While on holiday in France from my work in Thailand, I thought I had a left upper molar infection. I wished I’d stocked up on some antibiotics (far too easy to purchase in resource poor settings, where they can least afford problems with drug resistance). The next day I diagnosed left maxillary sinusitis. The following day the supposed sinusitis was now on the left side of my nose as a 1.5 cm, red, slightly raised, circular lesion.

In Thailand superficial migrating skin lesions are caused by helminths. The commonest is cutaneous larva migrans, where humans are accidental …