen, meaning that the bacteria that cause TB can spread through the air from person to person.
- People with compromised immune systems are most at risk of developing active TB and dying from the disease; people with HIV are 26-31 times more likely to develop TB.
- Tobacco use has been found to increase the risk of developing active TB with more than 20% of TB cases worldwide attributable to smoking.
- TB bacteria can develop a resistance to antibiotics that fail to kill them completely.
- The most common diagnostic test for tuberculosis is a skin test.
- The majority of TB cases can be cured with antibiotic treatment, with isoniazid and rifampicin the two most powerful, first-line (or standard) anti-TB drugs. TB bacteria can develop a resistance to antibiotics that fail to kill them completely.
- It is vital that any courses of treatment given are fully completed to increase the chance of successful eradication of infection and to reduce the risk of antibiotic resistance developing.
What causes Tuberculosis
TB is caused by a bacterium called Mycobacterium tuberculosis.
TB that affects the lungs is the most contagious type, but it usually only spreads after prolonged exposure to someone with the illness. For example, it often spreads within a family who live in the same house.
In most healthy people, the immune system (the body’s natural defence against infection and illness) kills the bacteria, and you have no symptoms.
Sometimes the immune system cannot kill the bacteria, but manages to prevent it spreading in the body. This means you will not have any symptoms, but the bacteria will remain in your body. This is known as “latent TB”.
If the immune system fails to kill or contain the infection, it can spread within the lungs or other parts of the body and symptoms will develop within a few weeks or months. This is known as “active TB”.
Latent TB could develop into an active TB infection at a later date, particularly if your immune system becomes weakened.
Signs and Symptoms of Tuberculosis
Classic clinical features associated with active pulmonary TB are as follows (elderly individuals with TB may not display typical signs and symptoms):
Chest pain (can also result from tuberculous acute pericarditis)
Symptoms of tuberculous meningitis may include the following:
Headache that has been either intermittent or persistent for 2-3 weeks
Subtle mental status changes that may progress to coma over a period of days to weeks
Low-grade or absent fever
Symptoms of skeletal TB may include the following:
Back pain or stiffness
Lower-extremity paralysis, in as many as half of patients with undiagnosed Pott disease
Tuberculous arthritis, usually involving only 1 joint (most often the hip or knee, followed by the ankle, elbow, wrist, and shoulder)
Symptoms of genitourinary TB may include the following:
In men, a painful scrotal mass, prostatitis, orchitis, or epididymitis
In women, symptoms mimicking pelvic inflammatory disease
Symptoms of gastrointestinal TB are referable to the infected site and may include the following:
Nonhealing ulcers of the mouth or anus
Difficulty swallowing (with esophageal disease)
Abdominal pain mimicking peptic ulcer disease (with gastric or duodenal infection)
Malabsorption (with infection of the small intestine)
Pain, diarrhea, or hematochezia (with infection of the colon)
Physical examination findings associated with TB depend on the organs involved. Patients with pulmonary TB may have the following:
Abnormal breath sounds, especially over the upper lobes or involved areas
Rales or bronchial breath signs, indicating lung consolidation
Signs of extrapulmonary TB differ according to the tissues involved and may include the following:
The absence of any significant physical findings does not exclude active TB. Classic symptoms are often absent in high-risk patients, particularly those who are immunocompromised or elderly.
Who Should Get Tested for Tuberculosis
TB tests are generally not needed for people with a low risk of infection with TB bacteria.
Certain people should be tested for TB bacteria because they are more likely to get TB disease, including:
- People who have spent time with someone who has TB disease
- People with HIV infection or another medical problem that weakens the immune system
- People who have symptoms of TB disease (fever, night sweats, cough, and weight loss)
- People from a country where TB disease is common (most countries in Latin America, the Caribbean, Africa, Asia, Eastern Europe, and Russia)
- People who live or work somewhere in the United States where TB disease is more common (homeless shelters, prison or jails, or some nursing homes)
- People who use illegal drugs
Who is at risk with Tuberculosis?
People with compromised immune systems are most at risk of developing active tuberculosis.
HIV suppresses the immune system, making it harder for the body to control TB bacteria. People who are infected with both HIV and TB are around 20-30% more likely to develop active TB than those who do not have HIV.
Tobacco use has also been found to increase the risk of developing active TB. Over 20% of TB cases worldwide are related to smoking.
How Tuberculosis is Treated
With treatment, TB can usually be cured. Most people will need a course of antibiotics, usually for six months.
Several different antibiotics are used. This is because some forms of TB are resistant to certain antibiotics. If you are infected with a drug-resistant form of TB, treatment with six or more different medications may be needed.
If you are in close contact with someone who has TB, tests may be carried out to see if you are also infected. These can include a chest X-ray, blood tests, and a skin test called the Mantoux test.
The BCG vaccine can provide effective protection against TB in up to 8 out of 10 people who are given it.
Currently, BCG vaccinations are only recommended for groups of people who are at a higher risk of developing TB.
This includes children living in areas with high rates of TB, or those who have close family members from countries with high TB rates, and people under the age of 16 who are going to live and work with local people in an area with high rates of TB for more than three months.
It’s also recommended that some people, such as healthcare workers, are vaccinated because of the increased risk of contracting TB while working.