Tuberculosis, once the leading cause of death in the U.S. and elsewhere, remains a threat to public health.
Tuberculosis, or TB, results from a bacterial infection that usually affects the lungs. Symptoms can seem similar to those of the flu or another respiratory infection at first, but if TB is not treated properly, it can be fatal. In fact, according to the national Centers for Disease Control and Prevention (CDC), tuberculosis was once the leading cause of death in the United States, though the number of TB infections has declined since the development of penicillin in the 1940s.
Although penicillin and other antibiotic drugs have decreased the incidence of tuberculosis, the disease has never been eradicated. In 2004, for example, there were more than 14,000 reported cases of TB in the United States, according to the CDC. And TB is much more common in other parts of the world; according to the Mayo Clinic, about one-third of the human population is infected with the bacteria worldwide. With that in mind, it's a good idea to know what tuberculosis symptoms look like.
The symptoms of active TB include:
Active TB is contagious and is transmitted through the air when an infected person coughs or sneezes and another person unwittingly inhales the tuberculosis bacteria. Usually TB is transmitted through long-term contact – through frequent exposure to family members, for example – rather than incidental contact, like passing strangers in a public place.
A TB infection does not lead to the symptoms of active tuberculosis in every case. Often the immune system can fight the bacteria and keep it from growing without fully eliminating it. This condition is called latent TB infection.
Someone with a latent TB infection experiences no symptoms and is not contagious, but the bacteria still remains in the body, biding its time and waiting for an opportunity to take over. An immune system weakened by certain diseases, medical treatment, substance abuse or malnutrition, however, may allow the latent TB infection to become active tuberculosis.
Several tests can determine the presence of active TB or a latent TB infection, including skin tests, blood tests and chest X-rays. Certain people should be tested regularly for TB because of an increased risk of contracting the infection. People who live or work in prisons, nursing homes, hospitals, migrant farm camps and homeless shelters should be tested regularly, as should HIV carriers and intravenous drug users. People who have spent time with those who have active TB should be tested as well.
Active TB is treated with a combination of several powerful drugs, usually for six to 12 months. Even though the symptoms of active TB may disappear fairly quickly, it's necessary to take the medications for the full length of time prescribed. Incomplete treatment can lead to drug-resistant tuberculosis, a far more serious problem that can require up to two years of therapy along with surgical removal of infected tissue.
Many people who have latent TB infections never develop the active form of the disease. But some have a much higher risk of developing active TB than others, and people in these high-risk groups should get preventive treatment to kill the bacteria before it can become active. According to the CDC, people who are especially at risk for active TB include:
People who were not correctly treated for TB in the past.