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Research article - Peer-reviewed, 2020

Enhanced threat of tick-borne infections within cities? Assessing public health risks due to ticks in urban green spaces in Helsinki, Finland

Sormunen, Jani Jukka; Kulha, Niko; Klemola, Tero; Makela, Satu; Vesilahti, Ella-Maria; Vesterinen, Eero Juhani;

Abstract

Most tick-related studies in Europe have been conducted in nonurban areas, but ticks and tick-borne pathogens also occur in urban green spaces. From a public health perspective, risks regarding tick-borne infections should be studied in these urban areas, where contacts between infected ticks and humans may be more frequent than elsewhere, due to high human activity. We examined the risk of encountering an infected tick in urban green spaces in Helsinki, Finland. We collected ticks at nine sites throughout Helsinki, recorded the prevalence of several pathogens and identified areas with a high potential for contacts between infected ticks and humans. Moreover, we explored the relationship between the density ofBorrelia burgdorferisensu lato-infected ticks and locally diagnosed cases of borreliosis and compared the potential for human-tick encounters in Helsinki to those in nonurban areas in south-western Finland. During 34.8 km of cloth dragging, 2,417Ixodes ricinuswere caught (402 adults, 1,399 nymphs and 616 larvae). From analysed nymphs, we found 11 distinct tick-borne pathogens, with 31.5% of nymphs carrying at least one pathogen. Tick activity was highest in August and September, leading to the density of nymphs infected withB. burgdorferis.l., and concurrently infection risk, to also be highest during this time. Nymph densities varied between the sampling sites, with obvious implications to spatial variation in infection risk. While ticks and tick-borne pathogens were found in both Helsinki and nonurban areas in south-western Finland, the estimates of human activity were generally higher in urban green spaces, leading to a higher potential for human-tick contacts therein. The presence of ticks and tick-borne pathogens and high local human activity in urban green spaces suggest that they form potential foci regarding the acquisition of tick-borne infections. Risk areas within cities should be identified and knowledge regarding urban ticks increased.

Keywords

infections; lyme disease; parks; recreational; public health; tick bites; ticks

Published in

Zoonoses and Public Health

2020, volume: 67, number: 7, pages: 823-839
Publisher: WILEY

Authors' information

Sormunen, Jani Jukka
University of Turku
Kulha, Niko
University of Helsinki
Klemola, Tero
University of Turku
Makela, Satu
University of Turku
Vesilahti, Ella-Maria
University of Turku
Vesterinen, Eero
University of Turku
Vesterinen, Eero
Swedish University of Agricultural Sciences, Department of Ecology

Sustainable Development Goals

SDG11 Sustainable cities and communities

UKÄ Subject classification

Public Health, Global Health, Social Medicine and Epidemiology

Publication Identifiers

DOI: https://doi.org/10.1111/zph.12767

URI (permanent link to this page)

https://res.slu.se/id/publ/108135