Fig. 1

The successful transmission cycle of Borrelia burgdorferi s.l. requires both a competent vertebrate reservoir host and a competent Ixodes spp. tick vector. 1a An infected nymph feeds on a naïve host. 1b During fluid exchange between the nymph and the host, the pathogen is inoculated in the host. 2 The pathogen disseminates in host tissues and establishes a lasting infection. 3a A newly hatched larva feeds on the infected host and 3b imbibes the pathogen. 4 After a full blood meal, the infected larva detaches from the host and moults into an infected nymph. Created with BioRender.com