Chapter 15 Poxvirus infections.

Poxviruses are the largest and most complicated viruses of humans and they more resemble reduced bacteria than viruses. The relatedness and important differentiations between variola, monkeypox and vaccinia have been analyzed at DNA level. The laboratory differentiation between variola, monkeypox, vaccinia, and cowpox is especially important since they can cause similar symptoms. Smallpox has for thousands of years been a most feared disease. It has left its marks on the 3000 year old mummy of Ramses V and it was the deadly cargo of the conquistadore ships landing in Mexico. The successful global vaccination campaign resulted, in 1977, in the last natural case of smallpox. World Health Organization (WHO) has officially declared that smallpox had been completely eradicated from the earth. The smallpox virus is still present in a few freezers in special designated laboratories. The eradication of smallpox will be described at some length as the first, but hopefully not the last, example of an eradication of a severe human disease.