62 - Small Pox

*Small is an acute infectious disease caused by VARIOLA VIRUS and clinically characterized by a sudden onset of fever, headache, backache, vomiting and sometimes convulsions, especially in children.

*On the third day of fever, a typical rash appears which is centrifugal in distribution and passes through successive stages of macule, papule, vesicle, pustule and scab with subsequent scarring.

*IMPORTANT DATES ASSOCIATED WITH SMALL POX :
- May 17, 1975 = The last indigenous case of small pox occured in India (Bihar).
- May 24, 1975 = India's last known case of small pox, an importation from Bangladesh occured.
- July 5, 1975 = India was proclaimed as no longer to be small pox endemic.
- April, 1977 = India was declared small pox free by INTERNATIONAL COMMISSION FOR ASSESSMENT OF SMALLPOX ERADICATION.
- October 26, 1977 = World's last case of Small pox occured in Somalia.
- 1978 - Lab accident results in small pox.
- May 8, 1980 = WHO declared that small pox has been eradicated completely.

*Epidemiological factors which have led to the eradication of small pox - these could form the basis for the eradication of other similar diseases :
1. No long-term carrier of the virus
2. No known animal reservoir
3. Life-long immunity after recovery from the disease
4. The detection of cases comparatively simple because the rash was so characteristic and occured in visible parts of the body
5. Persons with sub-clinical infection didnot transmit the disease
6. Vaccine is highly effective; easily administered, heat stable and confers long-term protection.
7. International co-operation.

*As small pox is now eradicated it is often asked, why keep the causative agent and take the risk of laboratory-associated infection? The answer lies in the fact that there exists, in various parts of the world, a number of poxviruses (eg: monkeypox, cowpox, camelpox, tanapox, tateropox) that closely resemble smallpox viurs and can producehuman infections. Other new pox viruses may yet be discovered . The natural histories of these viruses have not yet been delineated, and it is not known whether these agents can someday replace the eradicated smallpox virus. It is necessary to conduct comparative studies on these animal poxviruses.

*To protect from future attacks, vaccine stocks and bifurcated needles for vaccination of about 300 million people are maintained indefinitely by WHO in Geneva, Toronto and New Delhi.