Relapsing fever revisited: New insights into neglected borrelial infections

Why revisit our understanding of relapsing fever and their causative spirochaetes? We have seen many existing paradigms of relapsing fever borreliosis challenged over recent years, largely facilitated through technological molecular biological improvements. Concepts that were believed for many years are now being questioned; from the origins of B. recurrentis, the epidemic form of relapsing fever, through to the one-tick-one Borrelia model. Furthermore, the description of relapsing fever borreliae such as B. miyamotoi transmitted by hard tick species and increasing reports of new borrelial species have prompted a re-evaluation of existing knowledge. Within this narrative review, we overview existing knowledge of relapsing fever ecology, epidemiology, diagnostics, disease and prevention, and explore several research gaps worthy of further research.