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Clinical Microbiology Reviews Mar 2020Increases in tick-borne disease prevalence and transmission are important public health issues. Efforts to control these emerging diseases are frustrated by the struggle... (Review)
Review
Increases in tick-borne disease prevalence and transmission are important public health issues. Efforts to control these emerging diseases are frustrated by the struggle to control tick populations and to detect and treat infections caused by the pathogens that they transmit. This review covers tick-borne infectious diseases of nonrickettsial bacterial, parasitic, and viral origins. While tick surveillance and tracking inform our understanding of the importance of the spread and ecology of ticks and help identify areas of risk for disease transmission, the vectors are not the focus of this document. Here, we emphasize the most significant pathogens that infect humans as well as the epidemiology, clinical features, diagnosis, and treatment of diseases that they cause. Although detection via molecular or immunological methods has improved, tick-borne diseases continue to remain underdiagnosed, making the scope of the problem difficult to assess. Our current understanding of the incidence of tick-borne diseases is discussed in this review. An awareness of the diseases that can be transmitted by ticks in specific locations is key to detection and selection of appropriate treatment. As tick-transmitted pathogens are discovered and emerge in new geographic regions, our ability to detect, describe, and understand the growing public health threat must also grow to meet the challenge.
Topics: Animals; Clinical Laboratory Techniques; Humans; Tick-Borne Diseases; Ticks
PubMed: 31896541
DOI: 10.1128/CMR.00083-18 -
Infection and Immunity Sep 2022Ticks are hematophagous ectoparasites capable of transmitting multiple human pathogens. Environmental changes have supported the expansion of ticks into new geographical... (Review)
Review
Ticks are hematophagous ectoparasites capable of transmitting multiple human pathogens. Environmental changes have supported the expansion of ticks into new geographical areas that have become the epicenters of tick-borne diseases (TBDs). The spotted fever group (SFG) of frequently infects ticks and causes tick-transmitted rickettsioses in areas of endemicity where ixodid ticks support host transmission during blood feeding. Ticks also serve as a reservoir for SFG . Among the members of SFG , R. rickettsii causes Rocky Mountain spotted fever (RMSF), the most lethal TBD in the United States. Cases of RMSF have been reported for over a century in association with several species of ticks in the United States. However, the isolation of R. rickettsii from ticks has decreased, and recent serological and epidemiological studies suggest that novel species of SFG are responsible for the increased number of cases of RMSF-like rickettsioses in the United States. Recent analyses of rickettsial genomes and advances in genetic and molecular studies of provided insights into the biology of with the identification of conserved and unique putative virulence genes involved in the rickettsial life cycle. Thus, understanding -host-tick interactions mediating successful disease transmission and pathogenesis for SFG rickettsiae remains an active area of research. This review summarizes recent advances in understanding how SFG species coopt and manipulate ticks and mammalian hosts to cause rickettsioses, with a particular emphasis on newly described or emerging SFG species.
Topics: Animals; Humans; Ixodidae; Mammals; Rickettsia; Rickettsia Infections; Rocky Mountain Spotted Fever; Ticks
PubMed: 35993770
DOI: 10.1128/iai.00621-21 -
Nature Communications Feb 2021Understanding ecological niches of major tick species and prevalent tick-borne pathogens is crucial for efficient surveillance and control of tick-borne diseases. Here...
Understanding ecological niches of major tick species and prevalent tick-borne pathogens is crucial for efficient surveillance and control of tick-borne diseases. Here we provide an up-to-date review on the spatial distributions of ticks and tick-borne pathogens in China. We map at the county level 124 tick species, 103 tick-borne agents, and human cases infected with 29 species (subspecies) of tick-borne pathogens that were reported in China during 1950-2018. Haemaphysalis longicornis is found to harbor the highest variety of tick-borne agents, followed by Ixodes persulcatus, Dermacentor nutalli and Rhipicephalus microplus. Using a machine learning algorithm, we assess ecoclimatic and socioenvironmental drivers for the distributions of 19 predominant vector ticks and two tick-borne pathogens associated with the highest disease burden. The model-predicted suitable habitats for the 19 tick species are 14‒476% larger in size than the geographic areas where these species were detected, indicating severe under-detection. Tick species harboring pathogens of imminent threats to public health should be prioritized for more active field surveillance.
Topics: Animals; China; Cluster Analysis; Geography; Incidence; Species Specificity; Tick Infestations; Tick-Borne Diseases; Ticks
PubMed: 33597544
DOI: 10.1038/s41467-021-21375-1 -
Revue Scientifique Et Technique... Apr 2015Ticks are prominent parasites and competent vectors of pathogens that affect both humans and animals. This review outlines and illustrates the main features of the... (Review)
Review
Ticks are prominent parasites and competent vectors of pathogens that affect both humans and animals. This review outlines and illustrates the main features of the morphology of ticks of the families Ixodidae and Argasidae, and summarises the basic components of their life cycles. It focuses mainly on development processes and mortality among tick populations so as to provide an overview of how they are regulated in nature and how pathogens can be transmitted under such a framework. The effects of the weather on these life cycles are reviewed. The author also examines how landscape structure and biotic factors, such as the presence and abundance of hosts, may shape the density of tick populations. The uncertainty inherent in dealing with the transmission of pathogens by ticks is highlighted; this results from the sometimes complex relationships among the vectors, the climate and the presence and density of host populations. The need to obtain reliable field estimations of such relationships before drawing conclusions about the effects of the isolated components of the system is stressed. A section is devoted to addressing the expected (and not yet totally understood) effects of trends in climate on the spread of ticks, and how these can be analysed and tracked.
Topics: Animals; Arachnid Vectors; Communicable Diseases; Feeding Behavior; Ticks
PubMed: 26470449
DOI: 10.20506/rst.34.1.2345 -
Frontiers in Cellular and Infection... 2018
Topics: Animals; Host-Pathogen Interactions; Humans; Immunity, Innate; Tick-Borne Diseases; Ticks; Transcriptome; Vaccines
PubMed: 29963500
DOI: 10.3389/fcimb.2018.00194 -
Frontiers in Immunology 2021
Topics: Animals; Host-Parasite Interactions; Humans; Immunity; Tick-Borne Diseases; Ticks; Vaccines
PubMed: 34868085
DOI: 10.3389/fimmu.2021.796558 -
Frontiers in Cellular and Infection... 2017Understanding host-pathogen-tick interactions remains a vitally important issue that might be better understood by basic research focused on each of the dyad interplays.... (Review)
Review
Understanding host-pathogen-tick interactions remains a vitally important issue that might be better understood by basic research focused on each of the dyad interplays. Pathogens gain access to either the vector or host during tick feeding when ticks are confronted with strong hemostatic, inflammatory and immune responses. A prominent example of this is the spp.-tick-vertebrate host relationship. spp. are intraerythrocytic apicomplexan organisms spread worldwide, with a complex life cycle. The presence of transovarial transmission in almost all the species is the main difference between their life cycle and that of other piroplasmida. With more than 100 species described so far, are the second most commonly found blood parasite of mammals after trypanosomes. The prevalence of spp. infection is increasing worldwide and is currently classified as an emerging zoonosis. and are the most frequent etiological agents associated with human babesiosis in North America and Europe, respectively. Although the -tick system has been extensively researched, the currently available prophylactic and control methods are not efficient, and chemotherapeutic treatment is limited. Studying the molecular changes induced by the presence of in the vector will not only elucidate the strategies used by the protozoa to overcome mechanical and immune barriers, but will also contribute toward the discovery of important tick molecules that have a role in vector capacity. This review provides an overview of the identified molecules involved in -tick interactions, with an emphasis on the fundamentally important ones for pathogen acquisition and transmission.
Topics: Animals; Antigens; Arthropod Proteins; Babesia; Babesiosis; Calreticulin; Disease Vectors; Glycoproteins; Host-Parasite Interactions; Salivary Glands; Tick-Borne Diseases; Ticks
PubMed: 29034218
DOI: 10.3389/fcimb.2017.00429 -
Parasite Immunology May 2021Ticks are haematophagous arthropods with unique molecular mechanisms for digesting host blood meal while acting as vectors for various pathogens of public health... (Review)
Review
Ticks are haematophagous arthropods with unique molecular mechanisms for digesting host blood meal while acting as vectors for various pathogens of public health significance. The tick's pharmacologically active saliva plays a fundamental role in modulating the host's immune system for several days to weeks, depending on the tick species. The vector tick has also developed sophisticated molecular mechanisms to serve as a competent vector for pathogens, including the spotted fever group (SFG) rickettsiae. Evidence is still inadequate concerning tick-rickettsiae-host interactions and saliva-assisted transmission of the pathogen to the mammalian host. Rickettsia parkeri, of the SFG rickettsia, can cause a milder version of Rocky Mountain spotted fever known as American Boutonneuse fever. The Gulf Coast tick (Amblyomma maculatum) often transmits this pathogenic rickettsia in the USA. This review discusses the knowledge gap concerning tick-rickettsiae-host interactions by highlighting the SFG rickettsia and the Am maculatum model system. Filling this knowledge gap will provide a better understanding of the tick-rickettsiae-host interactions in disease causation, which will be crucial for developing effective methods for preventing tick-borne diseases.
Topics: Animals; Antioxidants; Disease Models, Animal; Ixodidae; Microbiota; Oxidation-Reduction; Rickettsia; Rickettsia Infections; Saliva; Selenoproteins; Symbiosis; Ticks
PubMed: 33713348
DOI: 10.1111/pim.12830 -
Frontiers in Cellular and Infection... 2017Ticks and the pathogens they transmit constitute a growing burden for human and animal health worldwide. Vector competence is a component of vectorial capacity and... (Review)
Review
Ticks and the pathogens they transmit constitute a growing burden for human and animal health worldwide. Vector competence is a component of vectorial capacity and depends on genetic determinants affecting the ability of a vector to transmit a pathogen. These determinants affect traits such as tick-host-pathogen and susceptibility to pathogen infection. Therefore, the elucidation of the mechanisms involved in tick-pathogen interactions that affect vector competence is essential for the identification of molecular drivers for tick-borne diseases. In this review, we provide a comprehensive overview of tick-pathogen molecular interactions for bacteria, viruses, and protozoa affecting human and animal health. Additionally, the impact of tick microbiome on these interactions was considered. Results show that different pathogens evolved similar strategies such as manipulation of the immune response to infect vectors and facilitate multiplication and transmission. Furthermore, some of these strategies may be used by pathogens to infect both tick and mammalian hosts. Identification of interactions that promote tick survival, spread, and pathogen transmission provides the opportunity to disrupt these interactions and lead to a reduction in tick burden and the prevalence of tick-borne diseases. Targeting some of the similar mechanisms used by the pathogens for infection and transmission by ticks may assist in development of preventative strategies against multiple tick-borne diseases.
Topics: Animals; Arachnid Vectors; Disease Transmission, Infectious; Host-Pathogen Interactions; Humans; Tick-Borne Diseases; Ticks
PubMed: 28439499
DOI: 10.3389/fcimb.2017.00114 -
Frontiers in Cellular and Infection... 2019, the causative agent of the zoonotic disease tularemia, is characterized by high morbidity and mortality rates in over 190 different mammalian species, including... (Review)
Review
, the causative agent of the zoonotic disease tularemia, is characterized by high morbidity and mortality rates in over 190 different mammalian species, including humans. Based on its low infectious dose, multiple routes of infection, and ability to induce rapid and lethal disease, has been recognized as a severe public health threat-being designated as a NIH Category A Priority Pathogen and a CDC Tier 1 Select Agent. Despite concerns over its use as a bioweapon, most U.S. tularemia cases are tick-mediated and ticks are believed to be the major environmental reservoir for in the U.S. The American dog tick () has been reported to be the primary tick vector for , but the lone star tick () and other tick species also have been shown to harbor . This review highlights what is known, not known, and is debated, about the roles of different tick species as environmental reservoirs and transmission vectors for a variety of genotypes/strains.
Topics: Animals; Dermacentor; Disease Reservoirs; Dog Diseases; Dogs; Francisella tularensis; Genotype; Host-Pathogen Interactions; Humans; Ixodidae; Symbiosis; Tick-Borne Diseases; Ticks; Tularemia; United States
PubMed: 31139576
DOI: 10.3389/fcimb.2019.00146