Tuberculosis (TB), a disease that was once thought to be contained, has reemerged with a drug-resistant strain, and researchers are working hard to find a vaccine that will control its spread. Statistics indicate that one third of the world’s population, approximately 2 billion people, are infected with TB; 90% of those infected do not show symptoms; and generally, TB is curable. In a healthy human body, the immune system is able to react and thwart the Mycobacterium tuberculosis bacteria, keeping the disease from gaining entry. However, if the immune system of the host is already compromised due to AIDS, depression, etc, the body may be unable to fight off the bacteria. The number of cases of TB diagnosed in the United States had risen to 13,779 in 2006. In the 1950s antibiotic drugs were developed which cured TB patients completely, and, as a result of this success, doctors were no longer trained to recognize the symptoms of this disease. Today, diagnosis is still made using the TB skin test, and at the present time there is no vaccine for TB. Although the disease is generally curable, some strains of bacteria have mutated and become drug resistant. MDR (multidrug resistant) and XDR (extremely drug resistant) cases are difficult to diagnose and treat. Unfortunately, most patients with XDR have no chance of recovery. The disease is airborne and can be transmitted from person to person with a cough. The bacteria is inhaled, and the body’s macrophages are activated to ingest the bacteria. In some way, however, the bacteria are able to stop their own “digestion,” multiply inside the macrophages, and break free. The second line of host defense, T cells, is then activated, and these cells release cytokines to kill the bacteria. In a healthy person, the bacteria are killed and the infection is stopped. Occasionally, a cell will escape and remain dormant until another event weakens the host immune system. As a result, patients may develop TB decades after the original infection was present. The research process to combat this disease now centers on how to inactivate the TB bacteria through molecular pharmaceutics, and how best to deliver it to patients. Since the disease is inhaled, work is progressing on a way to deliver the drug directly to the lungs, similar to an asthma inhaler.
(Source: Endeavors, University of North Carolina, fall, 2008)
