Tick abundances in South London parks and the potential risk for Lyme borreliosis to the general public.

Tick abundances and prevalences of infection with Borrelia burgdorferi sensu lato, the causative agent of Lyme disease, were investigated in four South London parks. A total of 360 transects were sampled using three methods of collection (blanket, leggings and flags) simultaneously. No ticks were found on Wimbledon Common or at Hampton Court, but 1118 Ixodes ricinus (Ixodida: Ixodidae) ticks were collected at Richmond and Bushy Parks. At Richmond Park, lower canopy humidity [odds ratio (OR) 0.94; P = 0.005], increased mat depth (OR 1.15; P < 0.001) and increased soil moisture (OR 1.40; P = 0.001) predicted the presence of I. ricinus, and increased sward height [incidence rate ratio (IRR) 1.01; P = 0.006] and decreased ground temperature (IRR 0.90; P = 0.009) predicted increased abundance. At Bushy Park, thicker mat depth predicted tick presence (OR 1.17; P = 0.006) and increasing temperature correlated with tick absence (OR 0.57; P = 0.023). A total of 279 ticks were screened for the presence of B. burgdorferi using quantitative polymerase chain reaction. Point prevalences of 0% for larvae (n = 78), 2.14% for nymphs (n = 174) and 0% for adult ticks (n = 7) related to an acarological risk of 0.22 infected ticks per 40 m transect in Richmond Park. The abundance of ticks and the acarological risk, particularly at Richmond Park, highlight the need for appropriate communication of the associated risk to the general public frequenting these recreational areas.