September 5, 2013 Dr. Larry Jaeger is the medical director of Advanced Dermatology of New York, PC and specializes in the area of Medical, Cosmetic and Surgical Dermatology. Chicken pox is caused by the varicella-zoster virus (also known as the Human Herpes Virus 3). The infection causes a widespread eruption of small red, itchy blisters (vesicles). The vast majority of infections occur before age 10. The virus is spread by direct contact and respiratory route (sneezing). The rash does not appear until 10 to 21 days after infection. The patient is likely infectious (can spread the virus) 4 days prior and 5 days after the rash appears. The child may have low grade fever, malaise, and headache. The severity of infection is dependent on the age of the patient. The older the patient the more severe the infection can be. Children and adults can have severe complications and even die from the infection although it is not common. Simple bacterial infection of the skin lesions is the most common complication. Aspirin is absolutely prohibited in children with chickenpox as Reye’s syndrome can cause neurologic damage and liver failure. As with any infection, immunosuppression can allow a more severe infection. The infection is usually identified by a physician but may be verified with several different laboratory tests. Antiviral medicine should be started early to help reduce the severity of the disease and decrease the chance of spreading it. With or without treatment immunity is lifelong. The reactivation of varicella-zoster virus in the elderly is known as shingles and is often due to immunosuppression. Women who are pregnant or trying to get pregnant should not be exposed to anybody who has chickenpox. Serious complications and congenital malformations may result. A vaccine for varicella-zoster is available and is recommended.