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Sipari S, Kiljunen M, Nylund M, Kallio ER. Identifying breeding hosts of Ixodes ricinus ticks using stable isotope analysis of their larvae - Proof of concept. Ticks Tick Borne Dis 2024; 15:102252. [PMID: 37741086 DOI: 10.1016/j.ttbdis.2023.102252] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2023] [Revised: 08/28/2023] [Accepted: 09/08/2023] [Indexed: 09/25/2023]
Abstract
Ticks are important vectors of zoonotic pathogens. Ticks are parasites that are dependent on their hosts for blood meal to develop and reproduce. The abundance of ticks is dependent on the availability of suitable breeding hosts, often medium- and large-sized mammals. So far there has been a shortage of direct methods identifying the breeding hosts for the female ticks. In this study, we introduce a stable isotope analysis (SIA) method that enables us to identify the trophic group of the breeding host, i.e. the host on which the tick mother fed, by sampling larval ticks from the field. We established a reference database on the stable isotope (SI) values (δ13C and δ15N) of the blood of potential tick host species, and of larvae from Ixodes ricinus females, which have fed on known hosts. By comparing the SI values from field collected larval ticks to our reference data, we can determine their most likely host species group. Our results show that the isotopic signatures of I. ricinus tick larvae reflect the diet of the breeding host of the mother tick. SIA proved reliable in categorizing the breeding hosts of I. ricinus into two distinguishable trophic groups; herbivores and carni-omnivores. To our knowledge, this is the first time that stable isotope analyses have been applied to detect transovarial (i.e. over-generational) traces of a blood meal in ticks. The method provides an efficient, novel tool for directly identifying tick breeding hosts by sampling field collected larvae. Ixodes ricinus is the most important vector of TBPs (tick-borne pathogens) in Europe, and to predict and mitigate against the future risks that TBPs pose, it is crucial to have detailed knowledge on the hosts that support tick reproduction in nature.
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Affiliation(s)
- Saana Sipari
- Department of Biological and Environmental Sciences, University of Jyväskylä, Republic of Finland.
| | - Mikko Kiljunen
- Department of Biological and Environmental Sciences, University of Jyväskylä, Republic of Finland
| | - Minna Nylund
- Animal Health and Diagnostic Unit, Finnish Food Safety Authority, Republic of Finland
| | - Eva R Kallio
- Department of Biological and Environmental Sciences, University of Jyväskylä, Republic of Finland
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Eisen L. Rodent-targeted approaches to reduce acarological risk of human exposure to pathogen-infected Ixodes ticks. Ticks Tick Borne Dis 2023; 14:102119. [PMID: 36680999 PMCID: PMC10863499 DOI: 10.1016/j.ttbdis.2023.102119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Revised: 01/04/2023] [Accepted: 01/13/2023] [Indexed: 01/15/2023]
Abstract
In the United States, rodents serve as important hosts of medically important Ixodes ticks, including Ixodes scapularis and Ixodes pacificus, as well as reservoirs for human pathogens, including Anaplasma phagocytophilum, Borrelia burgdorferi sensu stricto (s.s.), and Babesia microti. Over the last four decades, different methods to disrupt enzootic transmission of these pathogens between tick vectors and rodent reservoirs have been developed and evaluated. Early work focused on self-application of topical acaricide by rodents to kill infesting ticks; this resulted in two different types of commercial products based on (i) delivery of permethrin to rodents via impregnated cotton offered as nesting material or (ii) application of fipronil to rodents via an impregnated wick as they navigate through a bait box to reach a food source. More recent work has focused on approaches where acaricides, antibiotics, or a vaccine against Bo. burgdorferi s.s. are delivered orally via rodent food baits. Of these, the oral vaccine and oral acaricide are nearest to commercialization. Other approaches in early stages of development include anti-tick vaccines for rodents and use of heritable genome editing to engineer white-footed mice (Peromyscus leucopus) that are refractory to Bo. burgdorferi s.s. In this review, I first outline general benefits and drawbacks of rodent-targeted tick and pathogen control methods, and then describe the empirical evidence for different approaches to impact enzootic pathogen transmission and acarological risk of human exposure to pathogen-infected Ixodes ticks. Rodent-targeted methods remain promising components of integrated tick management approaches but there are concerns about the robustness of the impact of existing rodent-targeted products across habitats and variable tick host communities, and in some cases also for the implementation cost in relation to what homeowners in Lyme disease endemic areas say they are willing to pay for tick control.
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Affiliation(s)
- Lars Eisen
- Division of Vector-Borne Diseases, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, 3156 Rampart Road, Fort Collins, CO 80521, United States.
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Kim HJ, Hamer GL, Hamer SA, Lopez JE, Teel PD. Identification of Host Bloodmeal Source in Ornithodoros turicata Dugès (Ixodida: Argasidae) Using DNA-Based and Stable Isotope-Based Techniques. Front Vet Sci 2021; 8:620441. [PMID: 33681326 PMCID: PMC7925843 DOI: 10.3389/fvets.2021.620441] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Accepted: 01/11/2021] [Indexed: 11/28/2022] Open
Abstract
The ecology and host feeding patterns of many soft ticks (Ixodida: Argasidae) remain poorly understood. To address soft tick-host feeding associations, we fed Ornithodoros turicata Dugès on multiple host species and evaluated quantitative PCR (qPCR) and stable isotope analyses to identify the vertebrate species used for the bloodmeal. The results showed that a qPCR with host-specific probes for the cytochrome b gene successfully identified bloodmeals from chicken (Gallus gallus L.), goat (Capra aegagrus hircus L), and swine (Sus scrofa domesticus) beyond 330 days post-feeding and through multiple molting. Also, qPCR-based bloodmeal analyses could detect multiple host species within individual ticks that fed upon more than one species. The stable isotope bloodmeal analyses were based on variation in the natural abundance of carbon (13C/12C) and nitrogen (15N/14N) isotopes in ticks fed on different hosts. When compared to reference isotope signatures, this method discerned unique δ13C and δ15N signatures in the ticks fed on each host taxa yet could not discern multiple host species from O. turicata that fed on more than one host species. Given the significance of soft tick-borne zoonoses and animal diseases, elucidating host feeding patterns from field-collected ticks using these methods may provide insight for an ecological basis to disease management.
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Affiliation(s)
- Hee J. Kim
- Department of Entomology, Texas A&M AgriLife Research, College Station, TX, United States
| | - Gabriel L. Hamer
- Department of Entomology, Texas A&M AgriLife Research, College Station, TX, United States
| | - Sarah A. Hamer
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX, United States
| | - Job E. Lopez
- Department of Pediatrics, Center for Tropical Medicine, Baylor College of Medicine, Houston, TX, United States
| | - Pete D. Teel
- Department of Entomology, Texas A&M AgriLife Research, College Station, TX, United States
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Busselman RE, Olson MF, Martinez V, Davila E, Briggs C, Eldridge DS, Higgins B, Bass B, Cropper TL, Casey TM, Edwards T, Teel PD, Hamer SA, Hamer GL. Host Bloodmeal Identification in Cave-Dwelling Ornithodoros turicata Dugès (Ixodida: Argasidae), Texas, USA. Front Vet Sci 2021; 8:639400. [PMID: 33659288 PMCID: PMC7917080 DOI: 10.3389/fvets.2021.639400] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Accepted: 01/20/2021] [Indexed: 01/12/2023] Open
Abstract
Tick-host bloodmeal associations are important factors when characterizing risks of associated pathogen transmission and applying appropriate management strategies. Despite their biological importance, comparatively little is known about soft tick (Argasidae) host associations in the United States compared to hard ticks (Ixodidae). In this study, we evaluated a PCR and direct Sanger sequencing method for identifying the bloodmeal hosts of soft ticks. We collected 381 cave-associated Ornithodoros turicata near San Antonio, Texas, USA, and also utilized eight colony-reared specimens fed artificially on known host blood sources over 1.5 years ago. We correctly identified the vertebrate host bloodmeals of two colony-reared ticks (chicken and pig) up to 1,105 days post-feeding, and identified bloodmeal hosts from 19 out of 168 field-collected soft ticks, including raccoon (78.9%), black vulture (10.5%), Texas black rattlesnake (5.3%), and human (5.3%). Our results confirm the retention of vertebrate blood DNA in soft ticks and advance the knowledge of argasid host associations in cave-dwelling O. turicata.
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Affiliation(s)
- Rachel E. Busselman
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX, United States
| | - Mark F. Olson
- Department of Entomology, Texas A&M AgriLife Research, College Station, TX, United States
| | - Viridiana Martinez
- Department of Ecology and Conservation Biology, Texas A&M University, College Station, TX, United States
| | - Edward Davila
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX, United States
| | - Cierra Briggs
- Department of Entomology, Texas A&M AgriLife Research, College Station, TX, United States
- Department of Entomology, Cornell University, Ithaca, NY, United States
| | - Devon S. Eldridge
- Department of Entomology, Texas A&M AgriLife Research, College Station, TX, United States
- Department of Ecology and Evolutionary Biology, University of Tennessee, Knoxville, Knoxville, TN, United States
| | - Bailee Higgins
- Department of Entomology, Texas A&M AgriLife Research, College Station, TX, United States
| | - Brittany Bass
- Department of Entomology, Texas A&M AgriLife Research, College Station, TX, United States
| | - Thomas L. Cropper
- 59th Medical Wing, Joint Base San Antonio, Lackland, San Antonio, TX, United States
| | - Theresa M. Casey
- 59th Medical Wing, Joint Base San Antonio, Lackland, San Antonio, TX, United States
| | - Theresa Edwards
- Texas Parks and Wildlife Department, Government Canyon State Natural Area, San Antonio, TX, United States
| | - Pete D. Teel
- Department of Entomology, Texas A&M AgriLife Research, College Station, TX, United States
| | - Sarah A. Hamer
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX, United States
| | - Gabriel L. Hamer
- Department of Entomology, Texas A&M AgriLife Research, College Station, TX, United States
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Modernizing the Toolkit for Arthropod Bloodmeal Identification. INSECTS 2021; 12:insects12010037. [PMID: 33418885 PMCID: PMC7825046 DOI: 10.3390/insects12010037] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Revised: 12/30/2020] [Accepted: 12/31/2020] [Indexed: 11/24/2022]
Abstract
Simple Summary The ability to identify the source of vertebrate blood in mosquitoes, ticks, and other blood-feeding arthropod vectors greatly enhances our knowledge of how vector-borne pathogens are spread. The source of the bloodmeal is identified by analyzing the remnants of blood remaining in the arthropod at the time of capture, though this is often fraught with challenges. This review provides a roadmap and guide for those considering modern techniques for arthropod bloodmeal identification with a focus on progress made in the field over the past decade. We highlight genome regions that can be used to identify the vertebrate source of arthropod bloodmeals as well as technological advances made in other fields that have introduced innovative new ways to identify vertebrate meal source based on unique properties of the DNA sequence, protein signatures, or residual molecules present in the blood. Additionally, engineering progress in miniaturization has led to a number of field-deployable technologies that bring the laboratory directly to the arthropods at the site of collection. Although many of these advancements have helped to address the technical challenges of the past, the challenge of successfully analyzing degraded DNA in bloodmeals remains to be solved. Abstract Understanding vertebrate–vector interactions is vitally important for understanding the transmission dynamics of arthropod-vectored pathogens and depends on the ability to accurately identify the vertebrate source of blood-engorged arthropods in field collections using molecular methods. A decade ago, molecular techniques being applied to arthropod blood meal identification were thoroughly reviewed, but there have been significant advancements in the techniques and technologies available since that time. This review highlights the available diagnostic markers in mitochondrial and nuclear DNA and discusses their benefits and shortcomings for use in molecular identification assays. Advances in real-time PCR, high resolution melting analysis, digital PCR, next generation sequencing, microsphere assays, mass spectrometry, and stable isotope analysis each offer novel approaches and advantages to bloodmeal analysis that have gained traction in the field. New, field-forward technologies and platforms have also come into use that offer promising solutions for point-of-care and remote field deployment for rapid bloodmeal source identification. Some of the lessons learned over the last decade, particularly in the fields of DNA barcoding and sequence analysis, are discussed. Though many advancements have been made, technical challenges remain concerning the prevention of sample degradation both by the arthropod before the sample has been obtained and during storage. This review provides a roadmap and guide for those considering modern techniques for arthropod bloodmeal identification and reviews how advances in molecular technology over the past decade have been applied in this unique biomedical context.
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Heylen D, Schmidt O, Dautel H, Gern L, Kampen H, Newton J, Gray J. Host identification in unfed ticks from stable isotope compositions (δ 13 C and δ 15 N). MEDICAL AND VETERINARY ENTOMOLOGY 2019; 33:360-366. [PMID: 30883848 DOI: 10.1111/mve.12372] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Revised: 01/21/2019] [Accepted: 02/08/2019] [Indexed: 06/09/2023]
Abstract
Determination of the ratios of natural stable isotopes (13 C/12 C and 15 N/14 N) in unfed Ixodes ricinus nymphs and adults, which, in their previous stage, fed on captive wild rodents (Apodemus sylvaticus and Myodes glareolus), wild birds (Parus major and Cyanistes caeruleus) or domestic ruminants (Ovis aries and Bos taurus), demonstrated that it is possible to identify each host category with confidence. First, the tick-blood spacing, which is the difference between values obtained from ticks and the blood of hosts that they had fed on in the previous stage, was consistent (152 spacings investigated from 15 host individuals in total). Second, potential confounding factors (tick age and sex) did not affect the discriminatory power of the isotope patterns, nor did different rearing conditions (room temperature vs. 4 °C) or the duration of development (maximum of 430 days). The findings that the tick-blood isotope spacings, across a diverse range of hosts, were similar and predictable, and that confounders had little or no effect on this, strongly support the usage of the isotope approach. Because each of the host categories has a different role in the population dynamics of I. ricinus and in tick-borne pathogen ecology, the method described here has great potential for the clarification of tick and tick-borne pathogen ecology in the field.
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Affiliation(s)
- D Heylen
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ, U.S.A
- Interuniversity Institute for Biostatistics and statistical Bioinformatics, Hasselt University, Diepenbeek, Belgium
- Department of Biology, University of Antwerp, Wilrijk, Belgium
| | - O Schmidt
- UCD School of Agriculture and Food Science, University College Dublin, Belfield, Dublin, Ireland
| | - H Dautel
- IS Insect Services GmbH, Berlin, Germany
| | - L Gern
- Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland
| | - H Kampen
- Friedrich-Loeffler-Institut, Greifswald-Insel Riems, Germany
| | - J Newton
- Scottish Universities Environmental Research Centre, East Kilbride, U.K
| | - J Gray
- UCD School of Biology and Environmental Science, University College Dublin, Belfield, Dublin, Ireland
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