Tuberculosis primary prevention
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Tuberculosis, or TB is a bacterial infection that kills 3 million people worldwide, more people than any other infection in the world. Approximately one-third of the world is infected, and 15 million people in the US. Active tuberculosis kills 60% of the time if not treated, but treatment cures 90% of patients. Most people are infected with TB have latent TB. This means that the bacteria is controlled by the body's immune system. People with latent TB do not have symptoms and cannot transmit TB to other people. However, later if the infected person has a weakened immune system (AIDS, young children, elderly, sick with other diseases, etc.), the bacteria can break out leading to active TB, or TB disease.
Primary Prevention
Many countries use BCG vaccine as part of their TB control programs, especially for infants. This was the first vaccine for TB and developed at the Pasteur Institute in France between 1905 and 1921.[1] However, mass vaccination with BCG did not start until after World War II.[2] The protective efficacy of BCG for preventing serious forms of TB (e.g. meningitis) in children is greater than 80%; its protective efficacy for preventing pulmonary TB in adolescents and adults is variable, ranging from 0 to 80%.[3]
- Infants or children with negative skin-test results who are continually exposed to untreated or ineffectively treated patients or will be continually exposed to multidrug-resistant TB.
- Healthcare workers considered on an individual basis in settings in which a high percentage of MDR-TB patients has been found, transmission of MDR-TB is likely, and TB control precautions have been implemented and were not successful.
Several new vaccines to prevent TB infection are being developed. The first recombinant tuberculosis vaccine entered clinical trials in the United States in 2004, sponsored by the National Institute of Allergy and Infectious Diseases (NIAID).[5] A 2005 study showed that a DNA TB vaccine given with conventional chemotherapy can accelerate the disappearance of bacteria as well as protect against re-infection in mice; it may take four to five years to be available in humans.[6] A very promising TB vaccine, MVA85A, is currently in phase II trials in South Africa by a group led by Oxford University,[7] and is based on a genetically modified vaccinia virus. Because of the limitations of current vaccines, researchers and policymakers are promoting new economic models of vaccine development including prizes, tax incentives and advance market commitments.[8][9]
References
- ↑ Bonah C (2005). "The 'experimental stable' of the BCG vaccine: safety, efficacy, proof, and standards, 1921–1933". Stud Hist Philos Biol Biomed Sci. 36 (4): 696–721. PMID 16337557.
- ↑ Comstock G (1994). "The International Tuberculosis Campaign: a pioneering venture in mass vaccination and research". Clin Infect Dis. 19 (3): 528–40. PMID 7811874.
- ↑ Bannon M (1999). "BCG and tuberculosis". Arch Dis Child. 80 (1): 80–3. PMID 10325767.
- ↑ WHO/UNICEF Review of National Immunization Coverage 1980–2005: South Africa (PDF). World Health Organization (August 2006). Retrieved on 2007-06-08.
- ↑ National Institute of Allergy and Infectious Diseases (NIAID).First U.S. Tuberculosis Vaccine Trial in 60 Years Begins. National Institutes of Health News 26 January 2004. Retrieved on 19 October 2007.
- ↑ Ha S, Jeon B, Youn J, Kim S, Cho S, Sung Y (2005). "Protective effect of DNA vaccine during chemotherapy on reactivation and reinfection of Mycobacterium tuberculosis". Gene Ther. 12 (7): 634–8. PMID 15690060.
- ↑ Ibanga H, Brookes R, Hill P, Owiafe P, Fletcher H, Lienhardt C, Hill A, Adegbola R, McShane H (2006). "Early clinical trials with a new tuberculosis vaccine, MVA85A, in tuberculosis-endemic countries: issues in study design". Lancet Infect Dis. 6 (8): 522–8. PMID 16870530.
- ↑ Webber, David and Kremer, Michael. Stimulating Industrial R&D for Neglected Infectious Diseases: Economic Perspectives (PDF). Bulletin of the World Health Organization 79(8), 2001, pp. 693–801.
- ↑ Barder, Owen; Kremer, Michael; Williams, Heidi. "Advance Market Commitments: A Policy to Stimulate Investment in Vaccines for Neglected Diseases," The Economists' Voice, Vol. 3 (2006) Issue 3.