Chickenpox is a highly contagious disease caused by the Varicella zoster virus, a member of the herpes virus family.
Almost everyone gets chickenpox by adulthood (more than 95% of Americans). The greatest number of cases of chickenpox occurs in the late winter and spring.
Chickenpox is transmitted to others by direct person-to-person contact, by droplet or airborne spread of discharges from an infected person's nose and throat or indirectly through articles freshly soiled by discharges from the infected person's lesions. The scabs themselves are not considered infectious.
The first symptoms include a slight fever, and feeling tired and weak. An itchy blister-like rash soon follows. The blisters become dry, crust over, and form scabs within 4 to 5 days. The average number of scabs is 300-400. The blisters tend to be more common on covered than on exposed parts of the body. They may appear on the scalp, armpits, trunk and even on the eyelids and in the mouth. Very mild infections occasionally occur in children. The disease is usually more serious in adults than in children.
Symptoms usually appear 14-16 days after exposure to the virus but could be up to 3 weeks.
A person is able to transmit chickenpox from 1-2 days (possibly 5 days) before onset of rash until all blisters have formed scabs. Contagiousness may be longer in people with altered immunity.
Chickenpox generally results in lifelong immunity. However, this infection may remain hidden and recur years later as Herpes zoster (shingles) in some adults and sometimes in children.
Approximately 10,000 hospitalizations and 100 deaths are due to chickenpox each year.
Yes. It is recommended that all children be routinely vaccinated at 12-15 months of age with a second dose administered at 4 through 6 years of age and that all susceptible children receive the vaccine before their 13th birthday (CDC Advisory Committee on Immunization Practices, the American Academy of Pediatrics and the American Academy of Family Physicians). Some adolescents and adults who have not had chicken pox may also want to be vaccinated. The vaccine is also approved for susceptible individuals within 3 days of exposure to a person contagious for chickenpox.
The best method to prevent further spread of chickenpox is for people infected with the disease to remain home and avoid exposing others who are susceptible. If they develop symptoms, they should remain home until 1 week after the rash starts or until the lesions become dry. Pay particular attention to avoiding unnecessary exposure of non immune newborns and immunodeficient patients to chickenpox. Children and others who have not already had chicken pox should be vaccinated. Effective antiviral medications are available to treat chickenpox.