Population structure and haplotype network analyses of Hyalomma anatolicum based on the large subunit ribosomal RNA (16S rRNA) gene.

Hyalomma anatolicum, an Anatolian hard tick is a well-recognized vector involved in the transmission of various pathogens to animals and humans. The present study elucidated the population structure and haplotype network of H. anatolicum based on the mitochondrial large subunit ribosomal RNA (16S rRNA) gene sequence. The population structure and haplotype network analysis of 75 sequences archived in the GenBank, including the 15 sequences generated herein, yielded 24 haplotypes. Haplotype 1 (Hap_1) was the predominant haplotype consisting of 45 sequences from India, China, Pakistan, Turkey, Egypt, Iraq, and Tajikistan. The complete haplotype network exhibited a stellate conformation, highlighting a recent population expansion. The overall dataset, together with the sequences corresponding to India, China, and Pakistan, showed a high haplotype (0.638 ± 0.065, 0.671 ± 0.103, 0.753 ± 0.099, and 0.854 ± 0.061, respectively) and low nucleotide (0.00407 ± 0.00090, 0.00525 ± 0.00196, 0.00680 ± 0.00233, and 0.00453 ± 0.00056, respectively) diversity, further emphasized a recent population expansion. The neutrality indices including Tajima's D, Fu and Li's D, and Fu and Li's F for the complete dataset (- 2.661, - 6.008, and - 5.649, respectively) as well as for the sequences from India (- 2.223, - 3.414, and - 3.567, respectively) were negative, suggesting deviation from neutrality and a recent population expansion. The present study provided novel insights into the population structure and haplotype networks of H. anatolicum based on the mitochondrial 16S rRNA gene, and the different tests inferred a low genetic differentiation and suggested a recent population expansion of this economically important tick species.

Interaction between spiders and ticks-ancient arthropod predatory behavior?

Ticks are ectoparasite vectors of pathogens affecting human and animal health worldwide. Rational integration of different control interventions including plant-derived repellents and acaricides, management of natural predators, and vaccines is required for innovative approaches to reduce the risks associated with ticks and tick-borne diseases. How tick populations are naturally controlled is always a question. Tick interactions with other arthropods including predators evolved from ancient times. In this study, Cretaceous (ca. 100 Mya) Burmese amber inclusions were identified as probably related to Compluriscutula vetulum (Acari: Ixodida: Ixodidae) tick larvae and spider silk. As illustrated in this study, ancient interactions between ticks and spiders may support arthropod predatory behavior as a natural control intervention. Rational integrative management of different tick control interventions including natural predators under a One Health perspective will contribute to effectively and sustainably reducing the risks associated with ticks and tick-borne diseases.

Investigation of Babesia spp. and Theileria spp. in ticks from Western China and identification of a novel genotype of Babesia caballi.

Babesia spp. and Theileria spp. are tick-borne protozoan parasites with veterinary importance. In China, epidemiological and genetic investigations on many Babesia and Theileria species were still absent in many areas and many tick species. From Aug 2021 to May 2023, 645 ticks were collected from the body surface of domestic animals (camels, goats, sheep, and cattle) using tweezers in seven counties in three provinces including Xinjiang (Qitai, Mulei, Hutubi, and Shihezi counties), Chongqing (Youyang and Yunyang counties), and Qinghai (Huangzhong county). Three tick species were morphologically and molecularly identified (334 Hyalomma asiaticum from Xinjiang, 245 Rhipicephalus microplus from Chongqing, and 66 Haemaphysalis qinghaiensis from Qinghai). A total of three Babesia species and two Theileria species were detected targeting the 18S gene. The COI and cytb sequences were also recovered from Babesia strains for further identification. In R. microplus from Chongqing, Babesia bigemina, the agent of bovine babesiosis, was detected. Notably, in H. asiaticum ticks from Xinjiang, a putative novel genotype of Babesia caballi was identified (0.90%, 3/334), whose COI and cytb genes have as low as 85.82% and 90.64-90.91% nucleotide identities to currently available sequences. It is noteworthy whether the sequence differences of its cytb contribute to the drug resistance of this variant due to the involvement of cytb in the drug resistance of Babesia. In addition, Theileria orientalis and Theileria annulata were detected in R. microplus from Chongqing (12.20%, 31/245) and H. asiaticum from Xinjiang (1.50%, 5/334), respectively. These results suggest that these protozoan parasites may be circulating in domestic animals in these areas. The pathogenicity of the novel genotype of B. caballi also warrants further investigation.

Pathogens associated with ticks (Acari: Ixodidae) and mammals in the Orinoquia region of Colombia: An approach to understanding vector-pathogen-host interactions.

The hard tick clade (Ixodidae) currently comprises 762 species worldwide (266 Prostriata and 496 Metastriata). A quarter of hard ticks are found in the Neotropical region, and 42 species have been documented in Colombia. Ixodidae species are important vectors of pathogens such as bacteria, helminths, protozoa, and viruses. In tick-borne diseases, vertebrate hosts perform an important role in the transmission, maintenance, and spread of pathogens. Colombia ranks sixth among countries with the highest mammal biodiversity, with a total of 548 species, where some of these species may be involved in pathogen transmission cycles with ticks as vectors. This research evaluated the presence of two genera of bacteria (Borrelia and Rickettsia) and the protozoan (Babesia) in ticks and mammals in the Orinoquia region of Colombia, establishing interaction networks. The information comes from 734 mammals (655 wild and 79 domestic), belonging to 59 species. Tick infestation (n = 1,805) was found with 14.85 % (n = 109) of the examined mammals and corresponds to nine tick species confirmed morphologically and molecularly. To detect pathogens 272 ticks were collected while feeding on 96 mammals; samples from 93 mammals were analyzed. The presence of borreliae from the relapsing fever group (RFG) and the Lyme disease group (LDG) were detected. Rickettsia spp. was detected in ticks and mammals, while Babesia bigemina was only detected in ticks. This research is the first to address the prevalence of zoonotic pathogens in domestic and wild mammals infested with hard ticks in the Department of Arauca, Colombia. Considering that reporting cases of infections with Babesia, Borrelia, and Rickettsia in Colombia is not mandatory, their impact on public health cannot be estimated. This highlights the importance of continuously detecting, confirming, and identifying these and other important pathogens within the "One Health" framework, as they have a significant economic and medical-veterinary impact globally.

Interspecies co-feeding transmission of Powassan virus between a native tick, Ixodes scapularis, and the invasive East Asian tick, Haemaphysalis longicornis.

BACKGROUND: Powassan virus, a North American tick-borne flavivirus, can cause severe neuroinvasive disease in humans. While Ixodes scapularis are the primary vectors of Powassan virus lineage II (POWV II), also known as deer tick virus, recent laboratory vector competence studies showed that other genera of ticks can horizontally and vertically transmit POWV II. One such tick is the Haemaphysalis longicornis, an invasive species from East Asia that recently established populations in the eastern USA and already shares overlapping geographic range with native vector species such as I. scapularis. Reports of invasive H. longicornis feeding concurrently with native I. scapularis on multiple sampled hosts highlight the potential for interspecies co-feeding transmission of POWV II. Given the absence of a clearly defined vertebrate reservoir host for POWV II, it is possible that this virus is sustained in transmission foci via nonviremic transmission between ticks co-feeding on the same vertebrate host. The objective of this study was to evaluate whether uninfected H. longicornis co-feeding in close proximity to POWV II-infected I. scapularis can acquire POWV independent of host viremia. METHODS: Using an in vivo tick transmission model, I. scapularis females infected with POWV II ("donors") were co-fed on mice with uninfected H. longicornis larvae and nymphs ("recipients"). The donor and recipient ticks were infested on mice in various sequences, and mouse infection status was monitored by temporal screening of blood for POWV II RNA via quantitative reverse transcription polymerase chain reaction (q-RT-PCR). RESULTS: The prevalence of POWV II RNA was highest in recipient H. longicornis that fed on viremic mice. However, nonviremic mice were also able to support co-feeding transmission of POWV, as demonstrated by the detection of viral RNA in multiple H. longicornis dispersed across different mice. Detection of viral RNA at the skin site of tick feeding but not at distal skin sites indicates that a localized skin infection facilitates transmission of POWV between donor and recipient ticks co-feeding in close proximity. CONCLUSIONS: This is the first report examining transmission of POWV between co-feeding ticks. Against the backdrop of multiple unknowns related to POWV ecology, findings from this study provide insight on possible mechanisms by which POWV could be maintained in nature.

The microbiota of Amblyomma americanum reflects known westward expansion.

Amblyomma americanum, a known vector of multiple tick-borne pathogens, has expanded its geographic distribution across the United States in the past decades. Tick microbiomes may play a role shaping their host's life history and vectorial capacity. Bacterial communities associated with A. americanum may reflect, or enable, geographic expansion and studying the microbiota will improve understanding of tick-borne disease ecology. We examined the microbiota structure of 189 adult ticks collected in four regions encompassing their historical and current geographic distribution. Both geographic region of origin and sex were significant predictors of alpha diversity. As in other tick models, within-sample diversity was low and uneven given the presence of dominant endosymbionts. Beta diversity analyses revealed that bacterial profiles of ticks of both sexes collected in the West were significantly different from those of the Historic range. Biomarkers were identified for all regions except the historical range. In addition, Bray-Curtis dissimilarities overall increased with distance between sites. Relative quantification of ecological processes showed that, for females and males, respectively, drift and dispersal limitation were the primary drivers of community assembly. Collectively, our findings highlight how microbiota structural variance discriminates the western-expanded populations of A. americanum ticks from the Historical range. Spatial autocorrelation, and particularly the detection of non-selective ecological processes, are indicative of geographic isolation. We also found that prevalence of Ehrlichia chaffeensis, E. ewingii, and Anaplasma phagocytophilum ranged from 3.40-5.11% and did not significantly differ by region. Rickettsia rickettsii was absent from our samples. Our conclusions demonstrate the value of synergistic analysis of biogeographic and microbial ecology data in investigating range expansion in A. americanum and potentially other tick vectors as well.

Diversity of Rickettsia species in collected ticks from Southeast Iran.

Rickettsia occurs worldwide and rickettsiosis is recognized as an emerging infection in several parts of the world. Ticks are reservoir hosts for pathogenic Rickettsia species in humans and domestic animals. Most pathogenic Rickettsia species belong to the spotted Fever Group (SFG). This study aimed to identify and diagnose tick fauna and investigate the prevalence of Rickettsia spp. in ticks collected from domestic animals and dogs in the rural regions of Kerman Province, Southeast Iran. In this study, tick species (fauna) were identified and 2100 ticks (350 pooled samples) from two genera and species including Rhipicephalus linnaei (1128) and Hyalomma deteritum (972) were tested to detect Rickettsia genus using Real-time PCR. The presence of the Rickettsia genus was observed in 24.9% (95%CI 20.28-29.52) of the pooled samples. Sequencing and phylogenetic analyses revealed the presence of Rickettsia aeschlimannii (48.98%), Rickettsia conorii israelensis (28.57%), Rickettsia sibirica (20.41%), and Rickettsia helvetica (2.04%) in the positive samples. The results showed a significant association between county variables and the following variables: tick spp. (p < 0.001), Rickettsia genus infection in ticks (p < 0.001) and Rickettsia spp. (p < 0.001). In addition, there was a significant association between tick species and host animals (dogs and domestic animals) (p < 0.001), Rickettsia spp infection in ticks (p < 0.001), and Rickettsia spp. (p < 0.001). This study indicates a high prevalence of Rickettsia spp. (SFG) in ticks of domestic animals and dogs in rural areas of Kerman Province. The health system should be informed of the possibility of rickettsiosis and the circulating species of Rickettsia in these areas.

Hard ticks (Ixodida: Ixodidae) in the Colombian Caribbean harbor the Jingmen tick virus: an emerging arbovirus of public health concern.

BACKGROUND: Ticks are obligate hematophagous ectoparasites involved in transmitting viruses of public health importance. The objective of this work was to identify the Jingmen tick virus in hard ticks from the Colombian Caribbean, an arbovirus of importance for public health. METHODS: Ticks were collected in rural areas of Córdoba and Cesar, Colombia. Taxonomic identification of ticks was carried out, and pools of 13 individuals were formed. RNA extraction was performed. Library preparation was performed with the MGIEasy kit, and next-generation sequencing (NGS) with MGI equipment. Bioinformatic analyses and taxonomic assignments were performed using the Galaxy platform, and phylogenetic analyses were done using IQ-TREE2. RESULTS: A total of 766 ticks were collected, of which 87.33% (669/766) were Rhipicephalus microplus, 5.4% (42/766) Dermacentor nitens, 4.2% (32/766) Rhipicephalus linnaei, and 3.0% (23/766) Amblyomma dissimile. Complete and partial segments 1, 2, 3, and 4 of Jingmen tick virus (JMTV) were detected in the metatranscriptome of the species R. microplus, D. nitens, and A. dissimile. The JMTVs detected are phylogenetically related to JMTVs detected in Aedes albopictus in France, JMTVs detected in R. microplus in Trinidad and Tobago, JMTVs in R. microplus and A. variegatum in the French Antilles, and JMTVs detected in R. microplus in Colombia. Interestingly, our sequences clustered closely with JMTV detected in humans from Kosovo. CONCLUSIONS: JMTV was detected in R. microplus, D. nitens, and A. dissimile. JMTV could pose a risk to humans. Therefore, it is vital to establish epidemiological surveillance measures to better understand the possible role of JMTV in tropical diseases.

Molecular screening and genetic diversity of tick-borne pathogens associated with dogs and livestock ticks in Egypt.

BACKGROUND: The Middle East and North Africa (MENA) offer optimal climatic conditions for tick reproduction and dispersal. Research on tick-borne pathogens in this region is scarce. Despite recent advances in the characterization and taxonomic explanation of various tick-borne illnesses affecting animals in Egypt, no comprehensive examination of TBP (tick-borne pathogen) statuses has been performed. Therefore, the present study aims to detect the prevalence of pathogens harbored by ticks in Egypt. METHODOLOGY/PRINCIPAL FINDINGS: A four-year PCR-based study was conducted to detect a wide range of tick-borne pathogens (TBPs) harbored by three economically important tick species in Egypt. Approximately 86.7% (902/1,040) of the investigated Hyalomma dromedarii ticks from camels were found positive with Candidatus Anaplasma camelii (18.8%), Ehrlichia ruminantium (16.5%), Rickettsia africae (12.6%), Theileria annulata (11.9%), Mycoplasma arginini (9.9%), Borrelia burgdorferi (7.7%), Spiroplasma-like endosymbiont (4.0%), Hepatozoon canis (2.4%), Coxiella burnetii (1.6%) and Leishmania infantum (1.3%). Double co-infections were recorded in 3.0% (27/902) of Hy. dromedarii ticks, triple co-infections (simultaneous infection of the tick by three pathogen species) were found in 9.6% (87/902) of Hy. dromedarii ticks, whereas multiple co-infections (simultaneous infection of the tick by ≥ four pathogen species) comprised 12% (108/902). Out of 1,435 investigated Rhipicephalus rutilus ticks collected from dogs and sheep, 816 (56.9%) ticks harbored Babesia canis vogeli (17.1%), Rickettsia conorii (16.2%), Ehrlichia canis (15.4%), H. canis (13.6%), Bo. burgdorferi (9.7%), L. infantum (8.4%), C. burnetii (7.3%) and Trypanosoma evansi (6.6%) in dogs, and 242 (16.9%) ticks harbored Theileria lestoquardi (21.6%), Theileria ovis (20.0%) and Eh. ruminantium (0.3%) in sheep. Double, triple, and multiple co-infections represented 11% (90/816), 7.6% (62/816), and 10.3% (84/816), respectively in Rh. rutilus from dogs, whereas double and triple co-infections represented 30.2% (73/242) and 2.1% (5/242), respectively in Rh. rutilus from sheep. Approximately 92.5% (1,355/1,465) of Rhipicephalus annulatus ticks of cattle carried a burden of Anaplasma marginale (21.3%), Babesia bigemina (18.2%), Babesia bovis (14.0%), Borrelia theleri (12.8%), R. africae (12.4%), Th. annulata (8.7%), Bo. burgdorferi (2.7%), and Eh. ruminantium (2.5%). Double, triple, and multiple co-infections represented 1.8% (25/1,355), 11.5% (156/1,355), and 12.9% (175/1,355), respectively. The detected pathogens' sequences had 98.76-100% similarity to the available database with genetic divergence ranged between 0.0001 to 0.0009% to closest sequences from other African, Asian, and European countries. Phylogenetic analysis revealed close similarities between the detected pathogens and other isolates mostly from African and Asian countries. CONCLUSIONS/SIGNIFICANCE: Continuous PCR-detection of pathogens transmitted by ticks is necessary to overcome the consequences of these infection to the hosts. More restrictions should be applied from the Egyptian authorities on animal importations to limit the emergence and re-emergence of tick-borne pathogens in the country. This is the first in-depth investigation of TBPs in Egypt.

Effect of Silencing subolesin and enolase impairs gene expression, engorgement and reproduction in Haemaphysalis longicornis (Acari: Ixodidae) ticks.

IMPORTANCE: Haemaphysalis longicornis is an obligate blood-sucking ectoparasite that has gained attention due its role of transmitting medically and veterinary significant pathogens and it is the most common tick species in Republic of Korea. The preferred strategy for controlling ticks is a multi-antigenic vaccination. Testing the efficiency of a combination antigen is a promising method for creating a tick vaccine. OBJECTIVE: The aim of the current research was to analyze the role of subolesin and enolase in feeding and reproduction of H. longicornis by gene silencing. METHODS: In this study, we used RNA interference to silence salivary enolase and subolesin in H. longicornis. Unfed female ticks injected with double-stranded RNA targeting subolesin and enolase were attached and fed normally on the rabbit's ear. Real-time polymerase chain reaction was used to confirm the extent of knockdown. RESULTS: Ticks in the subolesin or enolase dsRNA groups showed knockdown rates of 80% and 60% respectively. Ticks in the combination dsRNA (subolesin and enolase) group showed an 80% knockdown. Knockdown of subolesin and enolase resulted in significant depletion in feeding, blood engorgement weight, attachment rate, and egg laying. Silencing of both resulted in a significant (p < 0.05) reduction in tick engorgement, egg laying, egg hatching (15%), and reproduction. CONCLUSIONS AND RELEVANCE: Our results suggest that subolesin and enolase are an exciting target for future tick control strategies.

First identification of Cytauxzoon manul in Eurasian lynx (Lynx lynx) in northwestern China.

BACKGROUND: Multiple species of the genera Cytauxzoon and Hepatozoon can infect wild felines, but the diversity of these and other apicomplexan parasites in Eurasian lynx is scarcely known. The aim of this study was to detect Cytauxzoon and Hepatozoon species with molecular methods in Eurasian lynxes and their ticks in northwestern China. METHODS: DNA was extracted from the heart, liver, spleen, lung, and kidney samples of three Eurasian lynxes as well as from their five ixodid ticks. These DNA samples were screened with polymerase chain reactions (PCRs) for Cytauxzoon with the partial cytochrome b gene (CytB), cytochrome c oxidase subunit I gene (COI), and small subunit ribosomal RNA gene (18S rRNA), and Hepatozoon with three different fragments of small subunit ribosomal RNA gene (18S rRNA). PCR products were sequenced, aligned, and phylogenetically analyzed. RESULTS: One adult female of Eurasian lynx (#1, adult female) was co-infected with Cytauxzoon manul and Hepatozoon felis genotype I, while an adult male lynx (#2) was infected with C. manul. Interestingly, H. felis genotype I was both detected in a male cub (#3) and two out of five infesting Hyalomma asiaticum ticks. CONCLUSIONS: For the first time, Cytauxzoon manul is reported here from Eurasian lynx. In addition, H. felis has not been known to occur in this host species in China and Central Asia. Thus, the findings of this study extend our knowledge on the geographical distribution and host range of these haemoprotozoan parasites. Moreover, this is also the first evidence of C. manul and H. felis co-infection in Eurasian lynx.

Comparative analysis of essential oil efficacy against the Asian longhorned tick Haemaphysalis longicornis (Acari: Ixodidae).

This study evaluated the potential repellent and acaricidal effects of 4 essential oils (clove, eucalyptus, lavender, and mint) against the Asian longhorned tick Haemaphysalis longicornis, a vector of various tick-borne diseases in medical and veterinary contexts. Selected for their potential repellent and acaricidal properties, the 4 essential oils were tested on adult and nymph H. longicornis ticks at different concentrations. The experiment assessed mortality rates and repellency, particularly during tick attachment to host skin. There was a significant increase (p<0.05) in tick mortality and repellency scores across all groups. At a 1% concentration, adult tick mortality ranged from 36% to 86%, while nymph mortality ranged from 6% to 97%. Clove oil exhibited notable efficacy, demonstrating high mortality rates of nymphs and adults. Clove oil also displayed strong repellency properties, with a repellency index of 0.05, surpassing those of mint, eucalyptus, and lavender oils. Clove oil showed the highest effectiveness in deterring nonattached adult ticks (90%) and nymphs (95%) when applied to skin. Clove oil was the most effective against adult and nymph ticks, achieving mortality rates of 86% and 97%, respectively, and led to the highest nonattachment rates when applied to skin. In conclusion, essential oils such as clove, eucalyptus, lavender, and mint oils present promising results for tick population control.

Molecular cloning, identification, transcriptional analysis, and silencing of enolase on the life cycle of Haemaphysalis longicornis (Acari, Ixodidae) tick.

Ticks, blood-sucking ectoparasites, spread diseases to humans and animals. Haemaphysalis longicornis is a significant vector for tick-borne diseases in medical and veterinary contexts. Identifying protective antigens in H. longicornis for an anti-tick vaccine is a key tick control strategy. Enolase, a multifunctional protein, significantly converts D-2-phosphoglycerate and phosphoenolpyruvate in glycolysis and gluconeogenesis in cell cytoplasm. This study cloned a complete open reading frame (ORF) of enolase from the H. longicornis tick and characterized its transcriptional and silencing effect. We amplified the full-length cDNA of the enolase gene using rapid amplification of cDNA ends. The complete cDNA, with an ORF of 1,297 nucleotides, encoded a 432-amino acid polypeptide. Enolase of the Jeju strain H. longicornis exhibited the highest sequence similarity with H. flava (98%), followed by Dermacentor silvarum (82%). The enolase motifs identified included N-terminal and C-terminal regions, magnesium binding sites, and several phosphorylation sites. Reverse transcription-polymerase chain reaction (RT-PCR) analysis indicated that enolase mRNA transcripts were expressed across all developmental stages of ticks and organs such as salivary gland and midgut. RT-PCR showed higher transcript levels in syn-ganglia, suggesting that synganglion nerves influence enolase,s role in tick salivary glands. We injected enolase double-stranded RNA into adult unfed female ticks, after which they were subsequently fed with normal unfed males until they spontaneously dropped off. RNA interference significantly (P<0.05) reduced feeding and reproduction, along with abnormalities in eggs (no embryos) and hatching. These findings suggest enolase is a promising target for future tick control strategies.

Receptor for Advanced Glycation End Product (RAGE) Modulates Inflammation During Feeding of the Hard Tick, Haemaphysalis longicornis in Mice.

Ticks are notorious blood-sucking ectoparasites that affect both humans and animals. They serve as a unique vector of various deadly diseases. Here, we have shown the roles of the receptor for advanced glycation end products (RAGE) during repeated infestations by the tick Haemaphysalis longicornis using RAGE-/- mice. In primary infestation, a large blood pool developed, which was flooded with numerous RBCs, especially during the rapid feeding phase of the tick both in wild-type (wt) and RAGE-/- mice. Very few inflammatory cells were detected around the zones of haemorrhage in the primary infestations. However, the number of inflammatory cells gradually increased in the subsequent tick infestations, and during the third infestations, the number of inflammatory cells reached to the highest level (350.3 ± 16.8 cells/focus). The site of attachment was totally occupied by the inflammatory cells in wt mice, whereas very few cells were detected at the ticks' biting sites in RAGE-/- mice. RAGE was highly expressed during the third infestation in wt mice. In the third infestation, infiltration of CD44+ lymphocytes, eosinophils and expression of S100A8 and S100B significantly increased at the biting sites of ticks in wt, but not in RAGE-/- mice. In addition, peripheral eosinophil counts significantly increased in wt but not in RAGE-/- mice. Taken together, our study revealed that RAGE-mediated inflammation and eosinophils played crucial roles in the tick-induced inflammatory reactions.

Molecular characterization and induced changes of histone acetyltransferases in the tick Haemaphysalis longicornis in response to cold stress.

BACKGROUND: Epigenetic modifications of histones play important roles in the response of eukaryotic organisms to environmental stress. However, many histone acetyltransferases (HATs), which are responsible for histone acetylation, and their roles in mediating the tick response to cold stress have yet to be identified. In the present study, HATs were molecularly characterized and their associations with the cold response of the tick Haemaphysalis longicornis explored. METHODS: HATs were characterized by using polymerase chain reaction (PCR) based on published genome sequences, followed by multiple bioinformatic analyses. The differential expression of genes in H. longicornis under different cold treatment conditions was evaluated using reverse transcription quantitative PCR (RT-qPCR). RNA interference was used to explore the association of HATs with the cold response of H. longicornis. RESULTS: Two HAT genes were identified in H. longicornis (Hl), a GCN5-related N-acetyltransferase (henceforth HlGNAT) and a type B histone acetyltransferase (henceforth HlHAT-B), which are respectively 960 base pairs (bp) and 1239 bp in length. Bioinformatics analysis revealed that HlGNAT and HlHAT-B are unstable hydrophilic proteins characterized by the presence of the acetyltransferase 16 domain and Hat1_N domain, respectively. RT-qPCR revealed that the expression of HlGNAT and HlHAT-B decreased after 3 days of cold treatment, but gradually increased with a longer period of cold treatment. The mortality rate following knockdown of HlGNAT or HlHAT-B by RNA interference, which was confirmed by RT-qPCR, significantly increased (P < 0.05) when H. longicornis was treated at the lowest lethal temperature (- 14 °C) for 2 h. CONCLUSIONS: The findings demonstrate that HATs may play a crucial role in the cold response of H. longicornis. Thus further research is warranted to explore the mechanisms underlying the epigenetic regulation of the cold response in ticks.

Biological response to Przewalski's horse reintroduction in native desert grasslands: a case study on the spatial analysis of ticks.

BACKGROUND: Reintroduction represents an effective strategy for the conservation of endangered wildlife, yet it might inadvertently impact the native ecosystems. This investigation assesses the impact of reintroducing endangered Przewalski's horses into the desert grassland ecosystem of the Kalamaili Nature Reserve (KNR), particularly its effect on the spatial distribution of ticks. In a 25 km2 core area of Przewalski's horse distribution, we set up 441 tick sampling sites across diverse habitats, including water sources, donkey trails, and grasslands, recording horse feces and characteristics to analyze the occurrence rate of ticks. Additionally, we gathered the data of 669 fresh feces of horses. To evaluate the spatial dynamics between these feces and ticks, we used methods such as Fixed Kernel Estimation (FKE), Moran's I spatial autocorrelation index, and Generalized Linear Models (GLM). RESULTS: The dominant species of ticks collected in the core area were adult Hyalomma asiaticum (91.36%). Their occurrence rate was higher near donkey trails (65.99%) and water sources (55.81%), particularly in areas with the fresh feces of Przewalski's horses. The ticks' three risk areas, as defined by FKE, showed significant overlap and positive correlation with the distribution of Przewalski's horses, with respective overlap rates being 90.25% in high risk, 33.79% in medium risk, and 23.09% in low risk areas. Moran's I analysis revealed a clustering trend of the fresh feces of Przewalski's horses in these areas. The GLM confirmed a positive correlation between the distribution of H. asiaticum and the presence of horse fresh feces, alongside a negative correlation with the proximity to water sources and donkey trails. CONCLUSIONS: This study reveals the strong spatial correlation between Przewalski's horses and H. asiaticum in desert grasslands, underlining the need to consider interspecific interactions in wildlife reintroductions. The findings are crucial for shaping effective strategies of wildlife conservation and maintaining ecological balance.

Phenology of five tick species in the central Great Plains.

The states of Kansas and Oklahoma, in the central Great Plains, lie at the western periphery of the geographic distributions of several tick species. As the focus of most research on ticks and tick-borne diseases has been on Lyme disease which commonly occurs in areas to the north and east, the ticks of this region have seen little research attention. Here, we report on the phenology and activity patterns shown by tick species observed at 10 sites across the two states and explore factors associated with abundance of all and life specific individuals of the dominant species. Ticks were collected in 2020-2022 using dragging, flagging and carbon-dioxide trapping techniques, designed to detect questing ticks. The dominant species was A. americanum (24098, 97%) followed by Dermacentor variabilis (370, 2%), D. albipictus (271, 1%), Ixodes scapularis (91, <1%) and A. maculatum (38, <1%). Amblyomma americanum, A. maculatum and D. variabilis were active in Spring and Summer, while D. albipictus and I. scapularis were active in Fall and Winter. Factors associated with numbers of individuals of A. americanum included day of year, habitat, and latitude. Similar associations were observed when abundance was examined by life-stage. Overall, the picture is one of broadly distributed tick species that shows seasonal limitations in the timing of their questing activity.

Ecoclimate drivers shape virome diversity in a globally invasive tick species.

Spillovers of viruses from animals to humans occur more frequently under warmer conditions, particularly arboviruses. The invasive tick species Haemaphysalis longicornis, the Asian longhorned tick, poses a significant public health threat due to its global expansion and its potential to carry a wide range of pathogens. We analyzed meta-transcriptomic data from 3595 adult H. longicornis ticks collected between 2016 and 2019 in 22 provinces across China encompassing diverse ecological conditions. Generalized additive modeling revealed that climate factors exerted a stronger influence on the virome of H. longicornis than other ecological factors, such as ecotypes, distance to coastline, animal host, tick gender, and antiviral immunity. To understand how climate changes drive the tick virome, we performed a mechanistic investigation using causality inference with emphasis on the significance of this process for public health. Our findings demonstrated that higher temperatures and lower relative humidity/precipitation contribute to variations in animal host diversity, leading to increased diversity of the tick virome, particularly the evenness of vertebrate-associated viruses. These findings may explain the evolution of tick-borne viruses into generalists across multiple hosts, thereby increasing the probability of spillover events involving tick-borne pathogens. Deep learning projections have indicated that the diversity of the H. longicornis virome is expected to increase in 81.9% of regions under the SSP8.5 scenario from 2019 to 2030. Extension of surveillance should be implemented to avert the spread of tick-borne diseases.

Discovery of Colpodella spp. in ticks (Hyalomma dromedarii) infesting camels in southern Egypt.

In Egypt, tick-borne diseases pose a significant threat to human and animal health, and the threat to dromedaries (Camelus dromedarius), the country's dominant camelid species, is of particular concern. These animals are frequently infested with ticks, and may thus develop tick-borne diseases or become reservoirs of tick-borne pathogens. However, there is a paucity of data on tick infestation in Egyptian camels, especially in the south of the country. Accordingly, we aimed to determine the prevalence of tick infestation in southern Egyptian camel populations (in Luxor and Aswan governorates), and identify the hemoprotozoan parasites carried by camel-infesting ticks. Camels were checked for ticks during veterinary examination at quarantine and household checks, and ticks were collected from infested camels for species identification using morphological examination and PCR analyses. Tick and hemoprotozoan species were identified using Basic Local Alignment Search Tool analysis with subsequent confirmation in phylogenetic analyses. All camel-infesting ticks belonged to the species Hyalomma dromedarii, and were clustered with ticks of this species previously found in Egypt in a phylogenetic tree based on the 16S rRNA gene. Molecular analysis targeting the 18S rRNA gene revealed the presence of hitherto undetected hemoprotozoan parasites, Colpodella spp., in 30/297 (10.1 %) camel-infesting ticks. In phylogenetic analysis, these Colpodella spp. were highly homologous (94-98.6 %) with Colpodella spp. previously deposited in GenBank with accession numbers OQ540590Q, MH208621, and GQ411073, which relate to Colpodella spp. previously detected from Haemaphysalis longicornis, Rhipicephalus haemaphysaloides, and humans in China. PCR analyses with spherical body protein-4 (SBP-4) gene-specific primers revealed Babesia bovis in 16/297 (5 %) of camel-infesting ticks, however, Babesia bigemina and Theileria annulata were not detected. Here, we report the first detection of Colpodella spp. in H. dromedarii in Egypt. Further epidemiological studies are needed to assess the risk to camels and humans, and the transmission dynamics. Based on the high tick infestation rates in Egyptian camels and the identification of previously unreported protozoan hemoparasites in ticks, we consider that the dromedary should be subject to surveillance as a sentinel species for tick-borne diseases in Egypt. Our findings underline the need for surveillance and collecting data on lesser known pathogens circulating in camel-infesting ticks, as part of a public health strategy for dealing with tick-borne diseases in Egypt.

First molecular survey of tick-borne protozoan and bacterial pathogens in the questing tick population in Bangladesh.

Questing ticks carry various tick-borne pathogens (TBPs) that are responsible for causing tick-borne diseases (TBDs) in humans and animals around the globe, especially in the tropics and sub-tropics. Information on the distribution of ticks and TBPs in a specific geography is crucial for the formulation of mitigation measures against TBDs. Therefore, this study aimed to survey the TBPs in the questing tick population in Bangladesh. A total of 2748 questing hard ticks were collected from the pastures in Sylhet, Bandarban, Sirajganj, Dhaka, and Mymensingh districts through the flagging method. After morphological identification, the ticks were grouped into 142 pools based on their species, sexes, life stages, and collection sites. The genomic DNA extracted from tick specimens was screened for 14 pathogens, namely Babesia bigemina (AMA-1), Babesia bovis (RAP-1), Babesia naoakii (AMA-1), Babesia ovis (18S rRNA), Theileria luwenshuni (18S rRNA), Theileria annulata (Tams-1), Theileria orientalis (MPSP), Anaplasma marginale (groEL), Anaplasma phagocytophilum (16S rRNA), Anaplasma bovis (16S rRNA), Anaplasma platys (16S rRNA), Ehrlichia spp. (16S rRNA), Rickettsia spp. (gltA), and Borrelia (Bo.) spp. (flagellin B) using genus and species-specific polymerase chain reaction (PCR) assays. The prevalence of the detected pathogens was calculated using the maximum likelihood method (MLE) with 95 % confidence interval (CI). Among 2748 ixodid ticks, 2332 (84.86 %) and 416 (15.14 %) were identified as Haemaphysalis bispinosa and Rhipicephalus microplus, respectively. Haemaphysalis bispinosa was found to carry all the seven detected pathogens, while larvae of R. microplus were found to carry only Bo. theileri. Among the TBPs, the highest detection rate was observed in A. bovis (20/142 pools, 0.81 %, CI: 0.51-1.20), followed by T. orientalis (19/142 pools, 0.72 %, CI: 0.44-1.09), T. luwenshuni (9/142 pools, 0.34 %, CI: 0.16-0.62), B. ovis (4/142 pools, 0.15 %, CI: 0.05 - 0.34) and Bo. theileri (4/142 pools, 0.15 %, CI: 0.05-0.34), Ehrlichia ewingii (3/142 pools, 0.11 %, CI: 0.03-0.29), and Babesia bigemina (1/142, 0.04 %, CI: 0.00 - 0.16). This study reports the existence of T. luwenshuni, E. ewingii, and Bo. theileri in Bangladesh for the first time. The novel findings of this study are the foremost documentation of transovarian transmission of B. bigemina and E. ewingii in H. bispinosa and also provide primary molecular evidence on the presence of E. ewingii and Bo. theileri in H. bispinosa. Therefore, this study may shed light on the circulating TBPs in ticks in the natural environment and thereby advocate awareness among physicians and veterinarians to control and prevent TBDs in Bangladesh.