Smallpox used to be among the most dreaded diseases in history. It has been known to exist since antiquity. It had a high case fatality of 20 – 40%, i.e. almost 30% of the patients lost their lives. It killed more than 300 million people in the 20th century.
Epidemics occurred throughout the world, especially in India. In India, epidemics occurred every 5 to 7 years, even after the vaccine was brought in. It was known to wipe out entire villages and tribes worldwide and even change the course of history.
Those who survived were left with long term complications like scarred skin, pockmarks on body and blindness (due to corneal scarring). Hence the loss was not only in health sector; it was socially, politically and economically devastating too. This steered the international level efforts for its eradication, through the World Health Organization (WHO).
The eradication program began in 1967 and included widespread vaccination and extensive surveillance. The efforts led to the eradication of this highly fatal and disfiguring disease. The last case was reported from Somalia in 1977. Eradication was declared in 1980, which means that there was no virus in nature.
To avoid any risk of failure of eradication, WHO asked the laboratories around the world to destroy any stocks of smallpox virus maintained for research. In India all the 6 labs complied.
Presently, only two labs maintain smallpox virus stock under supervision of WHO
1. One is in the USA i.e. the Center for Disease Control and Prevention in Atlanta, Georgia
2. Another is in Russia, i.e. the State Research Center of Virology and Biotechnology (VECTOR Institute) in Koltsovo.
No other disease has since been eradicated despite intensive efforts e.g. for Polio
Can smallpox come back and devastate the world?
Even though smallpox and its causative virus (variola) are eradicated from the world, live samples continue to exist in 2 laboratories as mentioned above.
If this virus manages to emerge out of these labs, the resulting devastation could be beyond imagination.
Two phenomena resulted due to eradication, which heighten the dread:
1. Smallpox vaccination was discontinued throughout the world in 1980. People born after 1980 have NO IMMUNITY against the disease.
• Moreover the immunity wanes with time among those who were vaccinated.
• Some stocks of the vaccine do exist but the capacity to manufacture in large quantities is extremely limited currently.
2. Physicians today do not have clinical experience in diagnosis and management of cases of smallpox.
• Large scale trainings may be needed to enable them to diagnose and manage potential cases of smallpox
The virus may leak out of the labs via various mechanisms:
1. Accidental leak:
Although strict safety measures are taken for storing the frozen virus, human error and accidents may be unforeseen. There have been at least 2 such examples.
• The last natural case was reported in 1977 but the true last case was in 1978 which occurred in an employee of a laboratory when the virus leaked out.
o The case was contained effectively and the world moved on to eradication.
• The second example is more recent. An explosion occurred in the Russian lab which houses the smallpox virus samples in 2019.
o The authorities assured the safety of the virus sample.
2. Deliberate leak e.g. use of smallpox as a biological weapon:
There is concern that the virus may fall into the hands of people with wrong intents. The present war in one of the regions housing the virus escalates this concern.
Other diseases caused by poxviruses (related to smallpox) become relevant as immunity of smallpox vanishes.
Other diseases caused by poxviruses have been increasing.
A case in hand is of Monkeypox which is closely related to smallpox has been declared as Global emergency by WHO. This disease is also caused by the poxvirus family k/a Orthopoxvirus.
The two diseases are clinically similar but currently monkeypox is less lethal compared to smallpox: The death rate for monkeypox is 10%, as against 30% for smallpox.
In fact, there is a significant immunity to monkeypox in those vaccinated against smallpox.
Previously monkeypox spread between humans was limited, probably due to herd immunity provided by widespread smallpox vaccination.
However with cessation of smallpox immunization and waning immunity, monkeypox has the potential of:
• Human to human spread
• Being more clinically severe and fatal
• Providing more opportunities for virus mutation.
As on 24th July 2022: Globally, over 16000 cases of monkeypox have been reported from 75 countries. In the WHO South-East Asia Region, four cases of monkeypox have been reported, three from India and one from Thailand.
Despite the similarity of name and some clinical features, it’s important to know that smallpox is not related to chickenpox.
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Smallpox: Why Humanity should not Forget: http://www.ihatepsm.com/blog/smallpox-why-humanity-should-not-forget-dre...