Variola virus, the cause of smallpox, TEM

Variola virus, the cause of smallpox (DNA virus, Family Poxviridae), coloured transmission electron micrograph (TEM). Smallpox virus, also known as Variola virus, is highly infectious. Smallpox is caused by either of two virus variants; Variola major and Variola minor. V. major, the deadlier form, has a mortality rate of 25-35%. The virus characteristically causes a severe skin rash, high fever and often death. The attack on skin cells causes the characteristic pimples and pustules associated with the disease. Smallpox is transmitted primarily through social contact or direct contact with infected body fluids or contaminated objects. Edward Jenner produced the smallpox vaccine using cowpox fluid. The practice of vaccination against smallpox spread quickly in Europe and then to North America. The last case of wild smallpox occurred on October 26, 1977. Magnification: x19,815 when shortest axis printed at 25 millimetres. Original image courtesy of the CDC.