Candidatus Rickettsia Research Articles

Pathogenic Rickettsia, Anaplasma, and Ehrlichia in Rhipicephalus microplus ticks collected from cattle and laboratory hatched tick larvae.

The order Rickettsiales contains a group of vector-borne gram-negative obligate intracellular bacteria, which often cause human emerging infectious diseases and economic losses for dairy and meat industries. The purpose of this study is to investigate the distribution of the pathogens including Rickettsia spp., Anaplasma spp., and Ehrlichia spp. in the order Rickettsiales in ticks from Yueyang, a prefecture-level city of Hunan Province in Sothern China, and assess the potentiality of transovarial transmission of these rickettsial organisms. Ticks were collected from cattle in a farm in Yueyang City and the tick DNA was used as template to amplify the htrA, rrs, gltA, ompA and ompB genes of Rickettsia as well as rrs and groEL genes of Anaplasma and Ehrlichia. All ticks (465) collected were the cattle tick, Rhipicephalus microplus. PCR showed the minimum infection rate (MIR) was 1.5% (7/465) for Candidatus Rickettsia xinyangensis, 1.9% (9/465) for C. Anaplasma boleense, 1.3% (6/465) for Anaplasma platys, 0.6% (3/465) for A. marginale, and 1.17% (2/465) for each of A. bovis, Ehrlichia minasensis, and a non-classified Ehrlichia sp. A human pathogen, C. Rickettsia xinyangensis and A. platys were detected in 100% (3/3) and 33.3% (2/6) laboratory-hatched larval pools from infected females respectively. Our study revealed a diversity of pathogenic rickettsial species in R. microplus ticks from Hunan Province suggesting a threat to people and animals in China. This study also provided the first molecular evidence for the potential transovarial transmission of C. Rickettsia xinyangensis and A. platys in R. microplus, indicating that R. microplus may act as the host of these two pathogens.

Association of SFG Rickettsia massiliae and Candidatus Rickettsia shennongii with Different Hard Ticks Infesting Livestock Hosts.

Ixodid ticks are responsible for the transmission of various intracellular bacteria, such as the Rickettsia species. Little Information is available about the genetic characterization and epidemiology of Rickettsia spp. The current study was designed to assess the tick species infesting various livestock hosts and the associated Rickettsia spp. in Pakistan. Ticks were collected from different livestock hosts (equids, cattle, buffaloes, sheep, goats, and camels); morphologically identified; and screened for the genetic characterization of Rickettsia spp. by the amplification of partial fragments of the gltA, ompA and ompB genes. Altogether, 707 ticks were collected from 373 infested hosts out of 575 observed hosts. The infested hosts comprised 105 cattle, 71 buffaloes, 70 sheep, 60 goats, 34 camels, and 33 equids. The overall occurrence of Rickettsia spp. was 7.6% (25/330) in the tested ticks. Rickettsia DNA was detected in Rhipicephalus haemaphysaloides (9/50, 18.0%), followed by Rhipicephalus turanicus (13/99, 13.1%), Haemaphysalis cornupunctata (1/18, 5.5%), and Rhipicephalus microplus (2/49, 4.1%); however, no rickettsial DNA was detected in Hyalomma anatolicum (71), Hyalomma dromedarii (35), and Haemaphysalis sulcata (8). Two Rickettsia agents were identified based on partial gltA, ompA, and ompB DNA sequences. The Rickettsia species detected in Rh. haemaphysaloides, Rh. turanicus, and Rh. microplus showed 99-100% identity with Rickettsia sp. and Candidatus Rickettsia shennongii, and in the phylogenetic trees clustered with the corresponding Rickettsia spp. The Rickettsia species detected in Rh. haemaphysaloides, Rh. turanicus, Rh. microplus, and Ha. cornupunctata showed 100% identity with R. massiliae, and in the phylogenetic trees it was clustered with the same species. Candidatus R. shennongii was characterized for the first time in Rh. haemaphysaloides, Rh. turanicus, and Rh. microplus. The presence of SFG Rickettsia spp., including the human pathogen R. massiliae, indicates a zoonotic risk in the study region, thus stressing the need for regular surveillance.

Circulation of multiple Rickettsiales bacteria in ticks from Sichuan province, Southwest China

During 2021, 403 ticks including Haemaphysalis qinghaiensis, Ixodes ovatus, Ixodes acutitarsus, and Rhipicephalus microplus were collected from three sites (590, 310, and 576 km away from each other) in Sichuan Province, China. A total of nine Rickettsiales species were identified in them, including three Rickettsia spp., five Anaplasma spp., and one Ehrlichia sp. Anaplasma ovis and a novel Rickettsia sp. named “Candidatus Rickettsia liangshanensis” were characterized in I. ovatus ticks from Liangshan, with positive rates of 11.11% and 45.56%, respectively. Anaplasma capra (13.33%) and Anaplasma bovis (15.33%) were detected in H. qinghaiensis ticks from Maerkang. Phylogenetic analysis based on 16S rRNA, gltA, and groEL gene sequences indicated that the A. bovis strains were divided into two groups. Additionally, a novel Ehrlichia species named “Candidatus Ehrlichia maerkangensis” was identified. It is closely related to “Candidatus Ehrlichia zunyiensis” which was previously reported in Berylmys bowersi rats from Zunyi City, Southwest China. In R. microplus from Mianyang, “Candidatus Rickettsia jingxinensis” was detected with a high prevalence (92.99%). Notably, a variant of R. raoultii was identified in I. acutitarsus (33.33%). This may be the first Rickettsiales bacterium reported in I. acutitarsus. Our results reveal the remarkable biodiversity of Rickettsiales in this area. Some of these bacteria are human pathogens, indicating the potential exposure risk to local people.

A novel Rickettsia, Candidatus Rickettsia takensis, and the first record of Candidatus Rickettsia laoensis in Dermacentor from Northwestern Thailand

Three hundred and forty-four tick samples were collected from vegetation at Taksin Maharat National Park, Tak province, northwestern Thailand. They were morphologically identified and molecularly confirmed by 16S rRNA and COI genes as Dermacentor laothaiensis (n = 105), D. steini (n = 139), and D. auratus (n = 100). These ticks were examined for the spotted fever group rickettsiae (SFGRs) using PCR and DNA sequencing of six genes; 17-kDa, gltA, 16S rRNA, ompA, ompB, and sca4. Of these ticks, 6.10% (21/344) gave positive results for the presence of SFGRs. Phylogenetic analyses of the SFGRs clearly indicated that a novel genotype assigned as Candidatus Rickettsia takensis was detected in D. laothaiensis (19/105) and at lesser frequency in D. steini (1/139). Furthermore, Candidatus Rickettsia laoensis was also found at a low frequency in D. auratus (1/100), the first record in Thailand. Although, the pathogenicities of these SFGRs remain unknown, our findings suggest potential risks of SFGRs being transmitted via ticks near the border between Thailand and Myanmar, a gateway of daily migrations of local people and visitors both legal and illegal.

Detection of Rickettsia spp. and Anaplasma ovis in Melophagus ovinus from southern Xinjiang, China.

Melophagus ovinus is a hematophagous insect that is distributed worldwide and plays a crucial role in transmitting disease-causing pathogens. From June 2021 to March 2022, a total of 370 M. ovinus were collected from 11 sampling points in southern Xinjiang, China. The specimens were identified using morphological and molecular analyses. Rickettsia spp. and Anaplasma ovis were detected from all the samples using seven Rickettsia-specific genetic markers and the msp-4 gene of A. ovis. Approximately 11% of the M. ovinus specimens were positive for Rickettsia spp., and Candidatus Rickettsia barbariae was the most predominant species (35/41; 85.4%), while R. massiliae was least prevalent (6/41; 14.6%). Approximately 10.5% (39/370) of the M. ovinus specimens were positive for A. ovis of genotype III, which was co-detected with Candidatus R. barbariae in M. ovinus (3/370; 0.8%). To the best of our knowledge, this is the first report of the detection of R. massiliae and Candidatus R. barbariae in M. ovinus globally. The detection and control of insect-borne diseases originating from M. ovinus should be strengthened in southern Xinjiang, an area important to animal husbandry and production.

Applying next generation sequencing to detect tick-pathogens in Dermacentor nuttalli, Ixodes persulcatus, and Hyalomma asiaticum collected from Mongolia

Ticks and tick-borne diseases represent major threats to the public health of the Mongolian population, of which an estimated 26% live a traditional nomadic pastoralist lifestyle that puts them at increased risk for exposure. Ticks were collected by dragging and removal from livestock in Khentii, Selenge, Tuv, and Umnugovi aimags (provinces) during March-May 2020. Using next-generation sequencing (NGS) with confirmatory PCR and DNA sequencing, we sought to characterize the microbial species present in Dermacentor nuttalli (n = 98), Hyalomma asiaticum (n = 38), and Ixodes persulcatus (n = 72) tick pools. Rickettsia spp. were detected in 90.4% of tick pools, with Khentii, Selenge, and Tuv tick pools all having 100% pool positivity. Coxiella spp. were detected at an overall pool positivity rate of 60%, while Francisella spp. were detected in 20% of pools and Borrelia spp. detected in 13% of pools. Additional confirmatory testing for Rickettsia-positive pools demonstrated Rickettsia raoultii (n = 105), Candidatus Rickettsia tarasevichiae (n = 65) and R. slovaca/R. sibirica (n = 2), as well as the first report of Candidatus Rickettsia jingxinensis (n = 1) in Mongolia. For Coxiella spp. reads, most samples were identified as a Coxiella endosymbiont (n = 117), although Coxiella burnetii was detected in eight pools collected in Umnugovi. Borrelia species that were identified include Borrelia burgdorferi sensu lato (n = 3), B. garinii (n = 2), B. miyamotoi (n = 16), and B. afzelii (n = 3). All Francisella spp. reads were identified as Francisella endosymbiont species. Our findings emphasize the utility of NGS to provide baseline data across multiple tick-borne pathogen groups, which in turn can be used to inform health policy, determine regions for expanded surveillance, and guide risk mitigation strategies.

Molecular Detection of Anaplasma, Ehrlichia and Rickettsia Pathogens in Ticks Collected from Humans in the Republic of Korea, 2021.

Tick-borne pathogens (TBPs), transmitted by the bites of ticks, are of great medical and veterinary importance. They include bacteria, viruses, and protozoan parasites. To provide fundamental data on the risk of tick contact and public health strategies, we aimed to perform a molecular investigation on four tick-borne bacterial pathogens in ticks collected from humans across the Republic of Korea (ROK) in 2021. In total, 117 ticks were collected, including Haemaphysalis longicornis (56.4%), Amblyomma testudinarium (26.5%), Ixodes nipponensis (8.5%), H. flava (5.1%), and I. persulcatus (0.9%). Among the ticks, 20.5% (24/117) contained tick-borne bacterial pathogens, with infection rates of 17.9% for Rickettsia (Candidatus Rickettsia jingxinensis, R. tamurae, R. monacensis, and Candidatus Rickettsia tarasevichiae), 2.5% for Anaplasma (A. phagocytophilum, A. capra, and A. bovis), and 0.9% for Ehrlichia (Ehrlichia sp.). Additionally, the co-detection rate for R. monacensis and A. phagocytophilum was 0.9%. To our knowledge, this is the first report of A. capra and A. bovis detection in ticks collected from humans in the ROK. This study contributes to the understanding of the potential risk of tick contact and provides fundamental data for establishing a public health strategy for tick-borne disease management in the ROK.

Candidatus Rickettsia Vini DNA in Ticks Collected from Nest Burrows of the European Sand Martin (Riparia riparia) in Sweden.

Background: Birds can cross geographical and environmental barriers and thereby facilitate dispersal of tick-borne pathogens both as carriers of infected ticks and as reservoirs of pathogenic microorganisms. Ixodes lividus (Ixodida: Ixodidae) is an endophilic tick in the Palearctic region that is highly specialized on its host, the European sand martin Riparia riparia. The purpose of this study was to determine whether I. lividus ticks sampled from sand martin nests in Sweden carry vector-borne pathogens. Materials and Methods: Fed ticks were collected in the autumns of 2017 and 2019 from the nests of a European sand martin colony in southern Sweden. Ticks were identified morphologically to developmental stage and species and were tested for tick-borne pathogens using PCR-based methods. Results: None of the 41 ticks tested positive for five tick-borne pathogens including Borrelia spp., tick-borne encephalitis virus (TBEV), Neoehrlichia mikurensis, Anaplasma phagocytophilum, and Babesia spp. Thirty-seven (13 females, 23 nymphs and 1 larva) of the 41 ticks tested positive for the gltA gene of Rickettsia spp. The sequences of the 17 kDa and gltA genes were most closely related to Candidatus Rickettsia vini. Conclusion: Our study confirms other reports that I. lividus ticks associated with the European sand martin have high infection prevalence of Ca. R. vini.

Novel Genetic Lineages of Rickettsia helvetica Associated with Ixodes apronophorus and Ixodes trianguliceps Ticks.

Ixodes apronophorus is an insufficiently studied nidicolous tick species. For the first time, the prevalence and genetic diversity of Rickettsia spp. in Ixodes apronophorus, Ixodes persulcatus, and Ixodes trianguliceps ticks from their sympatric habitats in Western Siberia were investigated. Rickettsia helvetica was first identified in I. apronophorus with a prevalence exceeding 60%. "Candidatus Rickettsia tarasevichiae" dominated in I. persulcatus, whereas I. trianguliceps were infected with "Candidatus Rickettsia uralica", R. helvetica, and "Ca. R. tarasevichiae". For larvae collected from small mammals, a strong association was observed between tick species and rickettsiae species/sequence variants, indicating that co-feeding transmission in studied habitats is absent or its impact is insignificant. Phylogenetic analysis of all available R. helvetica sequences demonstrated the presence of four distinct genetic lineages. Most sequences from I. apronophorus belong to the unique lineage III, and single sequences cluster into the lineage I alongside sequences from European I. ricinus and Siberian I. persulcatus. Rickettsia helvetica sequences from I. trianguliceps, along with sequences from I. persulcatus from northwestern Russia, form lineage II. Other known R. helvetica sequences from I. persulcatus from the Far East group into the lineage IV. The obtained results demonstrated the high genetic variability of R. helvetica.

Molecular analysis of Rickettsia spp. and related tick-borne pathogens detected in dogs in Korea

Ticks are widespread in nature and serve as primary vectors for several tick-borne pathogens (TBPs). Ticks and TBPs cause considerable harm to humans and animals and have emerged as a major global public health concern. Domestic dogs are the major reservoirs of zoonotic agents owing to their constant interaction with humans. This study aimed to assess the prevalence and risk factors of canine TBPs, such as Rickettsiales, Coxiella burnetii, hepatozoa, and Borrelia spp., using molecular analyses. A total of 906 dogs were examined and 4 TBPs were identified: Anaplasma phagocytophilum (5; 0.6%), Hepatozoon canis (9; 1.0%), Candidatus Rickettsia longicornii (2; 0.2%), and Rickettsia tamurae (1; 0.1%). Ehrlichia spp., C. burnetii, and Borrelia spp. were not detected. To the best of our knowledge, this is the first study to perform a phylogenetic analysis of Candidatus R. longicornii and R. tamurae in dogs. These findings can help determine the potential public health risks by enhancing our understanding of the geographical and vector distributions of TBPs in Korea.

A novel Rickettsia species closely related to Rickettsia felis in Anopheles mosquitoes from Yingkou City, Northeast China.

Mosquitoes are generally recognized as the most important vector of many zoonotic pathogens. In this study, seven mosquitoes species were identified (Anopheles pullus, Anopheles sinensis, Anopheles lesteri, Anopheles kleini, Ochlerotatus dorsalis, Aedes koreicus and Culex inatomii) in samples collected from Yingkou City, Liaoning Province, Northeastern China. A novel Rickettsia species was detected in Anopheles sinensis (two of 71, 2.82%) and Anopheles pullus (one of 106, 0.94%) mosquitoes. Genetic analysis indicated that the rrs and ompB genes have highest 99.60% and 97.88%-98.14% identities to Rickettsia felis, an emerging human pathogen of global concern mainly harboured by fleas, mosquitoes and booklice. The gltA sequences of these strains have 99.72% of nucleotide similarity with Rickettsia endosymbiont of Medetera jacula. The groEL sequences have 98.37% similarity to both Rickettsia tillamookensis and Rickettsia australis. The htrA sequences have 98.77% similarity to Rickettsia lusitaniae. In the phylogenetic tree based on concatenated nucleotide sequences of rrs, gltA, groEL, ompB and htrA genes, these strains are closely related to R. felis. Herein, we name it 'Candidatus Rickettsia yingkouensis'. Its human pathogenicity to humans and animals is still to be determined.

Phylogenic position and low genomic diversity of 'Candidatus Rickettsia kotlanii' inferred by complete genome sequences of two Japanese isolates.

Many Rickettsia species of the spotted fever group (SFG) cause tick-borne diseases known as "spotted fever". One of the candidate SFG Rickettsia species is 'Candidatus Rickettsia kotlanii', which was first detected in Haemaphysalis concinna in Hungary in 2006. However, its precise phylogenetic position in the SFG is not clear because only single-gene sequence-based phylogenetic analyses were performed using very limited genes. Here, we present the complete genome sequences of two Japanese 'Ca. R. kotlanii' isolates, which differed only by a 135-bp insertion/deletion (InDel). Using these genomes and publicly available whole genome sequences of other Rickettsia species, the precise phylogenetic position of 'Ca. R. kotlanii' in Rickettsia was determined to be in a clade of the SFG. The phylogenetic relationships and average nucleotide identity of 'Ca. R. kotlanii' relative to the other species indicated that 'Ca. R. kotlanii' is an independent taxon in the SFG. Notably, although the genomes of the two isolates were almost identical, the isolates were obtained from different tick species in different regions and years, suggesting extremely low genomic diversity in 'Ca. R. kotlanii'. While the genome of 'Ca. R. kotlanii' is the smallest in the transitional group and SFG Rickettsia sequenced to date, we identified genes uniquely present or absent in 'Ca. R. kotlanii', but most were apparently degraded. Therefore, analyses of differences at the sequence (single nucleotide polymorphisms and small InDels) or gene expression level will be required to understand the functional or physiological features unique to 'Ca. R. kotlanii'. This article is protected by copyright. All rights reserved.

New insights into the impact of microbiome on horizontal and vertical transmission of a tick-borne pathogen

BackgroundThe impact of host skin microbiome on horizontal transmission of tick-borne pathogens , and of pathogen associated transstadial and transovarial changes in tick microbiome are largely unknown, but are important to control increasingly emerging tick-borne diseases worldwide.MethodsFocusing on a rickettsiosis pathogen, Rickettsia raoultii, we used R. raoultii-positive and R. raoultii-negative Dermacentor spp. tick colonies to study the involvement of skin microbiota in cutaneous infection with rickettsiae in laboratory mice, and the function of the tick microbiome on maintenance of rickettsiae through all tick developmental stages (eggs, larvae, nymphs, adults) over two generations.ResultsWe observed changes in the skin bacteria community, such as Chlamydia, not only associated with rickettsial colonization but also with tick feeding on skin. The diversity of skin microbiome differed between paired tick-bitten and un-bitten sites. For vertical transmission, significant differences in the tick microbiota between pathogenic rickettsia-positive and -negative tick chorts was observed across all developmental stages at least over two generations, which appeared to be a common pattern not only for R. raoultii but also for another pathogenic species, Candidatus Rickettsia tarasevichiae. More importantly, bacterial differences were complemented by functional shifts primed for genetic information processing during blood feeding. Specifically, the differences in tick microbiome gene repertoire between pathogenic Rickettsia-positive and -negative progenies were enriched in pathways associated with metabolism and hormone signals during vertical transmission.ConclusionsWe demonstrate that host skin microbiome might be a new factor determining the transmission of rickettsial pathogens through ticks. While pathogenic rickettsiae infect vertebrate hosts during blood-feeding by the tick, they may also manipulate the maturation of the tick through changing the functional potential of its microbiota over the tick’s life stages. The findings here might spur the development of new-generation control methods for ticks and tick-borne pathogens.BrauQCozpnNTXK3Qm2qXLRVideo

'Candidatus Rickettsia andeanae' and Probable Exclusion of Rickettsia parkeri in Ticks from Dogs in a Natural Area of the Pampa Biome in Brazil.

Spotted fever illness caused by the tick-borne pathogen Rickettsia parkeri has emerged in the Pampa biome in southern Brazil, where the tick Amblyomma tigrinum is implicated as the main vector. Because domestic dogs are commonly parasitized by A. tigrinum, this canid is also a suitable sentinel for R. parkeri-associated spotted fever. Herein, we investigate rickettsial infection in ticks, domestic dogs and small mammals in a natural reserve of the Pampa biome in southern Brazil. The ticks A. tigrinum, Amblyomma aureolatum and Rhipicephalus sanguineus were collected from dogs. Molecular analyses of ticks did not detect R. parkeri; however, at least 34% (21/61) of the A. tigrinum ticks were infected by the non-pathogenic agent 'Candidatus Rickettsia andeanae'. Serological analyses revealed that only 14% and 3% of 36 dogs and 34 small mammals, respectively, were exposed to rickettsial antigens. These results indicate that the study area is not endemic for R. parkeri rickettsiosis. We tabulated 10 studies that reported rickettsial infection in A. tigrinum populations from South America. There was a strong negative correlation between the infection rates by R. parkeri and 'Candidatus R. andeanae' in A. tigrinum populations. We propose that high infection rates by 'Candidatus R. andeanae' might promote the exclusion of R. parkeri from A. tigrinum populations. The mechanisms for such exclusion are yet to be elucidated.

Tick-borne pathogens in ticks from urban and suburban areas of north-western Spain: Importance of Ixodes frontalis harbouring zoonotic pathogens.

To identify the questing tick populations in urban and suburban areas from the city of Lugo (NW Spain), ticks were collected monthly by flagging. The presence of Borrelia spp., Rickettsia spp. and Anaplasma phagocytophilum also was determined by polymerase chain reaction (PCR) and sequence analysis. Overall, 342 questing ticks were collected; the tick abundance was higher in suburban (95.9%) than in urban areas (4.1%). Ixodes frontalis was the most abundant (86.5%); 88.5% were larvae, 11.1% nymphs and 0.3% adults. All development stages of I. ricinus (7.3%) and adults of Rhipicephalus sanguineus sensu lato (5.8%) and Dermacentor reticulatus (0.3%) were found. Rickettsia spp. (31.9%) was more prevalent than Borrelia spp. (2.7%); no ticks were positive to A. phagocytophilum. Six Rickettsia species were identified (R. slovaca, R. monacensis, R. massiliae, R. raoultii, R. sibirica subsp. mongolitimonae and R. aeschielmanii); Candidatus Rickettsia rioja and two novel Rickettsia species also were detected. In addition, Borrelia turdi (1.8%) and B. valaisiana (0.9%) were identified in Ixodes ticks. This is the first report of R. slovaca in R. sanguineus s.l. and of R. monacensis, R. raoultii, R. slovaca, R. sibirica subsp. mongolitimonae and Ca. R. rioja in I. frontalis. Since most of the pathogens detected are zoonotic, their presence in these areas may have implications for public health.

Ticks and Rickettsiae Associated with Wild Animals Sold in Bush Meat Markets in Cameroon.

Ticks are obligate blood-sucking parasites of wild animals and transmit many zoonotic microorganisms that can spread to domesticated animals and then to humans. In Cameroon, little is known about tick diversity among wildlife, especially for animals which are hunted for human consumption. Therefore, this survey was undertaken to investigate tick and Rickettsia species diversity parasitizing the wild animals sold in bush meat markets in Cameroon. In total, 686 ticks were collected and identified to the species level based on morphology, and some were genetically analyzed using the 16S rRNA gene. Eighteen tick species belonging to five genera were identified: Amblyomma spp. (Amblyomma compressum, Amblyomma flavomaculatum, and Amblyomma variegatum), Haemaphysalis spp. (Haemaphysalis camicasi, Haemaphysalis houyi, Haemaphysalis leachi, and Haemaphysalis parmata), Hyalomma spp. (Hyalomma nitidum, Hyalomma rufipes, and Hyalomma truncatum), Ixodes spp. (Ixodes rasus and Ixodes moreli), and Rhipicephalus spp. (Rhipicephalus guilhoni, Rhipicephalus moucheti, Rhipicephalus muhsamae, Rhipicephalus microplus, Rhipicephalus camicasi, and Rhipicephalus linnaei). In terms of Rickettsia important for public health, two Rickettsia spp., namely Rickettsia aeschlimannii and Rickettsia africae, were detected in Hyalomma spp. and Amblyomma spp., respectively. Distinct tick-pathogen patterns were present for divergent sequences of R. africae associated with exclusively A. variegatum vectors (type strain) versus vectors comprising A. compressum, A. flavomaculatum, and A. variegatum. This suggests possible effects of vector species population dynamics on pathogen population circulation dynamics. Furthermore, Candidatus Rickettsia africaustralis was detected for the first time in Cameroon in I. rasus. This study highlights the high diversity of ticks among wildlife sold in bush meat markets in Cameroon.

Human pathogens in ticks removed from humans in Hebei, China

Ticks are the hosts or vectors of many human pathogens, including viruses, bacteria and protozoa, and can transmit these causative agents to humans when feeding on human bodies. In this study, 26 ticks removed from humans in Hebei, China were tested for the presence of human-pathogenic microorganisms by Polymerase Chain Reaction (PCR) or Reversed Transcript PCR (RT-PCR). As a result, 11 ticks tested positive for at least one human pathogen. Specifically, four validated human pathogens, including Rickettsia raoultii, Candidatus Rickettsia tarasevichiae, Babesia venatorum, and Borrelia garinii, as well as Anaplasma ovis with zoonotic potential, were identified in Ixodes persulcatus, Dermacentor silvarum and Haemaphysalis concinna. Importantly, this is the first report of Anaplasma and Babesia species pathogenic to humans in Hebei province. Moreover, the co-infections, including double infection and quadruple infection were observed. In addition, Candidatus R. principis with unknown pathogenicity was identified in one tick, which may be the same species as Candidatus R. hongyuanensis based on the nucleotide identity and phylogenetic analysis. Concluding, four validated tick-borne pathogens and one with zoonotic potential were identified in ticks parasitizing humans, suggesting the potential high public health risk in the local human population.

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.

Changes in the Ixodes ricinus microbiome associated with artificial tick feeding.

Artificial tick feeding systems (ATFS) can be used to study tick biology and tick-pathogen interactions. Due to the long feeding duration of hard ticks, antibiotics are commonly added to the in vitro blood meal to prevent the blood from decaying. This may affect the ticks' microbiome, including mutualistic bacteria that play an important role in tick biology. This effect was examined by the consecutive feeding of Ixodes ricinus larvae, nymphs, and adults in vitro with and without the supplementation of gentamicin and in parallel on calves. DNA extracted from unfed females was analyzed by 16S rRNA sequencing. The abundance of Candidatus Midichloria mitochondrii, Rickettsia helvetica and Spiroplasma spp. was measured by qPCR in unfed larvae, nymphs, and adults. Larvae and nymphs fed on calves performed significantly better compared to both in vitro groups. Adults fed on blood supplemented with gentamicin and B vitamins had a higher detachment proportion and weight compared to the group fed with B vitamins but without gentamicin. The detachment proportion and weights of females did not differ significantly between ticks fed on calves and in vitro with gentamicin, but the fecundity was significantly higher in ticks fed on calves. 16S rRNA sequencing showed a higher microbiome species richness in ticks fed on calves compared to ticks fed in vitro. A shift in microbiome composition, with Ca. Midichloria mitochondrii as dominant species in females fed as juveniles on calves and R. helvetica as the most abundant species in females previously fed in vitro was observed. Females fed in vitro without gentamicin showed significant lower loads of Ca. M. mitochondrii compared to females fed in vitro with gentamicin and ticks fed on calves. Spiroplasma spp. were exclusively detected in female ticks fed on cattle by qPCR, but 16S rRNA sequencing results also showed a low abundance in in vitro females exposed to gentamicin. In conclusion, the employed feeding method and gentamicin supplementation affected the ticks' microbiome composition and fecundity. Since these changes may have an impact on tick biology and vector competence, they should be taken into account in studies employing ATFS.

Molecular Detection of Rickettsia and Other Bacteria in Ticks and Birds in an Urban Fragment of Tropical Dry Forest in Magdalena, Colombia.

Birds are important hosts in the life cycle of some species of ticks. In Colombia, there are few eco-epidemiological studies of tick-borne diseases; the existing ones have been focused on areas where unusual outbreaks have occurred. This study describes the identification of ticks collected from birds and vegetation, and the detection of bacteria in those ticks and in blood samples from birds in an urban fragment of tropical dry forest in the department of Magdalena, Colombia. Bird sampling was carried out monthly in 2021, and 367 birds, distributed among 41 species, were captured. All collected ticks were identified as Amblyomma sp. or Amblyomma dissimile. The presence of rickettsiae in ticks collected from birds was evaluated by molecular analysis of the gltA, ompA and sca1 genes. 16S rRNA meta-taxonomy was used to evaluate rickettsiae in ticks collected from vegetation and in blood samples from birds. The presence of the species "Candidatus Rickettsia colombianensi" was detected in ticks from birds. Bacteria of the family Rickettsiacea was the most abundant in ticks collected from vegetation. Bacteria of the families Staphylococcaceae, Comamonadaceae and Pseudomonadaceae were prevalent in the samples of blood from birds. Rickettsia spp. was also detected in low abundance in some of the bird blood samples.