Chickenpox

The varicella zoster virus is a member of the herpes virus family. Varicella zoster virus causes the infectious disease known by the common name chickenpox. The virus passes from person to person through contact transmission with an incubation period of 10 to 20 days from exposure.

Physicians usually make a clinical diagnosis of chickenpox; the infected person shows signs such as fever or lesions and might complain of loss of appetite, malaise, or pain. Chickenpox can be confirmed with laboratory tests for varicella zoster virus including enzyme-linked immunosorbent assay (ELISA), which uses specific antibodies to identify the corresponding antigen, fluorescent antibody (a reaction combining fluorescing dyes attached to antibodies that glow when attached to the complementary antigen in the serum), and hemagglutination reaction where antigens and antibodies combine to form a clump.

Most children who develop chickenpox experience a fairly benign form. They may develop a low-grade fever and malaise. Raised red lesions form a rash on the trunk, neck, and face. During this time, a physician might recommend a lotion like calamine or antihistamines to relieve the itching. While the lesions are forming and rupturing, the varicella zoster virus is highly contagious to those persons who have never had the virus. The infected person may continue to develop new lesions from one to five days after the first breakout. The lesions crust over and fall off in approximately 14 days from eruption.

Although infrequent, severe complications of the illness may include Reye's syndrome with concomitant aspirin therapy, pneumonia, bacterial superinfection, or encephalitis. Infected adults often experience more severe symptoms and are at a higher potential risk for additional adverse effects. Women in the first trimester of pregnancy appear to be more prone to the development of pneumonia requiring intravenous antiviral treatment and respiratory support. Infection with varicella zoster virus during the second and third trimesters is less life threatening. The antibodies cross the placenta providing protection to the fetus.

To protect immunocompromised individuals and pregnant women, varicella zoster immune globulin can be administered. Varicella zoster immune globulin contains the antibodies for the virus and will provide [Page 381]temporary and immediate passive immunity for susceptible individuals within four days of exposure. Varicella zoster immune globulin can also be given to premature infants and newborns when the mothers give birth during active chickenpox infection and before antibodies have formed in the mother's blood. A test for confirmation of the virus can be performed on umbilical cord blood.

Becoming ill with a disease and recovering results in lifelong immunity from having it again. This type of immunity is called acquired immunity. The body adds antibodies to the specific antigen to its arsenal for fighting off disease. While a person cannot have chickenpox again, the virus becomes latent, ascending to the dorsal root ganglia to hide from the immune system and the antibodies now present in the body to combat infection.

Varicella zoster virus has two different life cycles: a productive or active phase and a latent phase. The productive phase occurs in skin cells, where the virus can grow and multiply. This is also the infectious phase of the virus. The latent phase occurs in nerve cells.

...