Prevention
Over the years many efforts have been made to stop the spread of tuberculosis. From legislation banning spitting in public, to the development of vaccinations, to public screening programs, preventative efforts have sought to inform people about the disease and to stop the spread of the disease.
Albert Calmette and Camille Guérin – BCG Vaccine
The first successful vaccine against tuberculosis was developed at the Pasteur Institute by Albert Calmette and Camille Guérin and announced to the medical community in 1921. In the course of their earlier research they had noted that repeated sub-culturing of the TB bacteria reduced its virulence, so they purposefully set out to decrease virulence through sub-culturing to create a vaccine. From 1908 the bacteriologist and veterinarian worked on creating an attenuated, or weakened, strain of Mycobacterium bovis that, when injected into animals, would not cause tuberculosis. After almost fifteen years and 230 transplantations of the bacteria, Calmette and Guérin achieved their goal. By 1921 their tests indicated that they had succeeded in producing a non-virulent strain of the bacteria and human trials began in France, Germany and Canada.
In Montreal, Drs. J. A. Baudoin and Petit conducted studies on the use of BCG in newborns beginning in 1925. In 1934 they found that the vaccine reduced the risk of mortality of at risk children by 4.5 times the unvaccinated group. Their findings showed BCG to be particularly effective for children under one year of age living in a tuberculous household. By 1941 they had vaccinated 44,734 infants, and found that mortality was reduced in 0-1 year olds by 66%. For youth aged 0-15 mortality was reduced by 61%. As a result, Quebec began a program to vaccinate newborns and in 1949 began school vaccination campaigns.
Tests on the effectiveness of BCG were also undertaken by Dr. R. G. Ferguson in Fort Qu’Appelle, Saskatchewan. Working with the Native population conducting tuberculin tests, Ferguson found high rates of TB in the Native community and a mortality rate that was ten times greater than the White community. In light of these observations, Ferguson sought permission to test BCG within the aboriginal population of Fort Qu’Appelle. He began administering the vaccine in 1933. By 1938 preliminary results showed that although the overall mortality rate between vaccinated and unvaccinated groups remained the same, the mortality rate of children in a tuberculous environment decreased by 75%.
Although there was initially mixed reaction to the BCG vaccine, by 1948 subsequent tests, such as those by Baudoin and Ferguson, were convincing the medical community of the benefits of the vaccine to certain communities.
As demonstrated by such medical researchers, the BCG vaccine is especially good at preventing TB infection in children, but has much more variable results (0-80% efficacy) at preventing pulmonary TB in adolescents and adults.
The BCG vaccine continues to be used around the world to prevent TB infection. It is given, for example, to all children under the age of three in South Africa. It is not given in areas of low TB incidence though, because the vaccine decreases the efficacy of tuberculin skin tests; it is uncommon among native-born Canadians and Americans.
Explore the picture gallery to learn more about this preventative measure.
