Small Pox - Variola

Small Pox - Variola

	Small Pox - Variola It has a complex architecture without obvious symmetry. The virus is a brick shaped DNA particle, largest in size - 270 nm. The nucleocapsid is surrounded by a swirling series of fibers and has no envelope. The particles have rounded corners and a central dense region with crescentic dense areas on each side. The surface layer-is made of threadlike, double ridgedl, beaded structures. in section, there appears a central nucleoid with a dumbbell shaped dense core composed of regularly arranged, DNase sensitive, electron dense threadlike structures.
The nucleoid is surrounded by lipoprotein membranes. Between the nucleoid and the outer viral coat is an ellipsoidal body which causes a prominent central bulging of the virion. The particle is composed of about 3.2% DNA associated with spermidine, 91.6% protein, 5% lipid and 0.2% non-DNA carbohydrate (present in the membrane glycoproteins). The early symptoms are chills, fever and general prostration. With the fall in temperature, pink red spots called macules appear, first on the scalp and fore head, then on neck and extremities and finally on trunk. The spot now turn to pink pimples or papules, and later fluid filled vesicles.
The technical name, variola is derived from the Latin. varus meaning pimple. In the final stage, the vesicles advance to pustules, covering the body surface. When they break open, pus comes out. They are deep in the skin rather than on surface as in chicken pox. The pustules may form a soft crust, which falls of leaving a pitted scar, or pock. The name small pox was used to distinguish the pock from the larger lesions of syphilis or varicella (chicken pox). Transmission is by contact with the skin or any of the body fluids including blood, urine or droplets.
In 1798, an English physician, Edward Jenner observed that milkmaids and others working with dairy cattle contracted a closely related but mild form of pox called cowpox, or vaccinia from the Latin vacca means cow. Apparently those who had recovered from cowpox did not contract small pox. Jenner, therefore, substituted material from a cow pox lesion for the smallpox material and established the process of vaccination. His method became so famous that Napoleon ordered his army to be vaccinated in 1806. Introduction of the cowpox virus to the blood stream induces the body to manufacture antibodies which neutralise both the cowpox and smallpox viruses as they are partially similar.
	The World Health Organisation (WHO) received in 1967 funds for an attempt at global eradication of smallpox. By a process of Surveillance containment, pox patients were isolated, and every, known case was vaccinated. The last epidemic occurred in 1974 in Bangladesh, and in 1976 in Ethiopia. By October 1977, the WHO claimed that the last case had been isolated. On, October 26, 1979 the announcement was made that smallpox had, been eliminated from the earth, the first such claim made for any disease. The virus is said to exist only in four research laboratories of U.S.A., Russia, U.K. and Japan, permitted by the WHO.

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