Every year on March 24, the Stop TB Partnership encourages us to observe World TB Day, a day designed to raise awareness and knowledge of the disease responsible for the deaths of several million people annually. On this date in 1882, Dr. Robert Koch announced his discovery of the bacterium that causes tuberculosis: Mycobacterium Tuberculosis. At the time, tuberculosis was ravaging across Europe and the Americas, killing one out of every seven people.
Although great strides in the cure and control of this deadly disease have been made, tuberculosis continues to be the second greatest killer worldwide from an infectious agent, behind HIV/AIDS. One-third of the world’s population is infected with TB, and 95 percent of deaths occur in low- and middle-income countries. TB has been described as a disease of poverty, as overcrowding, unsanitary living conditions, and poor access to health care help the disease spread rapidly. Therefore, the urban poor, refugees, and the homeless are at a particularly high risk of contacting tuberculosis.
Most TB cases are latent. These individuals do not feel sick and show no symptoms, nor can they spread the infection to others. The only two methods to identify latent TB are through a tuberculin skin test or a TB blood test. These are not always available in resource-limited countries. Without treatment, 5-10 percent of infected persons will develop active TB disease. An individual infected with active tuberculosis is estimated to transmit the disease to 10- 15 people within one year, and unfortunately, without proper treatment two-thirds of these patients will die
In 2010, 8.8 million people were infected with TB, 1.45 million of whom died. The highest rates of infection and mortality were found in South East Asia and Africa. Approximately 60 percent of new cases globally were in Asia, while Sub-Saharan Africa had the highest incidence in the world, at 270 new cases per 100,000 people. At greatest risk are children under 3 years of age, and those who suffer from severe malnutrition and are immunocompromised.
Of particular importance is the growing number of multi-drug resistant TB (MDR-TB) cases. This type of infection does not respond to standard first-line drugs and is transmissible from person to person. Patients infected with this type of TB depend on highly toxic and expensive second-line drugs that require far longer treatment regimens and may cause very unpleasant side effects. Resource poor settings are at an incredible disadvantage in regards to both regular and MDR tuberculosis, since rapid diagnostic tools and expensive pharmaceuticals are critical in impeding the spread of this extremely infectious disease.
MDR-TB develops in patients who fail to complete their full course of treatment for regular TB. Failure to complete treatment may be the result of an interruption in drug supply, a choice to stop taking treatment due to side effects, or lack of monetary funds, for example. Prescriptions for poor-quality medicine or the wrong dosage may also cause regular, or drug susceptible, tuberculosis to progress to MDR-TB.
So far, scientists have developed a limited number of tuberculosis drugs, so the increasing numbers of multidrug resistant and extremely drug resistant cases of tuberculosis are a cause for concern. Healthmap recently reported on an alleged case of totally drug resistant TB in Mumbai, which Indian authorities promptly denied. The case was an example of extremely drug resistant TB. Nevertheless, the possibility that a form of TB for which no drugs exist may arise requires immediate attention. Increased efforts in prevention strategies, as well as further research into TB vaccinations are necessary to improving outcomes within those countries that carry the greatest burden.
Over the past several decades, the US has reduced the number of TB infections to impressive levels. In 2011, TB cases in the United States were at an all-time low since reporting began in 1953. There were 10,521 reported cases, or 3.4 cases per 100,000 people, four of which were MDR-TB. However, this number is 12 times higher among foreign-born people. Individuals from Mexico, the Philippines, Vietnam, India, and China were most often infected. A recent report released by the CDC stated: “addressing the increasing difference between TB rates in foreign-born and U.S.-born persons is critical for TB elimination.”
Tuberculosis is spread by bacteria through the air, from person-to-person. Most cases occur within the lungs, but may also affect the brain, kidneys, or spine. Tuberculosis is characterized by a cough (sometimes with sputum or blood), chest pains, weakness, weight loss, as well as fever and night sweats. TB is both treatable and curable, however, as mentioned, if drug regimens are interrupted MDR-TB may develop. This form is far more difficult to treat. The ability to manage TB infection is crucial to controlling the epidemic. Managing TB relies not just on a person’s willingness to comply with drug regimens, but also the socio-economic environment and the resources available to the community.