Oooh. Pirates! Mutants! No, wait… mutant pirates!
How about moving it to the Americas? Voudoun! Macumba! Condomblé!
This sounds like great fun.
Yeah there’s a lot of scope for some tiny island in the Caribbean Sea (the classic pirate location). Perhaps a penal colony abandoned to the plague? With the lack of authority on the island, it could present itself as a haven for pirates and strange folk, who end up mutated as well!