Biology of Ixodes species ticks in relation to tick-borne zoonoses.

At least six tick-borne zoonoses are transmitted by members of the Ixodes ricinus species complex in northern hemisphere temperate regions, and include the relatively recently emerged diseases, Lyme borreliosis and ehrlichiosis. An understanding of the biology of these ticks is essential for the prevention and control of the zoonoses they transmit and this review summarises established knowledge in addition to addressing recent work on host specificity of ticks, inter- and intra-specific biological variation and factors affecting tick distribution and abundance.