A 72-year-old man comes to the physician because of sharp pain of his right thorax for 3 days and a rash in a band-like distribution over his right chest for 1 day. He babysits his 4-year- old grandson who recently developed chickenpox. Physical examination shows a vesicular rash in a T8 dermatomal distribution. Which of the following is the most likely source of virus in this patient’s infection?
(A) Hematogenous dissemination from the respiratory tract
(B) New infection from the grandson by the respiratory route
(C) New infection from the skin of the grandson
(D) Reactivation of a latent infection from the patient’s dermal dendritic cells
(E) Reactivation of a latent infection from the patient’s dorsal root ganglion
Correct answer : (E) Reactivation of a latent infection from the patient’s dorsal root ganglion
Primary infection with HZV can only cause chicken pox. After primary infection, VZV is hypothesized to spread from mucosal and epidermal lesions to local sensory nerves. VZV then remains latent in the dorsal ganglion cells of the sensory nerves. Reactivation of VZV results in the clinically distinct syndrome of herpes zoster (i.e., shingles) and shingles can only occur in an individual who has had chicken pox earlier (mostly in younger age).
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