Green’s Dictionary of Slang

(W.I.) having a skin covered in repulsive sores; thus have cocobay on top of yaws, to add new troubles to a situation that seemed bad enough already.

[1873		C. Rampini Letters from Jamaica 26: Of beggars we saw very few, and these were chiefly lepers [...] the disease which goes by the African name of ‘cocobay’].
1996		Allsopp Dict. Carib. Eng. Usage.