CMV infection is considered to be human-specific. Although the age at which symptoms and clinical signs appear and the route of infection differs from person to person, very few people are immune to infection over their lives. CMV is a common human infection, according to serologic studies done across the world. CMV can be discovered in 40 percent to 100 percent of persons, depending on socioeconomic situations and the population studied. As the age of the individual increases, the chances of the individual getting infected with CMV also increases. In some patients with CMV disease and a transplant, age is one of the risk factors of developing CMV.