Dataset Information

Using Landscape Analysis to Test Hypotheses about Drivers of Tick Abundance and Infection Prevalence with Borrelia burgdorferi.

ABSTRACT: Patterns of vector-borne disease risk are changing globally in space and time and elevated disease risk of vector-borne infection can be driven by anthropogenic modification of the environment. Incidence of Lyme disease, caused by the bacterium Borrelia burgdorferi sensu stricto, has risen in a number of locations in North America and this increase may be driven by spatially or numerically expanding populations of the primary tick vector, Ixodes scapularis. We used a model selection approach to identify habitat fragmentation and land-use/land cover variables to test the hypothesis that the amount and configuration of forest cover at spatial scales relevant to deer, the primary hosts of adult ticks, would be the predominant determinants of tick abundance. We expected that land cover heterogeneity and amount of forest edge, a habitat thought to facilitate deer foraging and survival, would be the strongest driver of tick density and that larger spatial scales (5-10 km) would be more important than smaller scales (1 km). We generated metrics of deciduous and mixed forest fragmentation using Fragstats 4.4 implemented in ArcMap 10.3 and found, after adjusting for multicollinearity, that total forest edge within a 5 km buffer had a significant negative effect on tick density and that the proportion of forested land cover within a 10 km buffer was positively associated with density of I. scapularis nymphs. None of the 1 km fragmentation metrics were found to significantly improve the fit of the model. Elevation, previously associated with increased density of I. scapularis nymphs in Virginia, while significantly predictive in univariate analysis, was not an important driver of nymph density relative to fragmentation metrics. Our results suggest that amount of forest cover (i.e., lack of fragmentation) is the most important driver of I. scapularis density in our study system.

SUBMITTER: Ferrell AM

PROVIDER: S-EPMC5923779 | biostudies-literature | 2018 Apr

REPOSITORIES: biostudies-literature

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Using Landscape Analysis to Test Hypotheses about Drivers of Tick Abundance and Infection Prevalence with Borrelia burgdorferi.

Ferrell A Michelle AM Brinkerhoff R Jory RJ

International journal of environmental research and public health 20180412 4

Patterns of vector-borne disease risk are changing globally in space and time and elevated disease risk of vector-borne infection can be driven by anthropogenic modification of the environment. Incidence of Lyme disease, caused by the bacterium <i>Borrelia burgdorferi</i> sensu stricto, has risen in a number of locations in North America and this increase may be driven by spatially or numerically expanding populations of the primary tick vector, <i>Ixodes scapularis</i>. We used a model selectio ...[more]

PMID: 29649156

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Project description:Lyme disease (LD) is a common arthropod-borne inflammatory disorder prevalent in the northern hemisphere. LD is caused by a spirochete named Borrelia burgdorferi s.l., which is transmitted to humans by ticks. Climate, environment, and other factors affect land use; recreational-behavior changes affect human contact with infected ticks. Studies in Europe and North America have looked at these aspects, but studies in Asia have not. We searched databases to identify all relevant abstracts published until March 2021. A meta-analysis was undertaken using the standard methods and procedures established by the Cochrane Collaboration. Ninety-one articles were included in our meta-analysis. The literature search identified data from nine countries (China, Japan, Malaysia, Mongolia, Pakistan, Russia Siberia region, South Korea, Thailand and Turkey). Furthermore, 53,003 ticks from six genera (Amblyomma, Dermacentor, Haemaphysalis, Hyalomma, Ixodes and Rhipicephalus) were inspected for infection with B. burgdorferi. The pooled prevalence was 11.1% (95% CI = 8.3-14.2%). Among the nine countries, China had the most studies (56) and Malaysia had the highest infection rate (46.2%). Most infected ticks were from the genera Ixodes and Haemaphysalis. Ticks of the genus Ixodes had the highest infection rate (16.9%). Obvious heterogeneity was noted in our meta-analysis. We analyzed the heterogeneity with regard to countries, genera, time points, and detection methods. This study suggests that Ixodes, Haemaphysalis and Dermacentor may be the most common tike of B. burgdorferi-positive in Asia. The highest proportion of ticks infected by B. burgdorferi were from the genus Ixodes. This meta-analysis is the first attempt to explain the B. burgdorferi infection of hard-body ticks in Asia. The infection rate for each country and infection rate of different tick genera were analyzed: there were large differences between them. The literature is concentrates mainly on East Asia, and data are limited. Our study can provide a reference for a more comprehensive and in-depth investigation of ticks in Asia infected by B. burgdorferi spirochetes.

Project description:The effect of biodiversity declines on human health is currently debated, but empirical assessments are lacking. Lyme disease provides a model system to assess relationships between biodiversity and human disease because the etiologic agent, Borrelia burgdorferi, is transmitted in the United States by the generalist black-legged tick (Ixodes scapularis) among a wide range of mammalian and avian hosts. The 'dilution effect' hypothesis predicts that species-poor host communities dominated by white-footed mice (Peromyscus leucopus) will pose the greatest human risk because P. leucopus infects the largest numbers of ticks, resulting in higher human exposure to infected I. scapularis ticks. P. leucopus-dominated communities are also expected to maintain a higher frequency of those B. burgdorferi outer surface protein C (ospC) genotypes that this host species more efficiently transmits ('multiple niche polymorphism' hypothesis). Because some of these genotypes are human invasive, an additive increase in human disease risk is expected in species-poor settings. We assessed these theoretical predictions by comparing I. scapularis nymphal infection prevalence, density of infected nymphs and B. burgdorferi genotype diversity at sites on Block Island, RI, where P. leucopus dominates the mammalian host community, to species-diverse sites in northeastern Connecticut. We found no support for the dilution effect hypothesis; B. burgdorferi nymphal infection prevalence was similar between island and mainland and the density of B. burgdorferi infected nymphs was higher on the mainland, contrary to what is predicted by the dilution effect hypothesis. Evidence for the multiple niche polymorphism hypothesis was mixed: there was lower ospC genotype diversity at island than mainland sites, but no overrepresentation of genotypes with higher fitness in P. leucopus or that are more invasive in humans. We conclude that other mechanisms explain similar nymphal infection prevalence in both communities and that high ospC genotype diversity can be maintained in both species-poor and species-rich communities.

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Dataset Information

Using Landscape Analysis to Test Hypotheses about Drivers of Tick Abundance and Infection Prevalence with Borrelia burgdorferi.

Publications

Using Landscape Analysis to Test Hypotheses about Drivers of Tick Abundance and Infection Prevalence with Borrelia burgdorferi.

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