Tuberculosis
Tuberculosis (TB) is a bacterial infection. Although it primarily affects the lungs, it can attack other parts of the body, including the kidneys, spine, brain and bones. There are two classifications of tuberculosis: latent and active. People with latent TB are asymptomatic and not contagious. They are, however, in danger of developing active TB. Those infected with active TB develop symptoms, and are in danger of infecting others. Although the number of reported cases of tuberculosis in the United States has declined annually over the years, it is still a serious problem in other parts of the world.
Causes of Tuberculosis
Tuberculosis is caused by an airborne bacterium known as Mycobacterium tuberculosis. The bacterium spreads when an infected person sneezes, coughs, talks or laughs. What makes TB different from most other infections is that, in the majority of cases, it can remain dormant for years. Those infected may not suffer symptoms until the disease becomes activated. This happen if, or when, the patient's immune system becomes weakened.
Risks for Tuberculosis
Although tuberculosis is contagious, it is not easily transmissible. It is rarely spread among strangers, and usually only contracted after prolonged exposure, in a home or workplace, to a person in whom TB is active. Once those with TB have been treated for at least 2 weeks, they are no longer contagious. Although TB symptoms can develop within weeks of being exposed, in some cases it takes years.
People are at greater risk of contracting tuberculosis if they have compromised immune systems caused by the following:
- Advanced age
- Malnutrition
- Diabetes or other chronic illness
- Chemotherapy treatment
- HIV/AIDS
- Alcoholism or drug abuse
- Use of anti-rejection medications
Because TB is considerably more prevalent in countries with significant poverty and poor sanitation, anyone living in or traveling to such countries is at higher risk of developing the disease.
Symptoms of Tuberculosis
An active tuberculosis infection causes symptoms, and becomes contagious 2 to 8 weeks after infection. A cough that lasts longer than 3 weeks is the most common symptom; others include the following:
- Unintentional weight loss
- Chest pain
- Loss of appetite
- Coughing up of blood
- Fatigue
- Fever
- Chills
- Night sweats
- Shortness of breath
Infected patients can also have more far-reaching symptoms because TB affects other parts of the body. Symptoms vary according to the part of the body that is affected: Tuberculosis of the kidneys, for example, can cause blood in the urine, and tuberculosis of the spine can cause back pain.
Diagnosis of Tuberculosis
To diagnose TB, a physician performs a thorough physical examination, paying special attention to whether the patient has any enlarged lymph nodes. In addition, if TB is suspected, a number of diagnostic tests, including the following, are performed:
- Tuberculin skin test, called the Mantoux test
- Chest X-ray of CT scan
- Blood test
- Sputum examination
- Urinalysis
While the Mantoux test can detect TB even before symptoms appear, it is not entirely reliable, and can provide false positive or false negative responses in a number of situations.
Treatment of Tuberculosis
Tuberculosis is typically treated with antibiotics on a long-term basis, usually for 6 to 12 months. Patients with latent TB may be administered medication to keep their infections from becoming active. Because antibiotics have been used to combat TB for more than half a century, some TB germs have become resistant to antibiotics commonly used to treat the disease. New antibiotics have been developed to use on patients for whom the older antibiotics are not working. Because TB has a tendency to reside in the body for long periods, it is important that a TB patient be checked regularly, and that antibiotic treatment be completed.