General Virology and DNA Viruses
Which of the following statements describes a characteristic that enabled the worldwide eradication of smallpox in 1980? (AIIMS Nov 2009)
|A||The inactivated smallpox vaccine is easily prepared and safe.|
|B||Smallpox has no known reservoir outside of humans.|
|C||Mass vaccination of the world was possible as a result of easy administration of the vaccine in the field.|
|D||Subclinical smallpox infections were also inhibited through worldwide mass vaccinations.|
a. Smallpox has no known reservoir outside of humans, which was one of the factors which enabled its eradication; answers A, C, D are all incorrect: the vaccination for smallpox consists of a live vaccinia virus and does not contain smallpox virus; mass vaccination of the world was not performed or required because there are no known nonhuman reservoirs of smallpox and subclinical infections do not occur.
b. Thus, large numbers of vaccinations occurring in many populations, such as in the United States, along with strict epidemiologic reporting of smallpox cases worldwide allowed for immunization of those exposed and the elimination of smallpox disease.