One of the curses which God warned would afflict the Israelites if they failed to obey his commands was 'painful boils' of the knees and legs 'spreading from the soles' of the feet 'to the top' of the head (Dt 28:35). Interestingly, Satan afflicted Job with exactly this condition despite his innocence (the same Hebrew word shechin is translated 'boil' and 'sore' respectively in Dt 28:35 and Jb 2:7).

Scabies can lead to secondary infection, but is ruled out as the head is not affected in adults. (Perhaps 'festering sores and the itch' (v29) is a better description of this.) Mycosis fungoides is a skin tumour which can cause necrotic ulcerating lesions but is fairly uncommon. The skin lesions in leprosy are anaesthetic. Parasitic skin infection, pemphigus and cutaneous lymphoma are remote possibilities but don't realty fit the description. Pustular psoriasis, which can be very painful and generalised, is rare but certainly possible.

Luke favours infected pustular eczema - in view of the fact that it is extremely common world-wide and can occur anywhere, all over the body. However he wonders if the answer may simply be 'painful boils' (staphyloccal pyoderma).