Tuberculosis (also known as "TB") is a disease caused by a type of bacteria called
Mycobacterium tuberculosis. TB mainly infects the lungs, although it can
also affect other organs.
When someone with untreated TB coughs or sneezes, the air is filled with droplets
containing the bacteria. Inhaling these infected droplets is the usual way a person
One of the worst diseases of the 19th century, TB was the eighth leading cause
of death in children 1 to 4 years of age in the 1920s. As the general standard of
living and medical care got better in the United States, the incidence of TB decreased.
By the 1960s, it wasn't even in the top 10 causes of death among kids of any age group.
But TB is making a comeback in the United States today — particularly among
the homeless, those in prison, and people whose immune systems have been weakened
because of HIV infection.
Signs and Symptoms
In older infants and children, the first infection with the tuberculosis bacteria
latent tuberculosis infection (LTBI) usually produces no signs or
symptoms, and a chest X-ray shows no signs of infection. A person with a positive
tuberculin test (PPD), even if they show no disease, will usually
need to receive medication.
A primary infection usually resolves on its own when a child develops immunity
over a 6- to 10-week period. But in some cases, TB can progress and spread all over
the lungs (called progressive tuberculosis) or to other organs. This
causes signs and symptoms like fever, weight loss, fatigue, loss of appetite, and
Another type of infection is called reactivation tuberculosis.
Here, the primary infection has resolved, but the bacteria are dormant,
or hibernating. When conditions become favorable (for instance, a lowered immunity),
the bacteria become active. Tuberculosis in older children and adults may be of this
The most prominent symptom is a persistent fever, with sweating during the night.
Fatigue and weight loss may follow. If the disease progresses and cavities form in
the lungs, the person may experience coughing and the production of saliva, mucus,
or phlegm that may contain blood.
Tuberculosis is contagious when it's airborne and can be inhaled by others.
The incubation period (the time it takes for a person to become infected after being
exposed) varies from weeks to years, depending on the individual and whether the infection
is primary, progressive, or reactivation TB.
Preventing TB depends on:
avoiding contact with those who have the active disease
using medications as a preventive measure in high-risk cases
maintaining good living standards
New cases and potentially contagious patients are identified through proper use
and interpretation of the tuberculin skin test.
A vaccine called BCG (Bacille Calmette-Guérin) is considered controversial because
it isn't very effective in countries with a low incidence of TB, such as the United
States. However, it may be considered for people moving to countries where TB is common.
A doctor may recommend hospitalization for the initial evaluation and treatment
of TB, especially if:
the patient is an infant
there are severe drug reactions
there are other diseases along with TB
However, most people with tuberculosis can be treated as outpatients and cared
for at home. The treatment is usually in the form of oral medications. In some cases,
three or four drugs may be prescribed.
Even though treatment may require months to complete, it's very important that
the full course of medicine be taken in order for tuberculosis to be cured.
Tuberculosis is a chronic disease that can persist for years if it isn't treated.
When to Call the Doctor
Call the doctor if you:
have been in contact with someone who has (or is suspected to have) tuberculosis