Ixodes ticks maintain a large and diverse array of human pathogens in the enzootic cycle, including Borrelia burgdorferi and Babesia microti . Despite the poor ecological fitness of B. microti , ...babesiosis has recently emerged in areas endemic for Lyme disease. Studies in ticks, reservoir hosts, and humans indicate that coinfection with B. burgdorferi and B. microti is common, promotes transmission and emergence of B. microti in the enzootic cycle, and causes greater disease severity and duration in humans. These interdisciplinary studies may serve as a paradigm for the study of other vector-borne coinfections. Identifying ecological drivers of pathogen emergence and host factors that fuel disease severity in coinfected individuals will help guide the design of effective preventative and therapeutic strategies.
The incidence of tick-borne diseases has increased in recent decades and accounts for the majority of vectorborne disease cases in temperate areas of Europe, North America, and Asia. This emergence ...has been attributed to multiple and interactive drivers including changes in climate, land use, abundance of key hosts, and people's behaviors affecting the probability of human exposure to infected ticks. In this forum paper, we focus on how land use changes have shaped the eco-epidemiology of Ixodes scapularis-borne pathogens, in particular the Lyme disease spirochete Borrelia burgdorferi sensu stricto in the eastern United States. We use this as a model system, addressing other tick-borne disease systems as needed to illustrate patterns or processes. We first examine how land use interacts with abiotic conditions (microclimate) and biotic factors (e.g., host community composition) to influence the enzootic hazard, measured as the density of host-seeking I. scapularis nymphs infected with B. burgdorferi s.s. We then review the evidence of how specific landscape configuration, in particular forest fragmentation, influences the enzootic hazard and disease risk across spatial scales and urbanization levels. We emphasize the need for a dynamic understanding of landscapes based on tick and pathogen host movement and habitat use in relation to human resource provisioning. We propose a coupled natural-human systems framework for tick-borne diseases that accounts for the multiple interactions, nonlinearities and feedbacks in the system and conclude with a call for standardization of methodology and terminology to help integrate studies conducted at multiple scales.
Emerging and re‐emerging pathogens often stem from zoonotic origins, cycling between humans and animals, and are frequently vectored and maintained by hematophagous arthropod vectors. The efficiency ...by which these disease agents are successfully transmitted between vertebrate hosts is influenced by many factors, including the host on which a vector feeds. The Lyme disease bacterium Borrelia burgdorferi sensu lato has adapted to survive in complex host environments, vectored by Ixodes ticks, and maintained in multiple vertebrate hosts. The versatility of Lyme borreliae in disparate host milieus is a compelling platform to investigate mechanisms dictating pathogen transmission through complex networks of vertebrates and ticks. Squamata, one of the most diverse clade of extant reptiles, is comprised primarily of lizards, many of which are readily fed upon by Ixodes ticks. Yet, lizards are one of the least studied taxa at risk of contributing to the transmission and life cycle maintenance of Lyme borreliae. In this review, we summarize the current evidence, spanning from field surveillance to laboratory infection studies, supporting their contributions to Lyme borreliae circulation. We also summarize the current understanding of divergent lizard immune responses that may explain the underlying molecular mechanisms to confer Lyme spirochete survival in vertebrate hosts. This review offers a critical perspective on potential enzootic cycles existing between lizard‐tick‐Borrelia interactions and highlights the importance of an eco‐immunology lens for zoonotic pathogen transmission studies.
Lyme disease bacteria have adapted to survive diverse environments including ticks and a wide array of birds, small rodents, and lizards. Lizards are the least studied among these hosts. Here, we reviewed current paradigms of lizards' roles in the Lyme disease bacterial enzootic cycle. We further used lizards as a model to imply how the presence of a vertebrate host may mechanistically impact the transmission of a vector‐borne pathogen from molecular to ecological levels.
The ongoing COVID‐19 pandemic is a stark reminder of the devastating consequences of pathogen spillover from wildlife to human hosts, particularly in densely populated urban centers. Prevention of ...future zoonotic disease is contingent on informed surveillance for known and novel threats across diverse human–wildlife interfaces. Cities are a key venue for potential spillover events because of the presence of zoonotic pathogens transmitted by hosts and vectors living in close proximity to dense human settlements. Effectively identifying and managing zoonotic hazards requires understanding the socio‐ecological processes driving hazard distribution and pathogen prevalence in dynamic and heterogeneous urban landscapes. Despite increasing awareness of the human health impacts of zoonotic hazards, the integration of an eco‐epidemiological perspective into public health management plans remains limited. Here we discuss how landscape patterns, abiotic conditions, and biotic interactions influence zoonotic hazards across highly urbanized cities (HUCs) in temperate climates to promote their efficient and effective management by a multi‐sectoral coalition of public health stakeholders. We describe how to interpret both direct and indirect ecological processes, incorporate spatial scale, and evaluate networks of connectivity specific to different zoonotic hazards to promote biologically‐informed and targeted decision‐making. Using New York City, USA as a case study, we identify major zoonotic threats, apply knowledge of relevant ecological factors, and highlight opportunities and challenges for research and intervention. We aim to broaden the toolbox of urban public health stakeholders by providing ecologically‐informed, practical guidance for the evaluation and management of zoonotic hazards.
Effectively identifying and managing zoonotic hazards requires understanding the socio‐ecological processes driving hazard distribution and pathogen prevalence in dynamic and heterogeneous urban landscapes. Here we discuss how landscape patterns, abiotic conditions, and biotic interactions influence zoonotic hazards across highly urbanized cities (HUCs) in temperate climates to promote their efficient and effective management by a multi‐sectoral coalition of public health stakeholders. Using New York City, USA as a case study, we identify major zoonotic threats, apply knowledge of relevant ecological factors, and highlight opportunities and challenges for research and intervention.
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The nymph of the blacklegged tick (Ixodes scapularis), the primary North American vector of the causative agent of Lyme disease, must attach to a host by the end of its questing ...season in order to feed and subsequently molt into an adult. The proper timing of this behavior is critical both for the tick’s survival and for perpetuating the transmission of tick-borne pathogens. Questing also depletes limited nymphal lipid reserves and increases desiccation risk. Given this tradeoff, questing behavior and its environmental influences can be expressed in a dynamic state variable model. We develop what we believe to be the first such model for a tick, and investigate the influence of climate on nymph fitness predictions. We apply these results to the hypothesized inland migration of I. scapularis from island refugia, evaluating fitness under suboptimal questing strategies and uncertain environmental conditions.
Babesia microti and Borrelia burgdorferi, the respective causative agents of human babesiosis and Lyme disease, are maintained in their enzootic cycles by the blacklegged tick (Ixodes scapularis) and ...use the white-footed mouse (Peromyscus leucopus) as primary reservoir host. The geographic range of both pathogens has expanded in the United States, but the spread of babesiosis has lagged behind that of Lyme disease. Several studies have estimated the basic reproduction number (R0) for B. microti to be below the threshold for persistence (<1), a finding that is inconsistent with the persistence and geographic expansion of this pathogen. We tested the hypothesis that host coinfection with B. burgdorferi increases the likelihood of B. microti transmission and establishment in new areas. We fed I. scapularis larva on P. leucopus mice that had been infected in the laboratory with B. microti and/or B. burgdorferi. We observed that coinfection in mice increases the frequency of B. microti infected ticks. To identify the ecological variables that would increase the probability of B. microti establishment in the field, we integrated our laboratory data with field data on tick burden and feeding activity in an R0 model. Our model predicts that high prevalence of B. burgdorferi infected mice lowers the ecological threshold for B. microti establishment, especially at sites where larval burden on P. leucopus is lower and where larvae feed simultaneously or soon after nymphs infect mice, when most of the transmission enhancement due to coinfection occurs. Our studies suggest that B. burgdorferi contributes to the emergence and expansion of B. microti and provides a model to predict the ecological factors that are sufficient for emergence of B. microti in the wild.
Babesiosis Vannier, Edouard G; Diuk-Wasser, Maria A; Ben Mamoun, Choukri ...
Infectious disease clinics of North America,
06/2015, Letnik:
29, Številka:
2
Journal Article
Recenzirano
Odprti dostop
Babesiosis is caused by intraerythrocytic protozoan parasites that are transmitted by ticks, or less commonly through blood transfusion or transplacentally. Human babesiosis was first recognized in a ...splenectomized patient in Europe but most cases have been reported from the northeastern and upper midwestern United States in people with an intact spleen and no history of immune impairment. Cases are reported in Asia, Africa, Australia, Europe, and South America. Babesiosis shares many clinical features with malaria and can be fatal, particularly in the elderly and the immunocompromised.
Haemaphysalis longicornis, an invasive Ixodid tick, was recently reported in the eastern United States. The emergence of these ticks represents a potential threat for livestock, wildlife, and human ...health. We describe the distribution, host-seeking phenology, and host and habitat associations of these ticks on Staten Island, New York, a borough of New York City.
Abstract
Although the role of host movement in shaping infectious disease dynamics is widely acknowledged, methodological separation between animal movement and disease ecology has prevented ...researchers from leveraging empirical insights from movement data to advance landscape scale understanding of infectious disease risk. To address this knowledge gap, we examine how movement behaviour and resource utilization by white‐tailed deer (
Odocoileus virginianus
) determines blacklegged tick (
Ixodes scapularis
) distribution, which depend on deer for dispersal in a highly fragmented New York City borough. Multi‐scale hierarchical resource selection analysis and movement modelling provide insight into how deer's movements contribute to the risk landscape for human exposure to the Lyme disease vector–
I. scapularis
. We find deer select highly vegetated and accessible residential properties which support blacklegged tick survival. We conclude the distribution of tick‐borne disease risk results from the individual resource selection by deer across spatial scales in response to habitat fragmentation and anthropogenic disturbances.
Summary
Lyme borreliosis is caused by multiple species of the spirochete bacteria Borrelia burgdorferi sensu lato. The spirochetes are transmitted by ticks to vertebrate hosts, including small‐ and ...medium‐sized mammals, birds, reptiles, and humans. Strain‐to‐strain variation in host‐specific infectivity has been documented, but the molecular basis that drives this differentiation is still unclear. Spirochetes possess the ability to evade host immune responses and colonize host tissues to establish infection in vertebrate hosts. In turn, hosts have developed distinct levels of immune responses when invaded by different species/strains of Lyme borreliae. Similarly, the ability of Lyme borreliae to colonize host tissues varies among different spirochete species/strains. One potential mechanism that drives this strain‐to‐strain variation of immune evasion and colonization is the polymorphic outer surface proteins produced by Lyme borreliae. In this review, we summarize research on strain‐to‐strain variation in host competence and discuss the evidence that supports the role of spirochete‐produced protein polymorphisms in driving this variation in host specialization. Such information will provide greater insights into the adaptive mechanisms driving host and Lyme borreliae association, which will lead to the development of interventions to block pathogen spread and eventually reduce Lyme borreliosis health burden.
Lyme disease causing bacteria species are transmitted between ticks and different vertebrate hosts, including mammals, birds, and reptiles, and different bacteria species are associated with different hosts. Potential mechanisms driving these bacteria‐host associations include: strain‐to‐strain differences in the induced innate and adaptive immune response and bacteria protein variants that display differentially binding activity to cells.
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