Tuberculosis (popularly known as "TB") is a disease caused by the bacteria Mycobacterium tuberculosis. It mainly infects the lungs, although it also can 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 gets TB.
One of the most dreaded diseases of the 19th century, TB was the eighth leading cause of death in children 1 to 4 years of age during the 1920s. As the general standard of living and medical care improved in the United States, the incidence of TB decreased. By the 1960s, it wasn't even in the top 10 causes of death among children of any age group.
But TB is making a comeback in the United States today particularly among the homeless, those in prison, and those rendered susceptible because of HIV infection.
Signs and Symptoms
In older infants and children, latent tuberculosis infection (LTBI), which is the first infection with the tuberculosis bacteria, usually produces no signs or symptoms. In addition, a chest X-ray shows no signs of infection.
In most cases, only a tuberculin skin test (used to figure out if someone has been infected by the tuberculosis bacteria) is positive, indicating that the child has been infected. Children with a positive tuberculin test, even if they show no disease, will usually need to receive medication.
This primary infection usually resolves on its own as a child develops immunity over a 6- to 10-week period. But in some cases, it can progress and spread all over the lungs (called progressive tuberculosis) or to other organs. This causes signs and symptoms such as fever, weight loss, fatigue, loss of appetite, and cough.
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, due to lowered immunity), the bacteria become active.
Tuberculosis in older kids and adults may be of this type. 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 might have coughing and the production of saliva, mucus, or phlegm that may contain blood.