Chickenpox

About Chickenpox

Chickenpox varicella is a highly contagious disease caused by the varicella zoster virus VZV. Before routine vaccination, virtually all children contracted chickenpox. The disease presents with a characteristic itchy rash that progresses from macules to papules to vesicles to crusts, appearing in crops over 3 to 5 days. Lesions in different stages coexist, distinguishing chickenpox from smallpox where all lesions are in the same stage. The rash typically starts on the face and trunk, spreading to the extremities, and can involve mucous membranes. Associated symptoms include fever, fatigue, headache, and loss of appetite. The disease is transmitted through respiratory droplets and direct contact with vesicle fluid. Complications are more common in adults, infants, pregnant women, and immunocompromised individuals, and include bacterial superinfection of skin lesions, pneumonia, encephalitis, cerebellar ataxia, and Reye syndrome associated with aspirin use in children. Congenital varicella syndrome can occur if a pregnant woman is infected in the first or second trimester. The varicella vaccine, introduced in the US in 1995, is approximately 90 percent effective at preventing disease and nearly 100 percent effective at preventing severe disease. In countries with routine varicella vaccination, two doses are given in childhood, with schedules varying by country. Treatment is supportive, with antihistamines for itching and calamine lotion. Antivirals acyclovir are generally reserved for people at higher risk of complications. Aspirin is not given to children with chickenpox because of the risk of Reye syndrome.