Autoinfection

One day last May I awoke, annoyed to find that I was starting a new herpes simplex lesion. I have been used to recurrent labial herpes HSV-1 for some 60 years but was a little surprised that this was not the usual lip lesion but was on my chin, 1 cm in diameter and about 2 cm below the angle of my mouth.

A few hours later the familiar scalp hyperaesthesia (allodynia) started. But it was not familiar. Instead of affecting the usual frontal (trigeminal innervated) area, it was the posterior half of my scalp extending down the nape of my neck and laterally down to my ear on the contralateral side—that is, the dermatome supplied by the second cervical …