The smallpox virus is the cause of the smallpox disease. This disease can cause blindness and can even be fatal. As of 2011 , smallpox viruses are considered to be extinct . However , there are still a few samples of these viruses that are kept in laboratories . This is an example of planned extinction . (a) What questions would you need to take into account while planning for the extinction of bacteria or viruses that cause a fatal disease ? (b) Predict if it is possible to wipe out all harmful bacteria and viruses by planned extinction. Explain your prediction.
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Smallpox is an ancient disease caused by the variola virus. Early symptoms include high fever and fatigue. The virus then produces a characteristic rash, particularly on the face, arms and legs. The resulting spots become filled with clear fluid and later, pus, and then form a crust, which eventually dries up and falls off. Smallpox was fatal in up to 30% of cases. Smallpox has existed for at least 3,000 years and was one of the world’s most feared diseases until it was eradicated by a collaborative global vaccination programme led by the World Health Organization. The last known natural case was in Somalia in 1977. Since then, the only known cases were caused by a laboratory accident in 1978 in Birmingham, England, which killed one person and caused a limited outbreak. Smallpox was officially declared eradicated in 1979. Smallpox no longer occurs naturally since it was totally eradicated by a lengthy and painstaking process, which identified all cases and their contacts and ensured that they were all vaccinated. Until then, smallpox killed many millions of people. The virus which causes smallpox is contagious and spreads through person-to- person contact and saliva droplets in an infected person’s breath. It has an incubation period of between 7 and 17 days after exposure and only becomes infectious once the fever develops.