The Unexpected Holiday Souvenir: The Public Health Risk to UK Travellers from Ticks Acquired Overseas

Abstract

Overseas travel to regions where ticks are found can increase travellers' exposure to ticks and pathogens that may be unfamiliar to medical professionals in their home countries. Previous studies have detailed non-native tick species removed from recently returned travellers, occasionally leading to travel-associated human cases of exotic tick-borne disease. There are 20 species of tick endemic to the UK, yet UK travellers can be exposed to many other non-native species whilst overseas. Here, we report ticks received by Public Health England's Tick Surveillance Scheme from humans with recent travel history between January 2006 and December 2018. Altogether, 16 tick species were received from people who had recently travelled overseas. Confirmed imports (acquired outside of the UK) were received from people who recently travelled to 22 countries. Possible imports (acquired abroad or within the UK) were received from people who had recently travelled to eight European countries. Species-specific literature reviews highlighted nine of the sixteen tick species are known to vector at least one tick-borne pathogen to humans in the country of acquisition, suggesting travellers exposed to ticks may be at risk of being bitten by a species that is a known vector, with implications for novel tick-borne disease transmission to travellers.

Keywords: Amblyomma; Amblyomma americanum; Dermacentor; Hyalomma; Ixodes; Ixodes ricinus; Rhipicephalus; tick-borne pathogens.

Figure 1

Seasonality of tick records received by the Tick Surveillance Scheme from people with a history of travel that were acquired in South America (yellow), Asia (blue-grey), Australia (green), Africa (beige) and North America (white), and possible imports from Europe (light grey) and confirmed imports from Europe (dark grey).

Figure 2

Map showing recent travel history of people submitting confirmed and possible imported tick records to Public Health England’s Tick Surveillance Scheme between January 2006 and December 2018. The numbers of records received from each country are indicated by the size of the circle. Two records are not shown: one record that was acquired in either Holland, Germany or France; another record that was acquired in either the Canadian Rockies or north-western USA (see Table 1). Maps have been reproduced with permission from Ordnance Survey on behalf of Her Majesty’s Stationery Office, © Crown Copyright and database right. 2020. All rights reserved. Ordnance Survey License number 100016969/100022432.