title: Diversifying forest communities may change Lyme disease risk: extra dimension to the dilution effect in Europe.
abstract: Lyme disease is caused by bacteria of the Borrelia burgdorferi genospecies complex and transmitted by Ixodid ticks. In North America only one pathogenic genospecies occurs, in Europe there are several. According to the dilution effect hypothesis (DEH), formulated in North America, nymphal infection prevalence (NIP) decreases with increasing host diversity since host species differ in transmission potential. We analysed Borrelia infection in nymphs from 94 forest stands in Belgium, which are part of a diversification gradient with a supposedly related increasing host diversity: from pine stands without to oak stands with a shrub layer. We expected changing tree species and forest structure to increase host diversity and decrease NIP. In contrast with the DEH, NIP did not differ between different forest types. Genospecies diversity however, and presumably also host diversity, was higher in oak than in pine stands. Infected nymphs tended to harbour Borrelia afzelii infection more often in pine stands while Borrelia garinii and Borrelia burgdorferi ss. infection appeared to be more prevalent in oak stands. This has important health consequences, since the latter two cause more severe disease manifestations. We show that the DEH must be nuanced for Europe and should consider the response of multiple pathogenic genospecies.
authors.affiliation: Forest & Nature Laboratory,Department of Forest and Water Management,Ghent University,Geraardsbergsesteenweg 267,9090 Melle-Gontrode,Belgium.
authors.forename: Sanne C
authors.initials: SC
authors.lastname: Ruyts
authors.affiliation: Forest & Nature Laboratory,Department of Forest and Water Management,Ghent University,Geraardsbergsesteenweg 267,9090 Melle-Gontrode,Belgium.
authors.forename: Evy
authors.initials: E
authors.lastname: Ampoorter
authors.affiliation: Centre for Infectious Disease Control Netherlands, National Institute for Public Health and Environment,P.O. Box 1, 3720 BA Bilthoven,The Netherlands.
authors.forename: Elena C
authors.initials: EC
authors.lastname: Coipan
authors.affiliation: Forest & Nature Laboratory,Department of Forest and Water Management,Ghent University,Geraardsbergsesteenweg 267,9090 Melle-Gontrode,Belgium.
authors.forename: Lander
authors.initials: L
authors.lastname: Baeten
authors.affiliation: Evolutionary Ecology Group,Department of Biology,University of Antwerp,Groenenborgerlaan 171,2020 Antwerp,Belgium.
authors.forename: Dieter
authors.initials: D
authors.lastname: Heylen
authors.affiliation: Centre for Infectious Disease Control Netherlands, National Institute for Public Health and Environment,P.O. Box 1, 3720 BA Bilthoven,The Netherlands.
authors.forename: Hein
authors.initials: H
authors.lastname: Sprong
authors.affiliation: Evolutionary Ecology Group,Department of Biology,University of Antwerp,Groenenborgerlaan 171,2020 Antwerp,Belgium.
authors.forename: Erik
authors.initials: E
authors.lastname: Matthysen
authors.affiliation: Forest & Nature Laboratory,Department of Forest and Water Management,Ghent University,Geraardsbergsesteenweg 267,9090 Melle-Gontrode,Belgium.
authors.forename: Kris
authors.initials: K
authors.lastname: Verheyen
mesh_terms: D000818:Animals; D001096:Arachnid Vectors / Q000469:parasitology* / Q000502:physiology; D001530:Belgium / Q000453:epidemiology; D044822:Biodiversity; D025065:Borrelia burgdorferi / Q000235:genetics / Q000502:physiology*; D005060:Europe / Q000453:epidemiology; D065928:Forests; D018884:Ixodes / Q000469:parasitology* / Q000502:physiology; D008193:Lyme Disease / Q000453:epidemiology* / Q000382:microbiology* / Q000635:transmission; D009656:North America / Q000453:epidemiology; D009758:Nymph / Q000382:microbiology; D028223:Pinus / Q000382:microbiology; D016133:Polymerase Chain Reaction; D029963:Quercus / Q000382:microbiology
keywords: Biodiversity; Borrelia burgdorferi genospecies; Ixodes ricinus; Lyme disease; dilution effect; disease ecology; forest diversification; public health