Chickenpox and Shingles Tests
Chickenpox and shingles tests identify the presence of the varicella zoster virus (VZV) or antibodies to it, helping to confirm an active infection or determine immunity.
Overview
These tests check for the varicella zoster virus (VZV), also known as human herpesvirus 3. The first infection causes chickenpox. Once recovered, the virus remains dormant in nerve cells and can reactivate later in life as shingles (herpes zoster).
Types of Tests
- PCR (polymerase chain reaction) test: The most accurate method; looks for genetic material from VZV, usually via a swab of open blisters.
- Viral culture test: Grows cells from a swab sample in a lab; less accurate than PCR.
- Direct fluorescent antibody (DFA) test: A rapid test using fluorescent dye to identify VZV in a swab sample.
- Antibody test: A blood test checking for IgM (current/recent infection) or IgG (past exposure/immunity).
Why Testing is Needed
While visual exams are common, testing is often ordered for high-risk individuals, including pregnant women, infants, and those with weakened immune systems (e.g., HIV, cancer, organ transplant recipients, or those on immunosuppressive medications). Symptoms for both include a red, blistering rash, fever, headache, and sore throat.
Chickenpox rash typically starts on the chest, back, and face before spreading. Shingles rash is often painful and itchy, appearing in a band on one side of the body or face, preceded by pain or tingling.
Procedure and Risks
Testing involves either a blood draw from a vein or a swab of fluid from a blister. Both procedures are quick and carry minimal risk, primarily slight pain or bruising at the blood draw site.
Prevention
Vaccination is the primary prevention method:
- Chickenpox vaccine: Recommended for children (two doses) and adults who have never had the disease or the vaccine.
- Shingrix: A shingles vaccine recommended for healthy adults age 50 and older, and adults 19 and older with weakened immune systems. It is recommended even if you have already had shingles.