Soft ticks are interesting ectoparasites due to their ecological habits and unique
blood-feeding biology. The wide-ranging nature of research into these parasites is
reflected in the diverse set of papers captured in this special issue. Fundamental
questions are addressed in the 9 articles included in this Research Topic that
focuses on ecology, tick-host interaction, host associations, geographic distribution, and
microbial endosymbionts.https://www.frontiersin.org/journals/veterinary-scienceam2023Veterinary Tropical Disease

Mans, Ben J. (Barend Johannes)

Munoz-Leal, Sebastian

Venzal, Jose M.

PubMed

Mans, Ben J.

Venzal, José M.

Muñoz-Leal, Sebastián

PubMed Central

Editorial: Soft ticks as parasites and vectors

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TYPE EditorialPUBLISHED 31 October 2022DOI 10.3389/fvets.2022.1037492OPEN ACCESSEDITED AND REVIEWED BYJosué Martínez-de la Puente,University of Granada, Spain*CORRESPONDENCEBen J. MansMansB@arc.agric.zaSPECIALTY SECTIONThis article was submitted toParasitology,a section of the journalFrontiers in Veterinary ScienceRECEIVED 05 September 2022ACCEPTED 29 September 2022PUBLISHED 31 October 2022CITATIONMans BJ, Venzal JM and Muñoz-Leal S(2022) Editorial: Soft ticks as parasitesand vectors. Front. Vet. Sci. 9:1037492.doi: 10.3389/fvets.2022.1037492COPYRIGHT© 2022 Mans, Venzal and Muñoz-Leal.This is an open-access articledistributed under the terms of theCreative Commons Attribution License(CC BY). The use, distribution orreproduction in other forums ispermitted, provided the originalauthor(s) and the copyright owner(s)are credited and that the originalpublication in this journal is cited, inaccordance with accepted academicpractice. No use, distribution orreproduction is permitted which doesnot comply with these terms.Editorial: Soft ticks as parasitesand vectorsBen J. Mans1,2,3*, José M. Venzal4 and Sebastián Muñoz-Leal51Epidemiology, Parasites and Vectors, Agricultural Research Council, Pretoria, South Africa,2Department of Veterinary Tropical Diseases, University of Pretoria, Pretoria, South Africa,3Department of Life and Consumer Sciences, University of South Africa, Pretoria, South Africa,4Centro Universitario Regional (CENUR) Litoral Norte, Universidad de la República, Salto, Uruguay,5Department of Animal Science, University of Concepcion, Chillán, ChileKEYWORDSargasids, ecology, bloodmeal, salivary glands, distributionEditorial on the Research TopicSoft ticks as parasites and vectorsSoft ticks are interesting ectoparasites due to their ecological habits and uniqueblood-feeding biology. The wide-ranging nature of research into these parasites isreflected in the diverse set of papers captured in this special issue. Fundamentalquestions are addressed in the 9 articles included in this Research Topic thatfocuses on ecology, tick-host interaction, host associations, geographic distribution, andmicrobial endosymbionts.Geographic dispersal of soft ticksAdult and nymphal soft ticks feed quickly and are therefore not extensively associatedwith their hosts. In addition, they are generally nest- or burrow-dwelling parasites.Therefore, how they disperse to new hosts and burrows is an interesting question totackle. The study by Rataud et al. investigated dispersal between yellow-legged gull (Larusmichahellis) nests for the soft tick Ornithodoros maritimus (also known as Alectorobiusmaritimus) using a capture-mark-recapture strategy within a natural bird populationduring the breeding season. Overall dispersal rates were low, confirming the strongendophilic nature of this tick species. This contrasted with previous results on therandom distribution of infectious organisms in this species that suggested extensivebetween-nest movement (1). The study considered the possibility that longer temporalscales of dispersal may be more relevant to argasid dispersal than short-term monitoringallows. The study certainly highlights great mysteries in soft tick biology that existregarding geographic and temporal dispersal, and how life stage, seasonality, nest- orburrow-occupancy, and tick-feeding status may impact this.Frontiers in Veterinary Science 01 frontiersin.orgMans et al. 10.3389/fvets.2022.1037492Host identification throughbloodmeal analysisThe ability of soft ticks to survive for extensive periodsof time is linked with their slow metabolism and capabilityto store their bloodmeal for prolonged periods in an intactand undigested form. The fact that soft ticks can feed multipletimes and that the previous bloodmeals survive feeding eventsin their guts offers the opportunity to utilize the bloodmeal toidentify past hosts. This biological particularity would greatlyexpand the ability to associate soft ticks with their naturalhosts, since the ticks are rarely collected on the host or dwellin burrows that harbor multiple vertebrate species, makinghost identification ambiguous. Two studies in this collectioninvestigated various methods to detect hosts by bloodmealanalysis of the soft tick Ornithodoros (Pavlovskyella) turicata.On the one hand, the study by Busselman et al. validatedthe use of PCR and Sanger sequencing in ticks artificially fedon chicken and pig blood and could detect host DNA upto 1,105 days after feeding. Based on these parameters, theyscreened 19 field-collected ticks from a cave in Austin, Texas,and showed evidence of the presence of raccoon, black vulture,Texas black rattlesnake, and human blood in bloodmeals. Onthe other hand, the study by Kim et al. investigated species-specific qPCR analysis using ticks fed on various host speciessuch as chicken, goat, and pig. According to their results, thespecific origin of bloodmeals could be detected beyond 330days post-feeding, throughmultiple molting events andmultiplespecies in one bloodmeal. The authors also investigated the useof stable isotope analyses for the identification of bloodmealorigin in ticks, but their results suggest that this approach is lesssensitive than qPCR. These studies highlighted the potential touse bloodmeal identification analyses as means to detect priorhosts and exploit the ability of soft ticks to retain intact hostblood across molts and feeding events. While the strategies used,such as host-specific qPCR and direct Sanger sequencing maylimit the ability to detect multiple hosts, future prospects suchas cloning and sequencing of amplicons or implementing next-generation amplicon sequencing approaches will expand theopportunity to uncover the array of hosts parasitized by soft ticksin their natural habitats.Domestic fowl as hosts of soft ticksMost argasids parasitize wild animals and their impact ondomestic animal or human health may be considered incidental,as found for the human that visited the cave frequented byO. (P.)turicata above (Busselman et al.). However, when infestationsof argasids are experienced in human homes or domesticanimal dwellings, the impact can be quite severe, especiallywhen infected with pathogenic agents. For instance, Argaspersicus parasitize poultry and has a worldwide distributionwith a preference for tropical regions, and is generally theexpected tick species when poultry dwellings are investigated.In the current collection, two studies geographically distantfrom each other investigated the infestation of poultry byargasids. Zahid et al. studied the infestation of domestic fowlin Khyber Pakhtunkhwa, Pakistan. From a large number ofticks collected from fowl dwellings (n = 7,219), the only tickfound was A. persicus, as confirmed by morphological andmolecular identification. The second study by López et al.from the Caribbean region of Colombia surprisingly foundthe exclusive infestation of fowl dwellings by Ornithodorospuertoricensis (also known as Alectorobius puertoricensis) asconfirmed by morphological and molecular identification. Thiswas the first association of this tick species with domestic fowl.Both studies highlight the importance of confirming which tickspecies parasitize domestic fowl in a given region since this willalso impact on risk assessment of zoonosis and the possibilitythat high infestations can spill over to nearby human dwellings.Birds as hosts of soft ticksPalomar et al. collected soft ticks in wild birds from Spain.In this study, the authors were unable to identify the ticks to thespecies level using current available morphological keys. Speciesrelationships were further investigated using mitochondrial 12Sand 16S ribosomal RNA and cytochrome oxidase 1 genes.Phylogenetic analysis of the 16S rRNA indicated species identitywith A. persicus and Argas reflexus, with at least two genotypesgrouping with a clade formed by Argas japonicus, Argaslagenoplastis, Argas polonicus, and Argas vulgaris and a genotypethat grouped with Argas africolumbae. The study pointed outthe important need for the development of accurate keys forthe genus Argas, given that this genus comprises 44 species withmany potential new Argas species, as found in the Palearcticregion. The study also detected Rickettsia, Coxiella, Francisella,and Rickettsiella species as well as a novel Babesia genotype,closely related to avian Babesia species. This highlights thepotential role of Argas species in transmitting zoonotic bacterialand piroplasmid agents.Bat-associated soft ticksSándor et al. investigated the associations betweensoft ticks and hosts, using mammals as study models.Five main tick species were identified, namely, Cariosvespertilionis, Chiropterargas boueti, Chiropterargas confusus,Reticulinasus salahi, and Secretargas transgariepinus. Exceptfor C. vespertilionis which showed the widest distribution, thedistribution maps for these ticks are data sparse and indicatea need for more studies on bats and their associated argasidspecies. The maps presented will serve as important referencepoints in this regard. Moreover, it is highlighted that mostFrontiers in Veterinary Science 02 frontiersin.orgMans et al. 10.3389/fvets.2022.1037492of these species would also parasitize humans and could beof zoonotic potential transmitting Rickettsia spp., Borreliaspp., Bartonella spp., Ehrlichia spp., Babesia spp., and severalnairo- and flaviviruses. Though this hypothesis still needsinvestigation. Integration of host association data shows littleevidence of host specificity. This study will definitely serve as animportant resource for argasids associated with Palearctic bats.Soft ticks in ChinaAnother meta-analysis of argasid ticks in China synthesizedcurrent knowledge on the species and associated pathogensfor this important but neglected region (Chen et al.). Up to 15argasid species were discussed including from the Argasinae:Argas assimilis, Argas beijingensis, Argas japonicus, A. persicus,Argas pusillus, A. reflexus, Argas robertsi, Argas sinensis,A. vulgaris, Ornithodoros lahorensis (also known as Alveonasuslahorensis); and from the Ornithodorinae: Argas vespertilionis(also known as Carios vespertilionis),Ornithodoros capensis (alsoknown as Alectorobius capensis), Ornithodoros (Ornithodoros)huajianensis, Ornithodoros (Pavlovskyella) papillipes, andOrnithodoros (Pavlovskyella) tartakovskyi. The study bringsto light old Chinese papers (1930s to 1960s) on soft ticks andhighlights that the diversity of argasid species in this regioncould be by far underestimated.Salivary gland transcriptomes of softticksLastly, the study by Reck et al. described the salivary glandtranscriptome of Ornithodoros (Pavlovskyella) brasiliensiselucidated by next-generation sequencing. This studycontributed a large number of genes from this speciesincluding secretory proteins and confirmed that these latter arehighly abundant in argasid salivary glands. This gene catalogwill be useful to identify toxins involved in toxicosis syndromescaused by this tick species in mammals.ConclusionsThis special issue highlighted the diversity of subject areasthat can be illuminated by the study of argasid species and theirbiology. It also represents a summary of some areas of interest incontemporary argasid biology and promises that further studyinto these research lines will expand in the future.Author contributionsBM: conceptualization and writing—original draft, andreview and editing. JV and SM-L: writing—review and editing.All authors read and approved the final manuscript.Conflict of interestThe authors declare that the research was conducted in theabsence of any commercial or financial relationships that couldbe construed as a potential conflict of interest.Publisher’s noteAll claims expressed in this article are solely those of theauthors and do not necessarily represent those of their affiliatedorganizations, or those of the publisher, the editors and thereviewers. Any product that may be evaluated in this article, orclaim that may be made by its manufacturer, is not guaranteedor endorsed by the publisher.References1. Dupraz M, Toty C, Devillers E, Blanchon T, Elguero E, Vittecoq M, et al.Population structure of the soft tick Ornithodoros maritimus and its associatedinfectious agents within a colony of its seabird host Larus michahellis. Int J ParasitolParasites Wildl. (2017) 6:122–30. doi: 10.1016/j.ijppaw.2017.05.001Frontiers in Veterinary Science 03 frontiersin.org

Editorial : Soft ticks as parasites and vectors

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Editorial : Soft ticks as parasites and vectors

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