All ticks carry the bacteria that cause Lyme disease

False. Only a proportion of I. ricinus nymphs are infected with the pathogen that causes Lyme disease – Borrelia burgdorferi s.l.. This proportion is influenced by the abundance of hosts that can carry and transmit the pathogen, as well as the abundance of immature ticks (larvae and nymphs) that can pick up the infection from one of these “reservoir (transmission) hosts”.

Field studies carried out in Scotland found the following proportions of infected ticks with Borrelia burgdorferi s.l.: (1) James et al. (2012), from a total of 13,250 nymphs 5.6% were infected (range 0.8–13.9%) (18). (2) Millins et al. (2016) from 3,800 nymphs tested, 1.7% were infected (range 0–6%) (20).