Ticks, particularly Ixodes ricinus, can carry Borrelia burgdorferi sensu lato, which causes Lyme disease.
Over June and July 2013 researchers used a variety of testing methods including dragging blankets across the ground and using flags attached to trousers to sample 360 areas, testing whether ticks would attach to the materials. They found no ticks in Wimbledon Common or Hampton Court but found 1109 ticks in the samples from Richmond Park and nine ticks at Bushy Park.
At Richmond Park, ticks were present in samples taken from areas with increased soil moisture and mat depth and lower canopy humidity. The insects were more abundant on cooler ground with longer grass. At Bushy Park, thicker mat depth predicted tick presence and warmer ground correlated with tick absence.
A total of 279 ticks were screened for the presence of B. burgdorferi. Despite the high numbers of ticks at Richmond Park, just 2.14 per cent of nymphs were found to be carrying the bacteria.
But the researchers said their findings, particularly at Richmond Park, "highlight the need for appropriate communication of the associated risk to the general public frequenting these recreational areas".
"Given its high footfall and proximity to Richmond Park, tick presence should be routinely monitored at Wimbledon Common. Despite suitable hosts for I. ricinus, the abiotic conditions appear to be unfavourable at Hampton Court and the consequent risk to the general public is low. At Richmond and Bushy Parks, I. ricinus is irrefutably present and preventative measures should be taken to avoid tick bites."
The Royal Parks should be encouraged to provide leaflets on the risk of Lyme borreliosis and further activities to increase public awareness, the researchers said.An advice sheet on ticks published by The Royal Parks (PDF) suggests sticking to paths, avoiding dense vegetation and tucking trousers into socks to avoid being bitten by ticks.