New investment, interventions needed to eliminate TB
Laith Abu-Raddad, PhD, Principal Investigator, Director of the Biostatistics and Biomathematics Research Core & Assistant Professor in Public Health
Ghina Mumtaz, MSc, Research Specialist/Epidemiologist
Hiam Chemaitelly, MSc, Research Specialist/Epidemiologist
The authors are members of the Infectious Disease Epidemiology Research Group at WCMC–Q
March 24th is World Tuberculosis Day, a designation by the World Health Organization designed to focus attention on the disease and efforts to eliminate it.
TB Affects One-Third of World’s Population
Tuberculosis (TB) is a common, often deadly infectious disease that affects about one third of the world’s population. It is caused by a specific kind of bacteria and the infection is spread through the air when people cough, sneeze or spit. TB usually attacks the lungs but it can also affect other parts of the body. Symptoms include a chronic cough with blood-tinged sputum, fever, night sweats, and weight loss. However, the disease is latent in most infected people, that is, they don’t suffer from any symptoms. TB becomes active and shows symptoms in about one in twenty of those infected. In those cases, if left untreated, it kills more than half its victims.
Number of New Cases on the Rise
New infections occur at a rate of about one per second. While the proportion of people who become sick with tuberculosis each year is stable or falling worldwide, the absolute number of new cases is increasing because of population growth. In 2007 (the most recent year for which data are available), there were an estimated 13.7 million chronic active cases, 9.3 million new cases, and 1.8 million deaths, mostly in developing countries. In 2007, in the Middle East and North Africa, there were an estimated 770 thousand chronic active cases, 583 thousand new cases, and 105 thousand deaths. The HIV/AIDS pandemic has enlarged the problem, particularly in sub-Saharan Africa where most HIV cases are concentrated, because people with HIV/AIDS are more susceptible to TB.
The Bill and Melinda Gates Foundation (BMGF) in the United States has embarked on a large scale effort to rectify this problem by allocating $900 million for the development of new diagnostics, drugs, and vaccines. The foundation also provided funding for a study to determine the impact of these new products. That study, directed by Laith Abu Raddad, PhD, in collaboration with researchers from Fred Hutchinson Cancer Research Center, the University of Washington, and the World health Organization, was published in the Proceedings of the National Academy of Sciences.* We found that each of the novel vaccines, drug regimens and diagnostics under development will offer substantial reductions in TB incidence and TB-related mortality compared with current approaches.
However, our study also determined that these interventions alone are unlikely to achieve TB elimination by 2050. Elimination will require strategies such as campaigns to identify active cases and the development of new products that target the large pool of TB latent infection carriers worldwide.
*Abu-Raddad LJ, Sabatelli L, Achterberg JT, Sugimoto JD, Longini IM, Jr., Dye C, Halloran ME. Epidemiological benefits of more-effective tuberculosis vaccines, drugs, and diagnostics. Proc Natl Acad Sci U S A 2009,106:13980-13985.