At a glance
Also known as
Varicella Zoster Virus; VZV; Herpes Zoster
Why get tested?
If your doctor suspects that you presently have, or recently had, chickenpox or shingles and a definitive diagnosis is necessary; to demonstrate to the varicella zoster virus (VZV) or the potential for re-activating a VZV infection prior to receiving drugs
When to get tested?
To check immune status and/or to identify an active infection; sometimes when a person has atypical and/or severe symptoms and the doctor wants to distinguish between a VZV infection and another cause; prior to an organ transplant or when a child, pregnant woman, or an person has been exposed to someone with chickenpox
A blood sample drawn from a vein in your arm for VZV antibody testing; to detect the virus itself, a sample of fluid from a blister (), blood, , or other body fluid or
Test preparation needed?
What is being tested?
Tests for chickenpox and shingles are performed to detect and diagnose either a current or past infection with the that causes these conditions, the varicella zoster virus (VZV). Most often, testing is not necessary because a diagnosis of active infection can be made from clinical and , but in some patients with atypical skin lesions, a diagnostic test helps to confirm the infection. In organ transplant recipients or pregnant women, the tests may be useful to diagnose a current infection or to determine status of .
Varicella zoster is a member of the herpes virus family. It is very common and the primary infection is highly contagious, passing from person to person through respiratory secretions. VZV causes chickenpox in the young and in adults who have not been previously exposed. Usually, about two weeks after exposure to the virus, an itchy rash emerges, followed by the formation of pimple-like papules that become small, fluid-filled blisters (). The vesicles break, form a crust, and then heal. This process occurs in two or three waves or “crops” of several hundred vesicles over a few days.
Once the initial infection has resolved, the virus becomes , persisting in sensory nerve cells. The person develops during the infection that usually prevent them from getting chickenpox again during subsequent exposures. However, later in life and in those with compromised immune systems, VZV can reactivate, migrating down the nerve cells to the skin and causing shingles (also known as herpes zoster). Symptoms of shingles include a mild to intense burning or itching pain in a band of skin at the waist, the face, or another location. It is usually in one place on one side of the body but can also occur in multiple locations. Several days after the pain, itching, or tingling begins, a rash, with or without vesicles, forms in the same location. In most people, the rash and pain subside within a few weeks, and the virus again becomes latent. A few may have pain that lingers for several months.
Most cases of chickenpox and shingles resolve without complications. However, VZV encephalitis can occur during chicken pox with or without the presence of a rash. In people, such as those with HIV/AIDS or those who have had an organ transplant, chicken pox can be more severe and long-lasting, with greater risks of complications, dissemination of the virus or frequent episodes of VZV reactivation.
In pregnant women, the effects of exposure to VZV on a fetus or newborn depend on when it occurs and on whether or not the mother has been previously exposed. In the first 20 to 30 weeks of pregnancy, a primary VZV infection may, rarely, cause abnormalities in the fetus. If the infection occurs one to three weeks before delivery, the baby may be born with or acquire chickenpox after birth, although the baby may be partially protected by the mother’s antibodies. If a newborn is exposed to VZV at birth and does not have maternal antibody protection, then the VZV infection can be fatal.
Before the introduction and widespread use of a varicella zoster vaccine nearly everyone became infected by VZV by the time they were an adult. While VZV is still present in its latent form in most adults, according to the Centers for Disease Control and Prevention (USA), the incidence of new cases of chickenpox in children has declined by about 90%. In Australia prior to the introduction of the varicella vaccine about 75% of children caught chickenpox by the age of 12. Since the introduction of free childhood vaccination in 2005 there has been a major decline in the incidence of new cases in children.
How is the sample collected for testing?
The sample required depends on whether testing is being done to determine the presence of or to detect the itself and on the health status of the patient. Antibody testing requires a blood sample drawn from a vein in the arm. Viral detection may be done on a variety of samples, including a sample of fluid, blood, , other fluid, or .
Is any test preparation needed to ensure the quality of the sample?
No test preparation is needed.