Search

Bats and ticks are important sources of zoonotic pathogens. Therefore, understanding the diversity, distribution, and ecology of both groups is crucial for public health preparedness. Soft ticks (Argasidae) are a major group of ectoparasites commonly associated with bats. The multi-host life cycle of many argasids make them important vectors of pathogens. Over nine years (2011-2020), surveillance was undertaken to identify the ticks associated with common bats in Singapore. During this period, the bat tick Ornithodoros batuensis was detected within populations of two cave roosting bat species: Eonycteris spelaea and Penthetor lucasi. We examined the relationship between bat species, roosting behaviour, and probability of O. batuensis infestation. We also estimated the relationship between bat life history variables (body condition index, sex, and age) on the probability of infestation and tick count. This represents the first detection of O. batuensis and the genus Ornithodoros within Singapore. We also provide evidence of the continued persistence of Argas pusillus in Singapore with the second local record., Competing Interests: Declaration of competing interest We wish to confirm that there are no known conflicts of interest associated with this publication and there has been no significant financial support for this work that could have influenced its outcome., (Copyright © 2024 Elsevier B.V. All rights reserved.)

The soft ticks (Argasidae) are known vectors of human and animal pathogens around the globe and are relatively understudied. Our aim was to assess the presence of Rickettsia and Borrelia bacteria in Alectorobius kelleyi (Argasidae) parasitizing synanthropic bats in the highly urbanized northeastern United States. By collaborating with parasitologists, bat scientists and wildlife rehabilitators we were successful in obtaining A. kelleyi from five states. Since Argasid larvae will attach to their hosts for many days, most A. kelleyi examined (92%) were larvae collected from sick or injured big brown bats, Eptesicus fuscus, undergoing care at rehabilitation centers. In addition, we obtained adult A. kelleyi captured in residential living areas and trapped in attics. An in-depth analysis of a A. kelleyi found to be infected with a spotted fever group Rickettsia (SFGR) revealed a dual infection with a R. belli-like taxon (ancestral group) as well as an SFGR closely related to R. peacockii, likely the same previously found in A. kelleyi from Iowa and Kansas. We found that 36% of the A. kelleyi tested carried the SFGR. Furthermore, we detected a relapsing fever spirochete, likely Candidatus Borrelia johnsonii, in 25% of the A. kelleyi from Pennsylvania. While it is unclear if these bacteria constitute a health risk to either bats or humans, our study indicates that human exposure to ectoparasites infesting peridomestic wildlife should be considered in the epidemiology of tick-borne diseases., (Copyright © 2023. Published by Elsevier GmbH.)

Argasid systematics remains controversial with widespread adherence to the Hoogstraal (1985) classification scheme, even though it does not reflect evolutionary relationships and results in paraphyly for the main genera of soft ticks (Argasidae), namely Argas and Ornithodoros. The alternative classification scheme, proposed by Klompen and Oliver (1993), has problems of its own: most notably paraphyly of the subgenus Pavlovskyella and the controversial grouping together of the subgenera Alectorobius, Antricola, Carios, Chiropterargas, Nothoaspis, Parantricola, Reticulinasus and Subparmatus into the genus Carios. Recent phylogenetic analyses of 18S/28S rRNA sequences and mitochondrial genomes agree with the scheme of Klompen and Oliver (1993), with regard to the paraphyly of Pavlovskyella, placement of Alveonasus, Ogadenus, Proknekalia and Secretargas in the Argasinae and placement of Carios and Chiropterargas in the Ornithodorinae (Mans et al., 2019). The Carios clade and its constituent subgenera remain controversial, since the phylogenetic position of its type species Carios (Carios) vespertilionis Latreille, 1796 (formerly Argas vespertilionis) has not been determined with confidence. The current study aimed to resolve Carios sensu lato Klompen and Oliver, 1993, and Carios sensu stricto Hoogstraal, 1985, by determining and analysing phylogenetic nuclear and mitochondrial markers for C. (C.) vespertilionis. Both the nuclear and mitochondrial markers support placement of Carios s.s. within the subfamily Ornithodorinae, but to the exclusion of the clade that includes the 6 other subgenera that are part of Carios s.l. Klompen and Oliver (1993), namely Alectorobius, Antricola, Nothoaspis, Parantricola, Reticulinasus and Subparmatus. These 6 subgenera form a monophyletic clade that might be placed as new subgenera within the genus Alectorobius, or elevated to genera. Given the substantial differences in biology among these subgenera, we propose that these 6 subgenera be elevated to genera. Thus, we propose to modify the classification scheme of Mans et al. (2019) so that the subfamily Argasinae now has six genera, Alveonasus, Argas (subgenera Argas and Persicargas), Navis, Ogadenus, Proknekalia and Secretargas, and the subfamily Ornithodorinae has nine genera, Alectorobius, Antricola (subgenera Antricola and Parantricola), Carios, Chiropterargas, Nothoaspis, Ornithodoros (subgenera Microargas, Ornamentum, Ornithodoros, Pavlovskyella and Theriodoros), Otobius, Reticulinasus and Subparmatus (genera indicated in bold)., (Copyright © 2021 Elsevier GmbH. All rights reserved.)

A divergent strain of Rickettsia japonica was isolated from a Dew's Australian bat argasid tick, Argas (Carios) dewae, collected in southern Victoria, Australia and a full-genome analysis along with sequencing of 5 core gene fragments was undertaken. This isolate was designated Rickettsia japonica str. argasii (ATCC VR-1665, CSUR R179)., (Copyright © 2018 Elsevier GmbH. All rights reserved.)

The genus-level classification of soft ticks (Argasidae) is controversial. A previous phylogenetic analysis of morphological and developmental characters found that the genus Ornithodoros was paraphyletic and raised a new genus, Carios, for species previously in the genera Antricola, Argas, Ornithodoros, and Nothoaspis (Klompen and Oliver, 1993). Genetic analyses of soft ticks to date have been limited to 16S rRNA, which is not highly phylogenetically informative for this group. We sequenced the entire mitochondrial genomes of 7 species of soft ticks, and the partial mitochondrial genomes of a further 5 species of soft ticks. We used these sequences to test the genus-level classification of soft ticks. Our analyses strongly support a clade of Neotropical species (mostly bat-associated) within the subfamily Ornithodorinae. This clade, which we call Neotropical Ornithodorinae, has species from 2 genera, Antricola and Nothoaspis, and 2 subgenera, Ornithodoros (Alectorobius) and Ornithodoros (Subparmatus). We also addressed the phylogenetic position of Ornithodoros savignyi, the type species of the genus Ornithodoros. Our analysis strongly supports a clade consisting of Ornithodoros savignyi and 4 other Ornithodoros species: Or. brasiliensis, Or. moubata, Or. porcinus, and Or. rostratus. This clade, Ornithodoros sensu stricto, did not contain the Alectorobius and Subparmatus species, Or. (Alectorobius) fonsecai, Or. (Alectorobius) capensis, and Or. (Subparmatus) marinkellei, which in traditional classification schemes have been placed in the genus Ornithodoros. Our comparison of mitochondrial rRNA, nuclear rRNA, and mitochondrial genome analyses show that only mitochondrial genome sequences have the potential to resolve the controversial phylogenetic relationships within the major soft tick lineages, such as the taxonomic status of Carios sensu Klompen and Oliver (1993)., (Crown Copyright © 2013. Published by Elsevier GmbH. All rights reserved.)