Shingles is a disease that results from a reactivation of the herpes zoster virus, which is responsible for causing chickenpox. The body is never able to completely eliminate the virus, which can allow the virus to reactivate. Shingles can occur only in patients who have previously had chickenpox. Shingles can usually be diagnosed based on the characteristic pain and rash it causes, but there are some tests for a more definitive diagnosis.
Viral Culture
As Lab Tests Online explains, one test that can detect shingles is called a viral culture. If the herpes zoster virus infects the skin, it will typically cause small fluid-filled pockets, called vesicles, to appear in the skin. A viral culture involves taking some of the fluid from these vesicles. Some of this fluid is then added to a culture of live cells. If the herpes zoster virus is causing the skin problems, it will infect the cell culture and multiply. The virus can then be isolated and identified to see if the patient is suffering from shingles. This test is sensitive, but it can take a few days to be completed and works best with a fresh cell sample.
Immunofluorescence
Another test for shingles is called the immunofluorescence test. In this test, a skin sample is taken from the patient and then special proteins called antibodies are used to try to identify the virus. The antibodies are specially made proteins that will bind only to the herpes zoster virus. These antibodies are also designed to fluoresce (emit light) when they are stimulated by special wavelengths of light. The immunofluorescence assay works by incubating the skin sample with these antibodies and then washing off any unbound antibodies. The skin sample is then examined using a special fluorescent microscope, which will be able to identify any antibodies bound to the tissue sample, indicating a herpes zoster infection. This kind of assay is very fast, but it is less sensitive than a viral culture, meaning there is a greater chance of it missing a herpes zoster infection.
DNA Analysis
Another test to diagnose shingles (based on a skin sample from the infected area) is to look for viral DNA. The simplest way of doing this uses a technique called polymerase chain reaction (PCR). This biological technique rapidly replicates specific stretches of DNA. The test can be tweaked so that it is set to act on stretches of DNA that are unique to the herpes zoster virus. This technique allows for the rapid detection of viral DNA if it is causing the patient's symptoms. This test is expensive, however, and according to the "New York Times," it is used only in unusual cases, such as when the disease is affecting the nervous system.
