Reduction in human Lyme neuroborreliosis associated with a major epidemic among roe deer

Andersen, Nanna Skaarup; Skarphéðinsson, Sigurður; Knudtzen, Fredrikke Christie; Olesen, Carsten Riis; Jensen, Thøger Gorm; Jensen, Per Moestrup

doi:10.1016/j.ttbdis.2017.12.002

Cited by 7 publications

(6 citation statements)

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“…Within-season weather fluctuations have previously been suggested as a factor, influencing the amount of tick-human interaction [ 52 ] though, in our study, the overall difference between full seasons was investigated. The lack of difference coincides with data suggesting relatively stable seasonal distribution of reported neuroborreliosis cases over more extended periods [ 53 ], with the primary influence being access to roe deer, the main feeding and mating host [ 54 ].…”

Section: Discussionsupporting

confidence: 80%

Evaluation of factors influencing tick bites and tick-borne infections: a longitudinal study

et al. 2021

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Background Various tick-borne infections like borreliosis and rickettsiosis pose a health risk to humans in many parts of the world. We investigated seroprevalence of and seroconversion to Borrelia burgdorferi and Rickettsia spp. and relation to tick-bites, weather and clinical manifestations in Denmark. Methods Blood donors were enrolled at the Hospital of Southern Jutland in June–July with follow-up November–February of 2018 and 2019. Blood samples were collected, and a questionnaire regarding tick bites, potential exposures and symptoms was completed at each visit. Samples were tested for presence of IgM and IgG antibodies directed against B. burgdorferi and Rickettsia spp. using R. helvetica and R. felis as antigens. Data were examined for correlation between tick bites, serological results, potential exposures and symptoms. Results Two-hundred and fourteen (93 follow-ups) and 130 (38 follow-ups) blood donors were included in 2018 and 2019, respectively. The total borrelia seroconversion rate was 6.3% (CI 2.1–10.5), while the prevalence of IgM and IgG antibodies was 7.8% (CI 4.9–10.6) and 6.7% (CI 4–9.3), respectively. Seroconversion to Rickettsia spp. was detected in one participant. Tick bites and seroconversion were not significantly associated with the reported unspecific symptoms, but unspecific symptoms were common in the study population. There was no significant difference in number of tick bites or seroconversion/prevalence between seasons with highly alternating weather. Conclusions Results suggest that weather conditions in an individual year have a limited impact. Anti-Borrelia-antibodies do not seem to persist in serum for several years. Rickettsiosis is of limited concern in Denmark. Graphic abstract

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Section: Discussionsupporting

confidence: 80%

Evaluation of factors influencing tick bites and tick-borne infections: a longitudinal study

et al. 2021

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“…Some of the results are based on studies of deer exclosures on moorland or in forest, at a range of different deer densities and provide powerful evidence that areas with fewer deer have fewer ticks, and that both large and even very small fenced exclosures have significantly lower numbers of nymphs: fencing or reducing deer density by culling will both dramatically reduce tick abundance, equivalent to 86–96% control of questing nymphs [ 60 ]. On the island of Funen, Denmark, a major epizootic among roe deer seems to have drastically reduced tick abundance with the effect that the incidence of human neuroborreliosis declined significantly [ 21 ].…”

Section: Discussionmentioning

confidence: 99%

“…This tick species is a proven or putative vector of > 25 different viruses and microorganisms, which are known or highly suspected to be potential pathogens of humans [ 1 – 9 ]. In several European countries the numbers of diagnosed cases of tick-borne diseases transmitted by I. ricinus to humans have increased during the last two decades [ 10 – 19 ], but in some regions disease incidence appears not to have increased [ 20 ] or has even declined [ 21 ]. Tick-borne encephalitis (TBE) and Lyme borrelioses (LB, Lyme disease) are two disease complexes of major medical importance in the Palaearctic and Holarctic regions, respectively.…”

Section: Introductionmentioning

confidence: 99%

The importance of wildlife in the ecology and epidemiology of the TBE virus in Sweden: incidence of human TBE correlates with abundance of deer and hares

et al. 2018

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BackgroundTick-borne encephalitis (TBE) is one tick-transmitted disease where the human incidence has increased in some European regions during the last two decades. We aim to find the most important factors causing the increasing incidence of human TBE in Sweden. Based on a review of published data we presume that certain temperature-related variables and the population densities of transmission hosts, i.e. small mammals, and of primary tick maintenance hosts, i.e. cervids and lagomorphs, of the TBE virus vector Ixodes ricinus, are among the potentially most important factors affecting the TBE incidence. Therefore, we compare hunting data of the major tick maintenance hosts and two of their important predators, and four climatic variables with the annual numbers of human cases of neuroinvasive TBE. Data for six Swedish regions where human TBE incidence is high or has recently increased are examined by a time-series analysis. Results from the six regions are combined using a meta-analytical method.ResultsWith a one-year time lag, the roe deer (Capreolus capreolus), red deer (Cervus elaphus), mountain hare (Lepus timidus) and European hare (Lepus europaeus) showed positive covariance; the Eurasian elk (moose, Alces alces) and fallow deer (Dama dama) negative covariance; whereas the wild boar (Sus scrofa), lynx (Lynx lynx), red fox (Vulpes vulpes) and the four climate parameters showed no significant covariance with TBE incidence. All game species combined showed positive covariance.ConclusionsThe epidemiology of TBE varies with time and geography and depends on numerous factors, i.a. climate, virus genotypes, and densities of vectors, tick maintenance hosts and transmission hosts. This study suggests that the increased availability of deer to I. ricinus over large areas of potential tick habitats in southern Sweden increased the density and range of I. ricinus and created new TBEV foci, which resulted in increased incidence of human TBE. New foci may be established by TBE virus-infected birds, or by birds or migrating mammals infested with TBEV-infected ticks. Generally, persistence of TBE virus foci appears to require presence of transmission-competent small mammals, especially mice (Apodemus spp.) or bank voles (Myodes glareolus).Electronic supplementary materialThe online version of this article (10.1186/s13071-018-3057-4) contains supplementary material, which is available to authorized users.

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“…Sweden, the European roe deer is the most important blood meal host for ticks 11 . The number of ticks is linked to the number of roe deer in forest environments, and as a consequence to the number of LB cases 12 and TBE cases 13 . Therefore, the roe deer is important from a public health point of view.…”

Section: Introductionmentioning

confidence: 99%

Fivefold higher abundance of ticks (Acari: Ixodida) on the European roe deer (Capreolus capreolus L.) forest than field ecotypes

Opalińska

Wierzbicka

Asman

et al. 2021

Sci Rep

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The European roe deer (Capreolus capreolus) is the most common deer species in Europe. The species can be a reservoir of some tick-borne diseases but it is primarily recognized for its contribution as an amplifier host. In Central Europe, two roe deer ecotypes are living in adjacent areas: field and forest. We investigated differences in tick load and species composition on these two ecotypes. We collected ticks from 160 (80 the forest ecotype and 80 the field ecotype) roe deer culled in Wielkopolska Region (West-Central Poland). The most common was Ixodes ricinus (n = 1610; 99%) followed by Ixodes hexagonus (n = 22; 1%). The dominant life stage of the ticks was female. Prevalence was higher for forest roe deer. Mean number of ticks found on the forest ecotype was almost fivefold higher than on the field ecotype (3.75 ± 0.83 vs. 0.77 ± 0.20 ticks). The mean probability of tick occurrence was threefold higher in the forest (0.915 ± 0.050) than the field ecotype (0.279 ± 0.125). The most infested body parts of roe deer from both ecotypes were the neck and the head.

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Reduction in human Lyme neuroborreliosis associated with a major epidemic among roe deer

Cited by 7 publications

References 95 publications

Evaluation of factors influencing tick bites and tick-borne infections: a longitudinal study

Evaluation of factors influencing tick bites and tick-borne infections: a longitudinal study

The importance of wildlife in the ecology and epidemiology of the TBE virus in Sweden: incidence of human TBE correlates with abundance of deer and hares

Fivefold higher abundance of ticks (Acari: Ixodida) on the European roe deer (Capreolus capreolus L.) forest than field ecotypes

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