Heterogeneity in the abundance and distribution of Ixodes ricinus and Borrelia burgdorferi (sensu lato) in Scotland: implications for risk prediction

Millins, C. , Gilbert, L., Johnson, P. , James, M., Kilbride, E., Birtles, R. and Biek, R. (2016) Heterogeneity in the abundance and distribution of Ixodes ricinus and Borrelia burgdorferi (sensu lato) in Scotland: implications for risk prediction. Parasites and Vectors, 9, 595. (doi:10.1186/s13071-016-1875-9) (PMID:27876087) (PMCID:PMC5084683)

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Abstract

Background: Cases of Lyme borreliosis, a vector-borne zoonosis caused by bacteria in the Borrelia burgdorferi (sensu lato) species group, have increased in recent years in Europe. Knowledge of environmental factors associated with abundance of the tick vector Ixodes ricinus and the pathogen B. burgdorferi (s.l.) is of interest to understand responses to environmental changes, predict variation in risk and to inform management interventions. Methods: Nineteen woodland sites across Scotland were surveyed in 2012 for B. burgdorferi (s.l.) infection in questing I. ricinus nymphs (n = 200 per site), deer abundance and vegetation. Climatic factors were extracted for each site. Six additional sites were surveyed for questing nymphs in both 2012 and 2013 (n = 200 per site and year) to test for variation in B. burgdorferi (s.l.) prevalence between years. Results: The mean prevalence of B. burgdorferi (s.l.) across 19 sites was 1.7% (95% CI: 1.4–2.2%; range 0–6%), all four genospecies known to be present in the UK were detected: B. garinii, B. afzelii, B. burgdorferi (sensu stricto) and B. valaisiana. A higher prevalence of B. burgdorferi (s.l.), higher densities of nymphs and higher densities of infected nymphs were found at sites with warmer climates, estimated with growing degree-days. No association between infection prevalence in nymphs and woodland type (semi-natural mixed vs coniferous) or deer density was found. At six sites sampled in 2012 and 2013, there was a significant increase in B. afzelli prevalence at two sites and a decrease in B. garinii prevalence at one site. Conclusions: This study highlights challenges for the prediction of risk of Lyme borreliosis, reflecting the sensitivity of both pathogen and vector ecology to habitat, host and climatic factors. Significant changes in the prevalence of individual genospecies at sites monitored across time are likely to be due to variability in the host community composition between years. Our results indicate the importance of monitoring dynamic variables such as reservoir host populations as well as climate and habitat factors over multiple years, to identify environmental factors associated with Lyme borreliosis risk

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Biek, Dr Roman and Johnson, Dr Paul and Millins, Dr Caroline and Kilbride, Mrs Elizabeth and Gilbert, Dr Lucy
Authors: Millins, C., Gilbert, L., Johnson, P., James, M., Kilbride, E., Birtles, R., and Biek, R.
College/School:College of Medical Veterinary and Life Sciences > Institute of Biodiversity Animal Health and Comparative Medicine
College of Medical Veterinary and Life Sciences > School of Veterinary Medicine
Journal Name:Parasites and Vectors
Publisher:BioMed Central
ISSN:1756-3305
ISSN (Online):1756-3305
Copyright Holders:Copyright © 2016 The Authors
First Published:First published in Parasites and Vectors 9: 595
Publisher Policy:Reproduced under a Creative Commons License

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
500191BBSRC Doctoral Training Grant 2009-15Massimo PalmariniBiotechnology and Biological Sciences Research Council (BBSRC)BB/F016786/1MVLS III - CENTRE FOR VIRUS RESEARCH