Individual and environmental factors associated with the seroprevalence of Borrelia burgdorferi in Belgian farmers and veterinarians

Systematic Review and Meta-analysis of Lyme Disease Data and Seropositivity for Borrelia burgdorferi, China, 2005‒2020

Since its initial identification in 1986, Lyme disease has been clinically diagnosed in 29 provinces in China; however, national incidence data are lacking. To summarize Lyme disease seropositivity data among persons across China, we conducted a systematic literature review of Chinese- and English-language journal articles published during 2005‒2020. According to 72 estimates that measured IgG by using a diagnostic enzyme-linked assay (EIA) alone, the seropositivity point prevalence with a fixed-effects model was 9.1%. A more conservative 2-tier testing approach of EIA plus a confirmatory Western immunoblot (16 estimates) yielded seropositivity 1.8%. Seropositivity by EIA for high-risk exposure populations was 10.0% and for low-risk exposure populations was 4.5%; seropositivity was highest in the northeastern and western provinces. Our analysis confirms Lyme disease prevalence, measured by seropositivity, in many Chinese provinces and populations at risk. This information can be used to focus prevention measures in provinces where seropositivity is high.

Habitat suitability map of <em>Ixodes ricinus</em> tick in France using multi-criteria analysis

The tick Ixodes ricinus is widely distributed across Europe and is responsible for the transmission of several pathogens to humans and animals. In this study, we used a knowledge-based method to map variations in habitat suitability for I. ricinus ticks throughout continental France and Corsica. The multi-criteria decision analysis (MCDA) integrated four major biotic and abiotic factors known to influence tick populations: climate, land cover, altitude and the density of wild ungulates. For each factor, habitat suitability index (HSI) values were attributed to different locations based on knowledge regarding its impact on tick populations. For the MCDA, two methods of factor combination were tested, additive and multiplicative, both which were evaluated at the spatial scales of departments and local municipalities. The resulting habitat suitability maps (resolution=100x100 m) revealed that conditions are suitable for I. ricinus over most of France and Corsica. Particularly suitable habitats were located in central, north-eastern and south-western France, while less-suitable habitats were found in the Mediterranean and mountainous regions. To validate the approach, the HSI scores were compared to field data of I. ricinus nymph abundance. Regardless of scale, the correlation between abundance indicator and HSI score was stronger for the additive than for the multiplicative approach. Overall, this study demonstrates the value of MCDA for estimating habitat suitability maps for I. ricinus abundance, which could be especially useful in highlighting areas of the tick's distribution where preventive measures should be prioritised.

The evolving story of Borrelia burgdorferi sensu lato transmission in Europe

Beside mosquitoes, ticks are well-known vectors of different human pathogens. In the Northern Hemisphere, Lyme borreliosis (Eurasia, LB) or Lyme disease (North America, LD) is the most commonly occurring vector-borne infectious disease caused by bacteria of the genus Borrelia which are transmitted by hard ticks of the genus Ixodes. The reported incidence of LB in Europe is about 22.6 cases per 100,000 inhabitants annually with a broad range depending on the geographical area analyzed. However, the epidemiological data are largely incomplete, because LB is not notifiable in all European countries. Furthermore, not only differ reporting procedures between countries, there is also variation in case definitions and diagnostic procedures. Lyme borreliosis is caused by several species of the Borrelia (B.) burgdorferi sensu lato (s.l.) complex which are maintained in complex networks including ixodid ticks and different reservoir hosts. Vector and host influence each other and are affected by multiple factors including climate that have a major impact on their habitats and ecology. To classify factors that influence the risk of transmission of B. burgdorferi s.l. to their different vertebrate hosts as well as to humans, we briefly summarize the current knowledge about the pathogens including their astonishing ability to overcome various host immune responses, regarding the main vector in Europe Ixodes ricinus, and the disease caused by borreliae. The research shows, that a higher standardization of case definition, diagnostic procedures, and standardized, long-term surveillance systems across Europe is necessary to improve clinical and epidemiological data.

Occupational Lyme Disease: A Systematic Review and Meta-Analysis

Lyme disease (LD) can have significant consequences for the health of workers. The frequency of infection can be estimated by using prevalence and incidence data on antibodies against Borrelia Burgdoferi (BB). A systematic search of studies published in English between 2002 and 2021 and a meta-analysis were conducted in PubMed/Medline, Web of Science, Scopus, and Google Scholar databases. Out of a total of 1125 studies retrieved, 35 articles were included in the systematic review. Overall, in these studies, outdoor workers showed a 20.5% BB seroprevalence rate. Meta-analysis, performed on 15 studies (3932 subjects), revealed a significantly increased risk in outdoor activities (OR 1.93 95%CI 1.15–3.23), with medium-level heterogeneity (I² = 69.2%), and non-significant publication bias. The estimated OR in forestry and agricultural workers was 2.36 (CI95% 1.28; 4.34) in comparison with the controls, while a non-significant increase in risk (OR = 1.05, CI95% 0.28; 3.88) was found in the remaining categories of workers (veterinarians, animal breeders, soldiers). The estimated pooled risk was significantly higher in the studies published until 2010 (OR 3.03 95%CI 1.39–6.61), while in more recent studies the odds became non-significant (OR 1.08 95% CI 0.63–1.85). The promotion of awareness campaigns targeting outdoor workers in endemic areas, and the implementation of local programs aimed at controlling range expansion of vectors, are key strategies for protecting workers.

Shared Odds of Borrelia and Rabies Virus Exposure in Serbia

Lyme borreliosis (LB) is the most common tick-borne disease in Serbia and other European countries. Rabies is a fatal zoonosis distributed worldwide and is caused by the rabies virus. Professionals at risk of rabies-including veterinarians, hunters, communal service workers, and forestry workers-overlap with some professions at a higher risk of exposure to tick bites and tick-borne pathogen infections. We hypothesized that individuals identified by the public health system as at risk of rabies virus infection, and consequently vaccinated against rabies virus, also share a higher likelihood of Borrelia exposure. To test our hypothesis, a case-control study was carried out during 2019 in Serbia to determine the seroprevalence of anti-Borrelia antibodies in two case groups (individuals at risk and vaccinated against rabies virus) and a control group (individuals without risk of rabies). Individuals vaccinated against rabies following either "pre-exposure protocol" (PrEP, n = 58) or "post-exposure protocol" (PEP, n = 42) were considered as rabies risk groups and healthy blood donors (n = 30) as the control group. The results showed higher Borrelia seroprevalence in PrEP (17.2%; 10/58) and PEP (19.0%; 8/42) groups compared with the control group (6.67%; 2/30). Furthermore, odds ratio (OR) analysis showed that risk of rabies (in either the PrEP (OR = 2.91) or PEP (OR = 3.29) groups) is associated with increased odds of being seropositive to Borrelia. However, the difference in Borrelia seroprevalence between groups was not statistically significant (Chi-square (χ²) test p > 0.05). The shared odds of LB and rabies exposure found in this study suggest that, in countries where both diseases occur, the common citizen can be at risk of both diseases when in a risky habitat. These findings are important to guide physicians in targeting high-risk groups, and diagnose LB, and to guide decision-makers in targeting control and prevention measures for both infections in risk areas.

Association of Seropositivity to Borrelia burgdorferi With the Risk of Neuropsychiatric Disorders and Functional Decline in Older Adults: The Aging Multidisciplinary Investigation Study

Importance

Exposure to Borrelia burgdorferi (Bb) has been reported to be associated with certain neuropsychiatric disorders.

Objective

To establish the association between seropositivity to Bb and incidental neuropsychiatric disorders (eg, cognitive decline, incident dementia, and depressive symptoms) as well as functional decline.

Design, Setting, and Participants

This prospective, 6-year follow-up cohort study was conducted in a rural southwestern region of France and included 689 retired farmers 65 years or older randomly recruited from the Farmer Health Insurance System who agreed to submit a blood sample and were participants in the Aging Multidisciplinary Investigation study, an ongoing epidemiological prospective study of aging initiated in 2007. The data were analyzed from April to May 2019.

Exposures

Borrelia burgdorferi serology testing was performed in a 2-tiered approach. During the follow-up period, cognitive decline, incident dementia, depressive symptoms, and functional decline were repeatedly assessed.

Main Outcomes and Measures

Diagnosis of dementia relied on a 3-step procedure; cognitive decline was determined using the Mini-Mental State Examination and depressive symptomatology was assessed using the Center for Epidemiologic Studies Depression scale. For disability, scores on instrumental and basic activities of daily living were investigated.

Results

Of 689 participants, 432 (62.2%) were men and the mean (SD) age was 75.8 (6.4) years. The seroprevalence rate of Bb was 6.5%. At baseline, compared with Bb- participants, those who were Bb+ were older, predominantly men, and had lower depressive symptoms. No association between seropositivity and any of the studied outcomes (ie, cognitive decline, depressive symptoms, or functional decline) was found in the crude analysis and after adjusting for confounding variables. Regarding incident dementia, no increased risk was found among Bb+ participants (hazard ratio, 0.42; 95% CI, 0.1-1.17; adjusted for diverse confounders).

Conclusions and Relevance

To our knowledge, this is one of the few longitudinal studies exploring the risk of neuropsychiatric disorders and functional decline associated with exposure to Bb. Despite its limitations (eg, a lack of information if clinical manifestations of Lyme borreliosis existed, date of exposure, or treatment received), this study suggests that seropositivity to Bb is not a risk factor for incidental neuropsychiatric disorders and functional decline.

Active neuroborreliosis or inflammation: are the diagnostic guidelines at stake?

Neuroborreliosis can induce a variety of neurological syndromes: e.g., cranial neuritis, plexitis, radiculitis, meningitis, cerebellitis, … We report on five cases of patients with a diagnosis of neuroborreliosis based on clinical symptoms, serologic tests and MR imaging results. However, neither of them fulfils the diagnostic criteria for definite neuroborreliosis. Are the diagnostic criteria still valid or is there a need to revise them? Is our diagnosis correct? Are these cases post-Lyme auto-immune neuronal inflammation, and not due to still active spirochetal infection? Do we need to consider immunosuppressive therapy instead of third-generation cephalosporins?

Tick Bite Risk as a Socio-Spatial Representation—An Exploratory Study in Massif Central, France

Ticks are responsible for the largest number of transmissions of vector-borne diseases in the northern hemisphere, which makes the risk from tick bites a serious public health problem. Biological scientific research and prevention studies are important, but they have not focused on the population’s perception of tick bite risk, especially at a spatial level. This exploratory article sets out to study this point through an innovative methodology involving the collection of 133 mental maps associated with a semi-structured interview and a socio-demographic questionnaire collected in the Massif Central region, France. The results show a strong link between the representation of the tick bite risk and the representation of particular landscapes. Forests appear as dangerous for the population, especially in the traditional activities of family walking or hiking. This calls into question overly anxiogenic prevention approaches that neglect the impact on practices in risk-prone spaces. It accentuates the need for localized education measure to improve knowledge about tick biology and avoid stereotypical and unnecessary negative representations associated with the environment.

Geographical Features and Seroprevalence of Borrelia burgdorferi in Erzincan, Turkey

BACKGROUND

We aimed to determine the geographical features and seroprevalence of Borrelia burgdorferi in Erzincan, Turkey, which has a high tick population due to its geographical position and climatic conditions.

METHODS

From January to December 2014, 368 people living in Erzincan, northeastern Turkey were enrolled. B. burgdorferi IgG antibodies were investigated in the collected serum samples using the ELISA method in 2015. Positive and borderline results were confirmed using the Western Blot (WB) method.

RESULTS

Borrelia burgdorferi IgG positivity was found to be 4.1% by ELISA and 2.17% by WB. Of the seropositive people according to WB, 25% resided in areas within 2000m of rivers, 50% in areas with a slope of 0-5°, and 62.5% in areas with an altitude of lower than 1500 meters.

CONCLUSION

The seroprevalence of Lyme borreliosis was high in Erzincan, particularly among people engaged in animal husbandry in rural areas. In addition, the seroprevalence of Borrelia varied according to geographical features, increasing in areas with a lower slope and altitude.

Using volunteered observations to map human exposure to ticks

Lyme borreliosis (LB) is the most prevalent tick-borne disease in Europe and its incidence has steadily increased over the last two decades. In the Netherlands alone, more than 20,000 citizens are affected by LB each year. Because of this, two Dutch citizen science projects were started to monitor tick bites. Both projects have collected nearly 50,000 geo-located tick bite reports over the period 2006–2016. The number of tick bite reports per area unit is a proxy of tick bite risk. This risk can also be modelled as the result of the interaction of hazard (e.g. tick activity) and human exposure (e.g. outdoor recreational activities). Multiple studies have focused on quantifying tick hazard. However, quantifying human exposure is a harder task. In this work, we make a first step to map human exposure to ticks by combining tick bite reports with a tick hazard model. Our results show human exposure to tick bites in all forested areas of the Netherlands. This information could facilitate the cooperation between public health specialists and forest managers to create better mitigation campaigns for tick-borne diseases, and it could also support the design of improved plans for ecosystem management.

Seroprevalence of Borrelia burgdorferi in Belgian forestry workers and associated risk factors

Background

As forest is the preferred environment for ticks, forestry workers are exposed to tick bites and tick-borne diseases. We assessed the seroprevalence of anti-Borrelia burgdorferi (Bb) antibodies and investigated, using an integrated landscape approach, the individual and environmental factors associated with the seroprevalence of Bb in Belgian forestry workers, a high-risk group in Belgium.

Methods

A group of 310 Belgian forest workers was examined to assess the seroprevalence of anti-Borrelia IgG antibodies. Using principal component analysis and binary logistic regression, the joint effects of individual characteristics and environmental characteristics were examined.

Results

Sixty-seven of the 310 workers were seropositive for Lyme disease (LD), leading to a seroprevalence of 21.6%. The seroprevalence was higher among forest workers visiting forests more frequently (P = 0.003) or who reported over 100 tick bites (P-value < 0.001). The intensity of tick bites and the use of protection measures against tick bites have a positive impact on LD seroprevalence while the quantity of shadow from trees at ground level had a negative one.

Conclusions

This study showed that forest workers are a population at risk for LD and, by extension, at risk for various tick-borne diseases. In addition to the role of the environment, our results also showed the importance of considering exposure when predicting the risk of infection by Bb.