In such countries it is one of the classic diseases of childhood, with most cases occurring in children up to age 15;  most people become infected before adulthood, and 10% of young adults remain susceptible. In the United States, a temperate country, the Centers for Disease Control and Prevention (CDC) do not require state health departments to report infections of chickenpox, and only 31 states volunteered this information as of 2013. A 2013 study conducted by the social media disease surveillance tool called Sickweather used anecdotal reports of chickenpox infections on social media systems Facebook and Twitter  to measure and rank states with the most infections per capita, with Maryland, Tennessee and Illinois in the top three.In the tropics, chickenpox often occurs in older people and may cause more serious disease. In adults, the pock marks are darker and the scars more prominent than in children. Society and culture
Etymology
How the term chickenpox originated is not clear but it may be due to it being a relatively mild disease. It has been said to be derived from chickpeas, based on resemblance of the vesicles to chickpeas, or to come from the rash resembling chicken pecks. Other suggestions include the designation chicken for a child (i.e., literally child pox), a corruption of itching-pox, or the idea that the disease may have originated in chickens. Samuel Johnson explained the designation as "from its being of no very great danger".
Intentional exposure
Because chickenpox is usually more severe in adults than it is in children, some parents deliberately expose their children to the virus, for example by taking them to "chickenpox parties". Doctors say that children are safer getting the vaccine, which is a weakened form of the virus, than getting the disease, which can be fatal or lead to shingles later in life. Repeated exposure to chickenpox may protect against zoster. Other animals
Humans are the only known species that the disease affects naturally. However, chickenpox has been caused in other primates, including chimpanzees and gorillas. Research
Sorivudine, a nucleoside analog, has been reported to be effective in the treatment of primary varicella in healthy adults (case reports only), but large-scale clinical trials are still needed to demonstrate its efficacy. There was speculation in 2005 that continuous dosing of aciclovir by mouth for a period of time could eradicate VZV from the host, although further trials were required to discern whether eradication was actually viable. See also
Measles

References
External links

Chickenpox at Curlie
Prevention of Varicella: Recommendations of the Advisory Committee on Immunization Practices (ACIP), 1996
Antiviral therapy of varicella-zoster virus infections, 2007
Epidemiology and Prevention of Vaccine-Preventable Diseases: Varicella, US CDCs "Pink Book"
Chickenpox at MedlinePlus