Bacillus Calmette Guerin

Excerpt

Bacillus Calmette-Guérin (BCG) is the live attenuated vaccine form of Mycobacterium bovis used to prevent tuberculosis and other mycobacterial infections. The vaccine was developed by Calmette and Guérin and was first administered to human beings in 1921. BCG is the only vaccine against tuberculosis. It is the most widely administered vaccine and usually a part of the routine newborn immunization schedule. BCG vaccine also offers protection against non-tuberculous mycobacterial infections like leprosy and Buruli ulcer. It is also used in the treatment of superficial carcinoma of the bladder.

BCG vaccine is a fairly safe vaccine and it is not associated with severe complications. Prior to the mycobacterial infection, vaccine-induced or acquired naturally can protect against subsequent infection due to mycobacteria including tuberculosis. Prior infection with nontuberculous mycobacteria and Mycobacterium tuberculosis can confer natural protection against tuberculosis infection. Protection against tuberculosis infection is usually due to the immune response to mycobacterial antigens. Prior contained latent infection with Mycobacterium tuberculosis can provide up to 80 percent protection against disease with subsequent exposure. In patients with previous active disease, there is an increased risk of recurrence of active tuberculosis due to distinct strains in both HIV-uninfected and HIV-infected patients. Bacille Calmette-Guérin (BCG) has been associated with a reduction in childhood mortality which is not attributable to tuberculosis. Reduction in childhood mortality may be due to epigenetic reprogramming of the nucleotide-binding oligomerization domain (NOD2) receptor.

BCG vaccine can be given either intracutaneously or intradermally. Research is currently being conducted on respiratory administration since natural infection, and sensitization to Mycobacterium tuberculosis in humans tend to occur in the respiratory system.