Tuberculosis, or TB, is caused by the pathogen Mycobacterium tuberculosis. The airborne germs are spread by coughing and sneezing. The immune system may fight off infection or wall off bacteria to keep it dormant, sometimes for years. In active infection,TB forms cavities in the lungs and spreads, sometimes to other areas of the body. Night sweats, coughing, fever and weight loss are symptoms of active tuberculosis. Although the Centers for Disease Control and Prevention (CDC) reports cases in the United States are declining, there are several things that cause the spread of tuberculosis.
Impaired Immune System
Dormant, or latent, TB is not contagious but could become active in time. A healthy person may not develop the disease, but persons with compromised immune function and impaired healing ability—such as transplant patients, diabetics, or those undergoing chemotherapy—have little resistance to exposure. According to the CDC, TB is the worldwide leading cause of death among HIV-infected people. Treatment is made more complex because of drug interactions between HIV and TB medications.
Failed Treatment
When treatment is not properly administered or stops too soon, the germs that cause TB can become resistant to ordinary medications. Multidrug resistant (MDR) strains of tuberculosis are now emerging and pose a greater threat of dying, especially for those co-infected with HIV. Treatment of MDR TB is complex, expensive, and long-term. Public health officials have adopted strategies such as directly observed treatment (DOT) to ensure compliance. This means that, in many cases, public health nurses make daily visits to the homes of persons under treatment and observe that medications are taken correctly. According to the New York City Department of Health, treatment for latent tuberculosis may last nine months and treatment for active tuberculosis takes at least six months. The most common medication used to treat latent TB is isoniazid, or INH. Drug Information Online reports that active TB requires a drug combination, usually at least four medications, to cure the infection. Once treatment has been underway a short time, patients are no longer contagious.
Crowded Conditions and Immigration
The CDC reports that one third of the world's population is infected with TB. Because tuberculosis is airborne, transmission may be rapid among people living in crowded conditions, such as homeless shelters, hospitals and prisons. In the prison population MDR TB is of concern, affecting inmates, staff, and the community that prisoners are released into. In a study published in the May-June 2001 issue of "Public Health Reports," The Federal Bureau of Prisons implemented mandatory chest x-rays for inmates entering a federal detention center in San Diego. Foreign-born inmates accounted for 60 percent of newly diagnosed cases. Researchers concluded that chest x-ray has merit as a rapid-screening device, and its use in prisons provides opportunity to treat high-risk populations that otherwise might elude public health efforts.
