Of any ranked list of nasty diseases transmitted by mosquitoes, ticks and fleas in the Western world, Borrelia burgdorferi, would have to lie near the top. These bacteria cause Lyme disease, which was first recognised in the US in the early 1970s among patients in Lyme, Connecticut. However, the oldest known case was the Tyrolean Iceman, a 5,300-year-old Copper-age mummified individual, discovered in the Italian Alps.