Smallpox is the only disease that has been eradicated through the use of vaccination. The mode of transmission was person to person via respiratory droplets that contain the viral particles and the disease was not very contagious. The virus is of low infectivity and transmitted by direct personal contact or indirect contact through towels. Treatment is surgical removal to prevent transmission to other body sites or other people. HSV I is usually transmitted orally and HSV-II genitally.
Herpes viruses gain entrance into the body through mucous membranes or skin.
HSV infections, characterized by vesicles on the skin or membrane, result in multinuclear cells that occasionally contain intracellular Cowdry type A inclusions. The HSV may become dormant after the primary infection by ascending to the corresponding sensory ganglia through the sensory nerves. HSV I neonatal herpes is usually acquired from immediate family members with the disease. Congenital varicella, may be acquired in the first trimester of pregnancy from a mother with varicella. Congenital varicella may cause growth retardation and a range of other neurological defects.