The outbreak of louse-born relapsing fever is just the latest re-emergence of diseases long thought exterminated in Europe, carried back to the continent by a great migratory movement of millions of people from Africa and Asia. Particularly associated with Ethiopia, Sudan, Eritrea, and Somalia, the extremely contagious bacteria causes severe illness and can be fatal in 30 to 70 per cent of cases, according to the Centre for Disease Control and Prevention.