Herpes Zoster or Shingles represents reactivation and replicationn of Latent infection in:: (A) Dorsal Root Ganglion, (B) Anterior Horn Cell, (C) Peripheral nerve, (D) Epithelium of Skin
Answer is A. Herpes zoster (shingles) is caused by the reactivation and multiplication (Replication) of the Varicella -zoster virus (VZV) in the dorsal root ganglion. Herpes zoster, is a localized disease characterized by unilateral radicular pain and a vesicular rash limited to the area of skin innervated by a single dorsal root or cranial sensory ganglion. Reactivation of Latent Varicella Zoster: Varicella Zoster Virus remains latent in sensory ganglia including dorsal root ganglia of the spinal cord (most frequently) and other ganglion including trigeminal ganglion and/or geniculate ganglion. Chicken Pox: Virus enters sensory nerve endings and travels in retrograde fashion to sensory ganglia where it remains latent. Reactivation/replication in dorsal root ganglion: Virus travels back from ganglia along sensory nerves to the peripheral nerves of sensory dermatomes causing &;shingles&; = Herpes Zoster/Shingles: Unilateral vesicular eruption within a dermatome associated with severe pain. (The dermatomes from T3 and L3 are most frequently involved) Reactivation/replication in Trigeminal Ganglion: Virus travels back from trigeminal ganglia, most often along first division of cranial nerve V causing Zoster Ophthalmicus. Other divisions may also be involved & lesions may appear on the face, in the mouth or on the tongue. = Herpes Zoster Ophthalmicus Reactivation/replication in geniculate ganglion: Virus travels back from the geniculate ganglion along the sensory distribution of facial nerve causing Herpes Zoster Oticus or the &;Ramsay Hunt Syndrome&; = Ramsay Hunt Syndrome: Pain and vesicles appear in the external auditary canal. Patients lose their sense of taste in anterior 2/3rd of the tongue and develop ipsilateral facial nerve palsy. Ref: Harrison, Jawetz Microbiology, Rubin&;s Pathology