The causative agent of chickenpox and shingles is which virus?

• A. Varicella zoster virus
• B. Herpes simplex virus
• C. Cytomegalovirus
• D. Epstein-Barr virus

Answer: (A)

Varicella zoster virus is the one virus that causes both chickenpox and shingles. It’s a herpesvirus that establishes latency in sensory ganglia after the primary infection. When someone first encounters it, the virus produces varicella (chickenpox), with the characteristic vesicular rash that spreads from trunk outward. After the skin lesions heal, the virus isn’t gone; it hides in dorsal root or cranial nerve ganglia. Later in life, or when immunity wanes, the virus can reactivate and travel along a sensory nerve to the corresponding dermatomal area, causing herpes zoster (shingles), which presents as a painful, band-like rash. The other viruses listed—herpes simplex virus, cytomegalovirus, and Epstein-Barr virus—cause different diseases (HSV mainly mucocutaneous or genital lesions; CMV and EBV illnesses such as mononucleosis or specific organ infections) and are not responsible for the classic varicella-zoster–related diseases.