From Wikipedia: Tetralogy of Fallot (TOF) is a congenital heart defect which is classically understood to involve four anatomical abnormalities (although only three of them are always present). It is the most common cyanotic heart defect, representing 55-70%, and the most common cause of blue baby syndrome..
Variola (the virus that causes smallpox) is a member of the orthopoxvirus genus, which also includes viruses that cause cowpox, monkeypox, orf, and molluscum contagiosum. Poxviruses are the largest animal viruses, visible with a light microscope.They are larger than some bacteria and contain double-stranded DNA. Poxviruses are the only viruses that do not need a cell's nucleus to replicate inside the cell. The variola virus is the only known cause of smallpox.The disease affects only humans.oxviruses are the only viruses that do not need a cell's nucleus to replicate inside the cell. The variola virus is the only known cause of smallpox. The disease affects only humans.
1 Smallpox: Smallpox is a serious, contagious, and sometimes fatal infectious disease caused by the variola virus. 2  Historically, smallpox had a mortality rate of as much as 30 percent. 3  In the Americas, it killed as much as 90 percent of the indigenous population after contact with Europeans introduced the disease. Smallpox: Smallpox is a serious, contagious, and sometimes fatal infectious disease caused by the variola virus. 2  Historically, smallpox had a mortality rate of as much as 30 percent. 3  In the Americas, it killed as much as 90 percent of the indigenous population after contact with Europeans introduced the disease.