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. 2023 Mar;37(1):96-104.
doi: 10.1111/mve.12612. Epub 2022 Oct 14.

Possible expansion of Ixodes ricinus in the United Kingdom identified through the Tick Surveillance Scheme between 2013 and 2020

Sara L Gandy  1 , Kayleigh M Hansford  1   2 , Jolyon M Medlock  1   2
Affiliations

Possible expansion of Ixodes ricinus in the United Kingdom identified through the Tick Surveillance Scheme between 2013 and 2020

Sara L Gandy et al. Med Vet Entomol. 2023 Mar.

Abstract

The tick Ixodes ricinus (Ixodida: Ixodidae, Linnaeus) is the main vector of several pathogens including Borrelia burgdorferi s.l. (agent of Lyme borreliosis) and tick-borne encephalitis virus. Its distribution depends on many factors including suitable habitat, climate and presence of hosts. In this study, we present records of I. ricinus bites on humans, dogs (Canis lupus familiaris; Carnivora: Canidae, L.) and cats (Felis catus; Carnivora: Felidiae, L.) in the United Kingdom (UK) obtained through the Tick Surveillance Scheme between 2013 and 2020. We divided the UK into 20 km x 20 km grids and 9.2% (range 1.2%-30%) of grids had at least one record every year since 2013. Most regions reported a yearly increase in the percentage of grids reporting I. ricinus since 2013 and the highest changes occurred in the South and East England with 5%-6.7% of new grids reporting I. ricinus bites each year in areas that never reported ticks before. Spatiotemporal analyses suggested that, while all regions recorded I. ricinus in new areas every year, there was a yearly decline in the percentage of new areas covered, except for Scotland. We discuss potential drivers of tick expansion, including reforestation and increase in deer populations.

Keywords: Borrelia burgdorferi s.l; distribution; surveillance; vector; vector-borne disease.

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Conflict of interest statement

The authors report no potential conflict of interest.

Figures

FIGURE 1
FIGURE 1
Percentage of grids with at least one record of Ixodes ricinus for each nomenclature of territorial units for statistics 1 in the UK between 2013 and 2020. The dark blue colour represents the percentage of grids covered per year and the light blue represents the cumulative percentage of area covered since 2013.
FIGURE 2
FIGURE 2
Predicted percentage of grids with an Ixodes ricinus record between 2013 and 2020 in Central England, North England, Scotland, South England and Wales. Shaded areas represent 95%CI.
FIGURE 3
FIGURE 3
Maps showing the possible expansion of Ixodes ricinus records in each region of the UK. The map on the left shows the percentage of grids recording a tick bite between 2002 and 2012 (light grey), the middle map shows the percentage of new grids covered (dark grey) for 2013–2016 and the map on the right shows the percentage of new grids covered (blue) for 2017–2020 compared to previous years. NI: Northern Ireland, NE: North east, NW: North west, YH: Yorkshire and the Humber, WM: West midlands, EM: East midlands, EE: East England, SW: South west, SE: South east, GL: Greater London. Contains ordnance survey data ©crown copyright and database right 2022. Contains National Statistics data ©crown copyright and database right 2022.
See this image and copyright information in PMC

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