Rickettsia hoogstraalii and a Rickettsiella from the Bat Tick Argas transgariepinus, in Namibia

First records of Secretargas transgariepinus (Argasidae) in Libya and Jordan: corrections of collection records and detection of microorganisms

The primarily bat-associated argasid tick, Secretargas transgariepinus (White, 1846), is a member of the Afrotropical and southern Palaearctic fauna. Probably because of its secretive life style, little is known about this species and records of its collection are scant. Based on morphological revisions of the available specimens, we report new Middle Eastern records for this tick species that had been misidentified as other bat-associated argasid taxa. These specimens are larvae from three localities, and represent the first records of S. transgariepinus from two countries: one larva from Sabratha (Libya) was collected from an unidentified bat species (possibly Eptesicus isabellinus), seven larvae from Azraq-Shishan (Jordan), and 78 larvae from Shamwari (Jordan) were all collected from Otonycteris hemprichii. Twenty larvae from Shamwari were also tested for the presence of both, viral or bacterial microorganisms by PCR. Three ticks were found to be infected with the Murid gammaherpesvirus 68 (MHV-68), one with Borrelia burgdorferi sensu lato, and four with a Rickettsia sp. closely related to Rickettsia slovaca. The findings represent a first evidence for the occurrence of these possible pathogens in S. transgariepinus.

Prevalence of tick-borne pathogens in ticks collected from the wild mountain ungulates mouflon and chamois in 4 regions of France

Ticks are major vectors of various pathogens of health importance, such as bacteria, viruses and parasites. The problems associated with ticks and vector-borne pathogens are increasing in mountain areas, particularly in connection with global climate change. We collected ticks (n = 2,081) from chamois and mouflon in 4 mountainous areas of France. We identified 6 tick species: Ixodes ricinus, Rhipicephalus bursa, Rh. sanguineus s.l., Haemaphysalis sulcata, H. punctata and Dermacentor marginatus. We observed a strong variation in tick species composition among the study sites, linked in particular to the climate of the sites. We then analysed 791 ticks for DNA of vector-borne pathogens: Babesia/Theileria spp., Borrelia burgdorferi s.l., Anaplasma phagocytophilum, A. marginale, A. ovis, and Rickettsia of the spotted fever group (SFG). Theileria ovis was detected only in Corsica in Rh. bursa. Babesia venatorum (2 sites), Borrelia burgdorferi s.l. (B. afzelii and B. garinii; 2 sites) and Anaplasma phagocytophilum (3 sites) were detected in I. ricinus. Anaplasma ovis was detected at one site in I. ricinus and Rh. sanguineus s.l. SFG Rickettsia were detected at all the study sites: R. monacensis and R. helvetica in I. ricinus at the 3 sites where this tick is present; R. massiliae in Rh. sanguineus s.l. (1 site); and R. hoogstraalii and Candidatus R. barbariae in Rh. bursa in Corsica. These results show that there is a risk of tick-borne diseases for humans and domestic and wild animals frequenting these mountain areas.

Molecular Detection of Rickettsia hoogstraalii in Hyalomma anatolicum and Haemaphysalis sulcata: Updated Knowledge on the Epidemiology of Tick-Borne Rickettsia hoogstraalii

Ticks are hematophagous ectoparasites that transmit pathogens to animals and humans. Updated knowledge regarding the global epidemiology of tick-borne Rickettsia hoogstraalii is dispersed, and its molecular detection and genetic characterization are missing in Pakistan. The current study objectives were to molecularly detect and genetically characterize Rickettsia species, especially R. hoogstraalii, in hard ticks infesting livestock in Pakistan, and to provide updated knowledge regarding their global epidemiology. Ticks were collected from livestock, including goats, sheep, and cattle, in six districts of Khyber Pakhtunkhwa (KP) Pakistan. Overall, 183 hosts were examined, of which 134 (73.2%), including goats (number = 39/54, 72.2%), sheep (23/40, 57.5%), and cattle (71/89, 80%) were infested by 823 ticks. The most prevalent tick species was Rhipicephalus microplus (number = 283, 34.3%), followed by Hyalomma anatolicum (223, 27.0%), Rhipicephalus turanicus (122, 14.8%), Haemaphysalis sulcata (104, 12.6%), Haemaphysalis montgomeryi (66, 8.0%), and Haemaphysalis bispinosa (25, 3.03%). A subset of 210 ticks was selected and screened for Rickettsia spp. using PCR-based amplification and subsequent sequencing of rickettsial gltA and ompB fragments. The overall occurrence rate of R. hoogstraalii was 4.3% (number = 9/210). The DNA of Rickettsia was detected in Hy. anatolicum (3/35, 8.5%) and Ha. sulcata (6/49, 12.2%). However, no rickettsial DNA was detected in Rh. microplus (35), Rh. turanicus (35), Ha. montgomeryi (42), and Ha. bispinosa (14). The gltA and ompB fragments showed 99-100% identity with R. hoogstraalii and clustered phylogenetically with the corresponding species from Pakistan, Italy, Georgia, and China. R. hoogstraalii was genetically characterized for the first time in Pakistan and Hy. anatolicum globally. Further studies should be encouraged to determine the role of ticks in the maintenance and transmission of R. hoogstraalii in different hosts.

Study of tick-borne zoonotic pathogens in questing and feeding ticks in Tenerife, Canary Islands, Spain

Ticks are vectors of many zoonotic pathogens of clinical relevance, including Anaplasma and Rickettsia species. Since few data about these tick-borne pathogens are available in the Canary Islands, the aim of the present study was to screen their presence in questing and feeding ticks on the island of Tenerife. A total of 81 ticks was removed from six hedgehogs, and eight ticks were collected from the grass. PCR assays for tick species identification based on the LSU rRNA gene, and detection of Anaplasma spp. and Rickettsia spp. by targeting the 16s rRNA and gltA gene, respectively, were carried out. Rhipicephalus sanguineus and Haemaphysalis formosensis tick species were identified, with Rickettsia hoogstraalii detected in H. formosensis. In addition, Rickettsia helvetica and one unidentified Rickettsia species were detected. The overall prevalence of Rickettsia in ticks was 12.2%, and none harbored Anaplasma sp. This work constitutes the first identification in the Canary Islands of pathogenic R. helvetica and the species of unknown pathogenicity R. hoogstraalii in questing ticks. The clinical relevance of the pathogens identified highlights the need for studies with increased sample size and locations, including potential hosts, as well as warning the population about the relevance of ticks as vectors.

Trends in Bacterial Pathogens of Bats: Global Distribution and Knowledge Gaps

Bats have received considerable recent attention for infectious disease research because of their potential to host and transmit viruses, including Ebola, Hendra, Nipah, and multiple coronaviruses. These pathogens are occasionally transmitted from bats to wildlife, livestock, and to humans, directly or through other bridging (intermediate) hosts. Due to their public health relevance, zoonotic viruses are a primary focus of research attention. In contrast, other emerging pathogens of bats, such as bacteria, are vastly understudied despite their ubiquity and diversity. Here, we describe the currently known host ranges and geographic distributional patterns of potentially zoonotic bacterial genera in bats, using published presence-absence data of pathogen occurrence. We identify apparent gaps in our understanding of the distribution of these pathogens on a global scale. The most frequently detected bacterial genera in bats are Bartonella, Leptospira, and Mycoplasma. However, a wide variety of other potentially zoonotic bacterial genera are also occasionally found in bats, such as Anaplasma, Brucella, Borrelia, Coxiella, Ehrlichia, Francisella, Neorickettsia, and Rickettsia. The bat families Phyllostomidae, Vespertilionidae, and Pteropodidae are most frequently reported as hosts of bacterial pathogens; however, the presence of at least one bacterial genus was confirmed in all 15 bat families tested. On a spatial scale, molecular diagnostics of samples from 58 countries and four overseas departments and island states (French Guiana, Mayotte, New Caledonia, and Réunion Island) reported testing for at least one bacterial pathogen in bats. We also identified geographical areas that have been mostly neglected during bacterial pathogen research in bats, such as the Afrotropical region and Southern Asia. Current knowledge on the distribution of potentially zoonotic bacterial genera in bats is strongly biased by research effort towards certain taxonomic groups and geographic regions. Identifying these biases can guide future surveillance efforts, contributing to a better understanding of the ecoepidemiology of zoonotic pathogens in bats.

Distribution and Prevalence of Anaplasmataceae, Rickettsiaceae and Coxiellaceae in African Ticks: A Systematic Review and Meta-Analysis

In Africa, ticks continue to be a major hindrance to the improvement of the livestock industry due to tick-borne pathogens that include Anaplasma, Ehrlichia, Rickettsia and Coxiella species. A systemic review and meta-analysis were conducted here and highlighted the distribution and prevalence of these tick-borne pathogens in African ticks. Relevant publications were searched in five electronic databases and selected using inclusion/exclusion criteria, resulting in 138 and 78 papers included in the qualitative and quantitative analysis, respectively. Most of the studies focused on Rickettsia africae (38 studies), followed by Ehrlichia ruminantium (27 studies), Coxiella burnetii (20 studies) and Anaplasma marginale (17 studies). A meta-analysis of proportions was performed using the random-effects model. The highest prevalence was obtained for Rickettsia spp. (18.39%; 95% CI: 14.23–22.85%), R. africae (13.47%; 95% CI: 2.76–28.69%), R. conorii (11.28%; 95% CI: 1.77–25.89%), A. marginale (12.75%; 95% CI: 4.06–24.35%), E. ruminantium (6.37%; 95% CI: 3.97–9.16%) and E. canis (4.3%; 95% CI: 0.04–12.66%). The prevalence of C. burnetii was low (0%; 95% CI: 0–0.25%), with higher prevalence for Coxiella spp. (27.02%; 95% CI: 10.83–46.03%) and Coxiella-like endosymbionts (70.47%; 95% CI: 27–99.82%). The effect of the tick genera, tick species, country and other variables were identified and highlighted the epidemiology of Rhipicephalus ticks in the heartwater; affinity of each Rickettsia species for different tick genera; dominant distribution of A. marginale, R. africae and Coxiella-like endosymbionts in ticks and a low distribution of C. burnetii in African hard ticks.

Phylogenetic Position of Haemaphysalis kashmirensis and Haemaphysalis cornupunctata, with Notes on Rickettsia spp

Despite high diversity in the Oriental region, ticks of the genus Haemaphysalis have been neglected regarding their genetic data and vector potential. This study aimed to genetically characterize three species of the genus Haemaphysalis: Haemaphysalis cornupunctata, Haemaphysalis kashmirensis, and Haemaphysalis montgomeryi infesting goats and sheep, and Rickettsia spp. associated with these tick species in the Hindu Kush Himalayan range of Pakistan. Altogether, 834 ticks were collected by examining 120 hosts including goats (64/120, 53.3%) and sheep (56/120, 46.6%), in which 86 (71.6%) hosts were found to be tick-infested. The morphologically identified ticks were subjected to DNA extraction and PCR for the amplification of partial 16S rDNA and cox fragments. Rickettsia spp. associated with the collected ticks were detected through the amplification of gltA, ompA and ompB partial fragments. The 16S rDNA of H. cornupunctata and H. montgomeryi showed a maximum identity of 100% with the sequences of the same species, whereas the 16S rDNA of H. kashmirensis showed the highest identity of 93-95% with Haemaphysalis sulcata. The cox sequence of H. montgomeryi displayed 100% identity with the same species. In comparison, the cox sequences of H. cornupunctata and H. kashmirensis showed maximum identities of 87.65-89.22% with Haemaphysalis punctata and 89.34% with H. sulcata, respectively. The gltA sequence of Rickettsia sp. from H. kashmirensis showed the highest identity of 97.89% with Rickettsia conorii subsp. raoultii, while the ompA and ompB fragments from the same DNA samples revealed 100% and 98.16% identity with Rickettsia sp. and "Candidatus Rickettsia longicornii", respectively. Another gltA sequence amplified from H. montgomeryi ticks showed 100% identity with Rickettsia hoogstraalii, while the attempts to amplify ompA and ompB for R. hoogstraalii were unsuccessful. In the phylogenetic tree, the 16S rDNA of H. cornupunctata clustered with the corresponding species while its cox clustered with H. punctata. Both 16S rDNA and cox sequences of H. kashmirensis clustered with H. sulcata. The gltA sequence of Rickettsia sp. was clustered individually in the spotted fever (SF) group of Rickettsia, while the gltA sequence of R. hoogstraalii was clustered with the same species in the transition group of Rickettsia. In the SF group, the rickettsial ompA and ompB sequence clustered with undetermined Rickettsia sp. and "Candidatus Rickettsia longicornii", respectively. This is the earliest study regarding the genetic characterization of H. kashmirensis. This study indicated that ticks belong to the genus Haemaphysalis have the potential of harboring and/or transmitting Rickettsia spp. in the region.

Unraveling the epidemiological relationship between ticks and rickettsial infection in Africa

Tick-borne rickettsioses are emerging and re-emerging diseases of public health concern caused by over 30 species of Rickettsia. Ticks are obligate hematophagous arthropods with over 700 species of Ixodid ticks known worldwide. The escalating geographical dispersal of tick vectors and concomitant increase in the incidences of tick-borne diseases have fueled interest in the ecology of tick-borne pathogens. This review focuses on aspects of the Rickettsia pathogen, including biology, taxonomy, phylogeny, genetic diversity, epidemiology of the disease, and the role of vertebrate host in the perpetuation of rickettsioses in Africa. Our review also highlights some of the species of Rickettsia that are responsible for disease, the role of tick vectors (both hard and soft ticks) and the species of Rickettsia associated with diverse tick species across the continent. Additionally, this article emphasizes the evolutionary perspective of rickettsiae perpetuation and the possible role of amplifying vertebrate host and other small mammals, domestic animals and wildlife in the epidemiology of Rickettsia species. We also specifically, discussed the role of avian population in the epidemiology of SFG rickettsiae. Furthermore, we highlighted tick-borne rickettsioses among travelers due to African tick-bite fever (ATBF) and the challenges to surveillance of rickettsial infection, and research on rickettsiology in Africa. Our review canvasses the need for more rickettsiologists of African origin based within the continent to further research towards understanding the biology, characterization, and species distribution, including the competent tick vectors involved in their transmission of rickettsiae across the continent in collaboration with established researchers in western countries. We further highlighted the need for proper funding to encourage research despite competing demands for resources across the various sectors. We finalize by discussing the similarities between rickettsial diseases around the world and which steps need to be taken to help foster our understanding on the eco-epidemiology of rickettsioses by bridging the gap between the growing epidemiological data and the molecular characterization of Rickettsia species.

Spotted Fever Group Rickettsia spp. Diversity in Ticks and the First Report of Rickettsia hoogstraalii in Romania

Simple Summary

Ticks are important parasites that feed on the blood of various host species, representing the most important arthropods transmitting diseases in Europe. Continuous changes in both tick distribution and abundance are related to multiple factors, including climate change. These changes have strong implications for both animal and human health; therefore, continuous surveillance of tickborne diseases is required for an appropriate evaluation of the potential risks faced by animals and humans in a given area. The spotted fever group Rickettsia comprises a large number of zoonotic agents with an increasing importance recognized in the last 30 years. The aim of this study was to evaluate these bacteria in ticks in Romania. Five Rickettsia species were identified in different tick species, with new pathogen–tick associations reported. Rickettsia hoogstraalii, one member of this group, was detected for the first time in Romania and in Rhipicephalus rossicus ticks. This species was first described in 2006 in Croatia, and its pathogenicity is not well known. In addition, the detection of R. raoultii and R. monacensis in unfed larvae of Haemaphysalis punctata reinforce the hypothesis of transmission of Rickettsia from female ticks to larvae; therefore the bite of larvae could pose a health risk.

Abstract

Tickborne bacterial pathogens have been described worldwide as risk factors for both animal and human health. Spotted fevers caused by Rickettsiae may cause non-specific symptoms, which make clinical diagnosis difficult. The aim of the current study was to evaluate and review the diversity of SFG Rickettsiae in ticks collected in 41 counties in Romania. A total of 2028 questing and engorged ticks collected in Romania belonging to five species were tested by PCR amplification of Rickettsia spp. gltA and 17-D gene fragments: Ixodes ricinus (n = 1128), Dermacentor marginatus (n = 507), D. reticulatus (n = 165), Rhipicephalus rossicus (n = 128) and Haemaphysalis punctata (n = 100). Five Rickettsia species were identified following DNA sequence analysis: R. helvetica, R. monacensis, R. slovaca, R. raoultii, and R. hoogstraalii. The most common species detected was R. monacensis. Moreover, R. hoogstraalii was detected for the first time in Romania and in R. rossicus ticks. The detection of R. raoultii and R. monacensis in questing larvae of Hae. punctata suggests the possible transovarial transmission of these Rickettsia species in ticks. The detection of R. hoogstraalii for the first time in Romania increases the reported SFG Rickettsia diversity in the country.

Rickettsia lusitaniae in Ornithodoros Porcinus Ticks, Zambia

Rickettsial pathogens are amongst the emerging and re-emerging vector-borne zoonoses of public health importance. Though traditionally considered to be transmitted by ixodid ticks, the role of argasid ticks as vectors of these pathogens is increasingly being recognized. While bat-feeding (Ornithodoros faini) and chicken-feeding (Argas walkerae) argasid ticks have been shown to harbor Rickettsia pathogens in Zambia, there are currently no reports of Rickettsia infection in southern Africa from warthog-feeding (Phacochoerus africanus) soft ticks, particularly Ornithodoros moubata and Ornithodoros porcinus. Our study sought to expand on the existing knowledge on the role of soft ticks in the epidemiology of Rickettsia species through screening for Rickettsia pathogens in warthog burrow-dwelling soft ticks from two national parks in Zambia. The tick species from which Rickettsia were detected in this study were identified as Ornithodoros porcinus, and an overall minimal Rickettsia infection rate of 19.8% (32/162) was observed. All of the sequenced Rickettsia were identified as Rickettsia lusitaniae based on nucleotide sequence similarity and phylogenetic analysis of the citrate synthase (gltA) and 17kDa common antigen (htrA) genes. Utilizing all of the gltA (n = 10) and htrA (n = 12) nucleotide sequences obtained in this study, BLAST analysis showed 100% nucleotide similarity to Rickettsia lusitaniae. Phylogenetic analysis revealed that all of the Zambian gltA and htrA gene sequences could be grouped with those of Rickettsia lusitaniae obtained in various parts of the world. Our data suggest that Rickettsia lusitaniae has a wider geographic and vector range, enhancing to our understanding of Rickettsia lusitaniae epidemiology in sub-Saharan Africa.

Argasid Ticks of Palearctic Bats: Distribution, Host Selection, and Zoonotic Importance

The soft ticks (Ixodida: Argasidae) are ectoparasites of terrestrial vertebrates with a wide geographic distribution, occurring on all continents. These ticks are obligate blood-feeders, most of them show high degrees of host-specialization and several species in arid and tropical regions are important parasites of livestock and men. Species commonly occurring on domestic animals and man are generally well-known, with many studies focusing on their ecology, distribution or vectorial role. However, wildlife-specialist soft ticks are less studied. Nearly half of all soft tick species are bat specialists, with five species (Carios vespertilionis, Chiropterargas boueti, Chiropterargas confusus, Reticulinasus salahi, and Secretargas transgariepinus) occurring in the Western Palearctic. There is no comprehensive study on the distribution, hosts or pathogens in these soft ticks, although most species were shown to carry several viral, bacterial, or protozoan pathogens and also to occasionally infest humans. Based on a literature survey and 1,120 distinct georeferenced records, we present here the geographical range, host selection and vectorial potential for bat-specialist soft ticks occurring in the Western Palearctic (chiefly Europe, North Africa, and the Middle East). Carios vespertilionis shows the largest distribution range and was found on most host species, being ubiquitous wherever crevice-roosting bats occur. All the other species were located only in areas with Mediterranean climate, with Ch. boueti, Chiropteraragas confusus, and R. salahi are missing entirely from Europe. These three species have a host spectrum of bats roosting primarily in caves, while S. transgariepinus and Ca. vespertilionis is feeding primarily on crevice-roosting bat species. All but one of these soft tick species are known to feed on humans and may be vectors of important disease agents (Rickettsia spp., Borrelia spp., Bartonella spp., Ehrlichia spp., Babesia spp., several nairo-, and flaviviruses). As several crevice-roosting bat species show a continuous adaptation to human-altered areas, with certain species becoming common city-dwellers in the Western Palearctic, the study of bat specialist soft ticks is also important from an epidemiologic point of view.

Detection of Rickettsia lusitaniae Among Ornithodoros sawaii Soft Ticks Collected From Japanese Murrelet Seabird Nest Material From Gugul Island, Republic of Korea

In a follow-up to the investigations of soft ticks identified from seabird nest soil and litter collected from coastal islands of the Republic of Korea (ROK), Ornithodoros sawaii and Ornithodoros capensis were assessed for the presence and identification of rickettsiae. Ticks collected from samples of 50-100 g of nest litter and soil from seabird nests were identified individually by morphological techniques, and species confirmed by sequencing of the mt-rrs gene. Subsequently, tick DNA preparations were screened for the presence of rickettsiae using a genus-specific nested PCR (nPCR) assay targeting the 17 kDa antigen gene. The amplicons from the 17 kDa assay and two additional nPCR assays targeting the gltA and ompB gene fragments were sequenced and used to identify the rickettsiae. A total of 134 soft ticks belonging to two species, O. sawaii Kitaoka & Suzuki 1973 (n = 125) and O. capensis Neumann 1901 (n = 9), were collected. Rickettsia lusitaniae DNA was detected and identified among O. sawaii ticks (n = 11, 8.8%) collected from nest litter and soil of the Japanese murrelet (Synthliboramphus wumizusume Temminck 1836) at Gugul Island along the western coastal area of the ROK. This study confirmed for the first time the presence of R. lusitaniae associated with O. sawaii collected from migratory seabird nests in the ROK.

Novel Genotypes of Nidicolous Argas Ticks and Their Associated Microorganisms From Spain

The knowledge of the distribution, richness and epidemiological importance of soft ticks of the genus Argas is incomplete. In Spain, five Argas species have been recorded, including three ornitophilic nidicolous ticks, but their associated microorganisms remain unknown. This study aimed to investigate ticks from bird nests and their microorganisms. Ticks were collected extensively from natural cavities and nest-boxes used by European rollers (Coracias garrulus) and little owls (Athene noctua) in Southeastern and Central Spain. Ticks were morphologically and genetically identified and corresponding DNA/RNA tick extracts were analyzed [individually (n = 150) or pooled (n = 43)] using specific PCR assays for bacteria (Anaplasmataceae, Bartonella, Borrelia, Coxiella/Rickettsiella, and Rickettsia spp.), viruses (Flaviviruses, Orthonairoviruses, and Phenuiviruses), and protozoa (Babesia/Theileria spp.). Six Argas genotypes were identified, of which only those of Argas reflexus (n = 8) were identified to the species level. Two other genotypes were closely related to each other and to Argas vulgaris (n = 83) and Argas polonicus (n = 33), respectively. These two species have not been previously reported from Western Europe. Two additional genotypes (n = 4) clustered with Argas persicus, previously reported in Spain. The remaining genotype (n = 22) showed low sequence identity with any Argas species, being most similar to the African Argas africolumbae. The microbiological screening revealed infection with a rickettsial strain belonging to Rickettsia fournieri and Candidatus Rickettsia vini group in 74.7% of ticks, mainly comprising ticks genetically related to A. vulgaris and A. polonicus. Other tick endosymbionts belonging to Coxiella, Francisella and Rickettsiella species were detected in ten, one and one tick pools, respectively. In addition, one Babesia genotype, closely related to avian Babesia species, was found in one tick pool. Lastly, Anaplasmataceae, Bartonella, Borrelia, and viruses were not detected. In conclusion, five novel Argas genotypes and their associated microorganisms with unproven pathogenicity are reported for Spain. The re-use of nests between and within years by different bird species appears to be ideal for the transmission of tick-borne microorganisms in cavity-nesting birds of semiarid areas. Further work should be performed to clarify the taxonomy and the potential role of soft Argas ticks and their microorganisms in the epidemiology of zoonoses.

Nuclear (18S-28S rRNA) and mitochondrial genome markers of Carios (Carios) vespertilionis (Argasidae) support Carios Latreille, 1796 as a lineage embedded in the Ornithodorinae: re-classification of the Carios sensu Klompen and Oliver (1993) clade into its respective subgenera

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).