Identification of ticks and tick-borne pathogens of wildlife necropsy cases submitted to the SANBI National Zoological Gardens, South Africa.

Ticks are arachnid blood-feeding parasites, which infest livestock, wildlife, and humans, transmitting medically and veterinary significant pathogens. Their biodiversity and distribution in wild animals remains complex. This study analysed archived tick samples (n = 48) from the South African Biodiversity Institute (SANBI) Wildlife Biobank utilizing morphology and genetic analyses of the 16S rRNA and COI (DNA barcoding) mitochondrial genes to identify ticks collected among 13 vertebratesavian, reptilian, and mammalian host species. The specimens came from nine localities including nature reserves and captive facilities (zoological garden) in South Africa, Namibia, and Botswana. These ticks were also assessed for associated pathogens with the reverse line blot (RLB) hybridization assay. Seven tick genera, Amblyomma, Hyalomma, Haemaphysalis, Ixodes, Rhipicephalus, Rhipicentor, and Otobius were identified, with Amblyomma being the most prevalent (22.9 %) in our sample set. Obtained sequences were 95-100 % similar to published records of tick species collected from wild and domestic animals, as well as those collected from vegetation, from different southern African areas. However, tick specimens (n = 3) identified morphologically as Hyalomma truncatum, Rhipicephalus e. evertsi, and R. simus, were, on a molecularly level, more closely related to their sister taxa (H. glabrum, R. e. mimeticus, and R. gertrudae, respectively) suggesting a need for taxonomic verification. With the RLB hybridization assay, six samples reacted with the Ehrlichia/Anaplasma genus-specific probe, while two reacted with the Theileria/Babesia genus-specific probe. Sequencing of the RLB amplicons targeting the 18S rRNA gene (n = 2) indicated 100 % similarity to Hepatozoon fitzsimonsi, while one was closely related to He. ingwe with 99.39 % similarity. The results show that wildlife harbour different tick species, and pathogen detection identified novel genotypes, indicating wildlife as potential pathogens reservoirs. This study enhances our understanding of tick biodiversity, distribution and highlights wildlife's role in harbouring diverse tick species and novel pathogens.

Molecular detection of Rickettsia aeschlimannii, Candidatus Rickettsia shennongii, Rickettsia sp. and Coxiella burnetii in ticks collected from camels.

Tick-borne bacteria of the genera Rickettsia and Coxiella cause several emerging veterinary and human infectious diseases. Ticks of the genus Hyalomma are medically important vectors due to their potential role in the transmission of pathogens to vertebrate hosts. There is an inadequate knowledge on tick-borne Rickettsia spp. and Coxiella spp. in ticks infesting transhumant camels in Pakistan. In this study, we conducted a molecular survey for screening of Rickettsia spp. and Coxiella spp. in ticks infesting camels. Seven hard tick species including Hyalomma dromedarii, Hyalomma anatolicum, Hyalomma scupense, Hyalomma isaaci, Hyalomma turanicum, Hyalomma asiaticum, and Rhipicephalus sanguineus s.l were confirmed on camels in three distinct physiographic regions of Khyber Pakhtunkhwa, Pakistan. A subset of morphologically identified ticks were subjected to molecular assays for the genetic characterization of ticks and the detection and genetic characterization of Rickettsia and Coxiella species using standard genetic markers. Ticks screened for pathogens resulted in the detection of Rickettsia aeschlimannii and Candidatus Rickettsia shennongii and Coxiella burnetii. The molecular analysis further reveals the presences of an undetermined Rickettsia aeschlimannii-like species, that is making a distinct phylogenetic clade with R. aeschlimannii. The detection of pathogens in camel ticks poses potential health hazards as these ticks frequently bites humans. Molecular screening of Rickettsia spp. and Coxiella spp. associated with camel ticks is a preliminary step toward the surveillance of evaluating their zoonotic threats in the region.

The epidemiological and infectious characteristics of novel types of Coxiella burnetii co-infected with Coxiella-like microorganisms from Xuyi County, Jiangsu province, China.

Coxiella burnetii (C. burnetii) is the causative agent of Q fever, a type of zoonoses withwidespread distribution. In 2019, a case of Q fever was diagnosed by metagenomic next-generation sequencing (mNGS) method in Xuyi County (Jiangsu province, China). The seroprevalence of previous fever patients and the molecular epidemiology of Coxiella in wild hedgehogs and harbouring ticks around the confirmed patient were detected to reveal the genetic characteristics and pathogenicity of the Coxiella strains. Four of the 90 serum samples (4.44%) were positive for specific C. burnetii IgM antibody, suggesting that local humans are at risk of Q fever. The positive rates of C. burnetii in hedgehogs and ticks were 21.9% (7/32) and 70.5% (122/173), respectively. At least 3 strains of Coxiella were found prevalent in the investigated area, including one new genotype of pathogenic C. burnetii (XYHT29) and two non-pathogenic Coxiella-like organisms (XYHT19 and XYHT3). XYHT29 carried by ticks and wild hedgehogs successfully infected mice, imposing a potential threat to local humans. XYHT19, a novel Coxiella-like microorganism, was first discovered in the world to co-infect with C. burnetii in Haemaphysalis flava. The study provided significant epidemic information that could be used for prevention and control strategies against Q fever for local public health departments and medical institutions.

Epidemiology and global spread of emerging tick-borne Alongshan virus.

The emergence and spread of novel viral pathogens is a major threat to human health, particularly in the context of climate and human-induced change in land use. Alongshan virus (ALSV) is a tick-borne virus associated with human disease, which was first identified in northeast China. More recently, several studies reported the emergence of ALSV in mammalian and arthropod hosts in multiple different countries outside of Asia, and the first viral genome sequencing data has become available. ALSV is a member of the Jingmenvirus group closely related to the Flaviviridae family. Unusually, the positive-sense, single-stranded RNA genome of ALSV is segmented and consists of four distinct segments, two of which show homology with the NS3 and NS5 protein encoding regions of non-segmented flaviviruses. Transmission of arthropod-borne pathogens will likely increase in the future due to environmental change mediated by a variety of environmental and ecological factors and increasing human encroachment into wild animal habitats. In this review, we present current knowledge of global ALSV distribution and emergence patterns, highlight genetic diversity, evolution and susceptible species. Finally, we discuss the role of this emerging tick-borne virus in the context of urbanization and global health.

Machine learning algorithms for the evaluation of risk by tick-borne pathogens in Europe.

BACKGROUND: Tick-borne pathogens pose a major threat to human health worldwide. Understanding the epidemiology of tick-borne diseases to reduce their impact on human health requires models covering large geographic areas and considering both the abiotic traits that affect tick presence, as well as the vertebrates used as hosts, vegetation, and land use. Herein, we integrated the public information available for Europe regarding the variables that may affect habitat suitability for ticks and hosts and tested five machine learning algorithms (MLA) for predicting the distribution of four prominent tick species across Europe. MATERIALS AND METHODS: A grid of cells 20 km in diameter was prepared to cover the entire territory, containing data on vegetation, points of water, habitat fragmentation, forest density, grass extension, or imperviousness, with information on temperature and water deficit. The distribution of the hosts (162 species) was modelled and included in the dataset. We used five MLA, namely, Random Forest, Neural Networks, Naive Bayes, Gradient Boosting, and AdaBoost, trained with reliable coordinates for Ixodes ricinus, Dermacentor reticulatus, Dermacentor marginatus, and Hyalomma marginatum in Europe. RESULTS: Both Random Forest and Gradient Boosting best predicted ticks and host environmental niches. Our results demonstrate that MLA can identify trait-matching combinations of environmental niches. The inclusion of land cover and land use variables has a superior capacity for predicting areas suitable for ticks, compared to classic methods based on the use of climate data alone. CONCLUSIONS: Flexible MLA-driven models may offer several advantages over traditional models. We anticipate that these results may be extrapolated to other regions and combinations of tick-vertebrates. These results highlight the potential of MLA for inference in ecology and provide a background for the evolution of a completely automatized tool to calculate the seasonality of ticks for early warning systems aimed at preventing tick-borne diseases.

A survey of the tick-borne disease Crimean-Congo hemorrhagic fever in southern Algeria: First serological evidence in the dromedary camel population.

Crimean-Congo hemorrhagic fever (CCHF) is a tick-borne viral zoonosis caused by a Nairovirus, Crimean-Congo hemorrhagic fever virus (CCHFV). Despite its wide geographical distribution, the epidemiology of CCHF in northern Africa is incompletely understood and its occurrence in Algeria is virtually unknown. The present survey aimed to determine the prevalence of CCHF antibodies and to identify the potential risk factors associated with CCHFV seropositivity among the one-humped camel (Camelus dromedarius) in southern Algeria. A total of 269 camels selected randomly from slaughterhouses in three wilayas were employed in the study. Sera sampled were tested for the presence of CCHFV-specific IgG antibodies using enzyme-linked immunosorbent assay (ELISA). CCHFV seropositivity was recorded in 255 out of 269 camels accounting for a prevalence rate of 94.8% (95%CI = 92.14-97.45). The seroprevalence by origin was determined to be 97% (193/199) in imported camels and 86% (49/57) in local ones (p > 0.25). Tick presence (OR = 12.35, 95%CI = 1.41-107.43, p < 0.05) was recorded as the only potential risk factor for contracting CCHFV. This study shows for the first time that camels are exposed to CCHFV in Algeria with a significantly high seroprevalence. It also underlines the need for further research to investigate the broader extent of circulating CCHFV in the country, whether in humans, animals, or ticks.

Differential interactions of Rickettsia species with tick microbiota in Rh. sanguineus and Rh. turanicus.

Tick-borne rickettsioses, caused by Gram-negative bacteria of the Rickettsia genus, pose a growing global threat, with various arthropod vectors contributing to their transmission. Understanding the complex interactions within tick microbiota, including the role of Rickettsia species, is crucial for elucidating the dynamics of rickettsial diseases. Here, we investigate the taxonomic profiles and co-occurrence networks of Rickettsia in Rh. sanguineus sensus lato (s.l.) and Rh. turanicus ticks, revealing significant differences in community composition and local connectivity of Rickettsia species. While the microbiota of both tick species share common taxa, distinct differences in relative abundance and network topology suggest unique ecological niches. Moreover, robustness analysis demonstrates varying resilience to perturbations, indicating different strategies for network organization. Our findings also highlight metabolic differences between tick species, suggesting potential implications for Rickettsia interactions. Overall, this study provides insights into the intricate microbial landscape within ticks, shedding light on the functional redundancy and metabolic pathways associated with Rickettsia, thus advancing our understanding of tick-borne diseases.

The prevalence of pathogens in ticks collected from humans in Belgium, 2021, versus 2017.

BACKGROUND: Ticks carry a variety of microorganisms, some of which are pathogenic to humans. The human risk of tick-borne diseases depends on, among others, the prevalence of pathogens in ticks biting humans. To follow-up on this prevalence over time, a Belgian study from 2017 was repeated in 2021. METHODS: During the tick season 2021, citizens were invited to have ticks removed from their skin, send them and fill in a short questionnaire on an existing citizen science platform for the notification of tick bites (TekenNet). Ticks were morphologically identified to species and life stage level and screened using multiplex qPCR targeting, among others, Borrelia burgdorferi (sensu lato), Anaplasma phagocytophilum, Borrelia miyamotoi, Neoehrlichia mikurensis, Babesia spp., Rickettsia helvetica and tick-borne encephalitis virus (TBEV). The same methodology as in 2017 was used. RESULTS: In 2021, the same tick species as in 2017 were identified in similar proportions; of 1094 ticks, 98.7% were Ixodes ricinus, 0.8% Ixodes hexagonus and 0.5% Dermacentor reticulatus. A total of 928 nymphs and adults could be screened for the presence of pathogens. Borrelia burgdorferi (s.l.) was detected in 9.9% (95% CI 8.2-12.0%), which is significantly lower than the prevalence of 13.9% (95% CI 12.2-15.7%) in 2017 (P = 0.004). The prevalences of A. phagocytophilum (4.7%; 95% CI 3.5-6.3%) and R. helvetica (13.3%; 95% CI 11.2-15.6%) in 2021 were significantly higher compared to 2017 (1.8%; 95% CI 1.3-2.7% and 6.8%; 95% CI 5.6-8.2% respectively) (P < 0.001 for both). For the other pathogens tested, no statistical differences compared to 2017 were found, with prevalences ranging between 1.5 and 2.9% in 2021. Rickettsia raoultii was again found in D. reticulatus ticks (n = 3/5 in 2021). Similar to 2017, no TBEV was detected in the ticks. Co-infections were found in 5.1% of ticks. When combining co-infection occurrence in 2017 and 2021, a positive correlation was observed between B. burgdorferi (s.l.) and N. mikurensis and B. burgdorferi (s.l.) and B. miyamotoi (P < 0.001 for both). CONCLUSIONS: Although the 2021 prevalences fell within expectations, differences were found compared to 2017. Further research to understand the explanations behind these differences is needed.

First molecular sequencing of Babesia gibsoni in ticks, Iraq.

Background: Tick is one of the most important ectoparasites distributed worldwide and plays an obvious role in the transmission of different infections to humans and animals as dogs. Aim: This study conducted to molecular demonstration of Babesia gibsoni in ticks of stray dogs and phylogenetic analysis of study isolates to detect their identity to global isolates. Prevalence of ticks in dogs, identification of tick species, and their relationship to some risk factors were aimed, also. Methods: A total of 97 stray dogs were inspected grossly to detect and collect ticks that existed in different body parts. After collection, all ticks were examined morphologically to identify their species, and then molecularly by the polymerase chain reaction (PCR) assay to detect B. gibsoni in different species of ticks. Local B. gibsoni isolates were sequenced, documented in the National Center For biotechnology information (NCBI) database, analyzed phylogenetically, and compared with the global GenBank-NCBI isolates. Results: In the current study, ticks were detected in 43.3% of dogs, and were shown to be varied in number and distribution among different body parts of each dog. Concerning its distribution, ticks were observed significantly on the abdomen, ear, and perineal region. In relation to risk factors, ticks were increased significantly in dogs <6 months old in comparison to older dogs, males more than females; and in rural areas more than dogs of sub-urban and urban areas. Based on morphology, different tick species were seen including Hylaomma anatolicum (86.12%), R. sanguineus (11.99%), and Rhipicephalus turanicus (1.89%). Targeting the 18S rRNA gene, PCR assay reported 3.79% positive ticks to B. gibsoni that were seen in R. sanguineus (13.16%) and H. anatolicum (2.56%). Based on phylogenetic analysis data of five local B. gibsoni isolates, this study demonstrated their close relations to the global NCBI-BLAST B. gibsoni Iraqi isolate (ID: MN385424.1). Conclusion: This represents the first Iraqi study that demonstrated molecularly B. gibsoni in different species of ticks that infected stray dogs.

Hitchhiker's Guide to Borrelia burgdorferi.

Don't Panic. In the nearly 50 years since the discovery of Lyme disease, Borrelia burgdorferi has emerged as an unlikely workhorse of microbiology. Interest in studying host-pathogen interactions fueled significant progress in making the fastidious microbe approachable in laboratory settings, including the development of culture methods, animal models, and genetic tools. By developing these systems, insight has been gained into how the microbe is able to survive its enzootic cycle and cause human disease. Here, we discuss the discovery of B. burgdorferi and its development as a model organism before diving into the critical lessons we have learned about B. burgdorferi biology at pivotal stages of its lifecycle: gene expression changes during the tick blood meal, colonization of a new vertebrate host, and developing a long-lasting infection in that vertebrate until a new tick feeds. Our goal is to highlight the advancements that have facilitated B. burgdorferi research and identify gaps in our current understanding of the microbe.

Tick-Derived Peptide Blocks Potassium Channel TREK-1.

Ticks transmit a variety of pathogens, including rickettsia and viruses, when they feed on blood, afflicting humans and other animals. Bioactive components acting on inflammation, coagulation, and the immune system were reported to facilitate ticks' ability to suck blood and transmit tick-borne diseases. In this study, a novel peptide, IstTx, from an Ixodes scapularis cDNA library was analyzed. The peptide IstTx, obtained by recombinant expression and purification, selectively inhibited a potassium channel, TREK-1, in a dose-dependent manner, with an IC50 of 23.46 ± 0.22 µM. The peptide IstTx exhibited different characteristics from fluoxetine, and the possible interaction of the peptide IstTx binding to the channel was explored by molecular docking. Notably, extracellular acidification raised its inhibitory efficacy on the TREK-1 channel. Our results found that the tick-derived peptide IstTx blocked the TREK-1 channel and provided a novel tool acting on the potassium channel.

Phenotypic and genotypic characterization of ticks and tick-borne pathogens from cattle in selected villages of Greater Letaba Municipality in Limpopo Province, South Africa.

Ticks are blood ectoparasites that feed on domestic, wild animals and humans. They spread a variety of infections such as protozoa, viruses, and bacteria. Moreover, cattle reared by smallholder farmers are susceptible to ticks and tick-borne pathogens. Therefore, accurate identification of ticks and detection of tick-borne pathogens is crucial. The main aim of this study was to identify and characterize ticks and tick-borne pathogens from selected villages in Greater Letaba Municipality, Limpopo Province, using morphological and molecular techniques. A total of 233 ticks were collected from cattle and identified morphologically using appropriate morphological keys. The following tick species were identified: Amblyomma hebraeum, Hyalomma rufipes, Hyalomma truncatum, Rhipicephalus appendiculatus, Rhipicephalus (Boophilus) decoloratus, Rhipicephalus (Boophilus) microplus, Rhipicephalus evertsi evertsi, and Rhipicephalus sanguineus. Rhipicephalus spp. was the most common species accounting to 73.8% of the identified ticks. The genomic DNA was extracted from the whole tick for tick identification and from midguts of the ticks for the detection of tick-borne pathogens, followed by amplification and sequencing. A total of 27 samples were positive for tick-borne pathogens: 23 samples tested positive for Theileria and four samples tested positive for Ehrlichia. Anaplasma and Rickettsial OmpB could not be detected from any of the samples. There was no obvious grouping of ticks and tick-borne pathogens on the bases of their locality. The findings of this study confirm previous reports that indicated that cattle reared by smallholder farmers harbor various ticks and tick-borne pathogens of veterinary, public health, and economic importance. Regular monitoring of tick infestations in villages around the study areas is recommended to avoid disease outbreaks.

Tick-borne Apicomplexa in wildlife and ticks of French Guiana.

Tick-borne Apicomplexa encompass a group of parasites responsible for significant medical and veterinary diseases, including babesiosis, theileriosis, and hepatozoonosis. In this study, we investigated the presence and diversity of tick-borne Apicomplexa in wildlife and ticks inhabiting the Amazon rainforests of French Guiana. To this end, we conducted molecular screening and typing using 18S rRNA sequences on a collection of 1161 specimens belonging to 71 species, including 44 species of wild mammals, five species of passerines, and 22 species of ticks. We characterized eight genovariants of Babesia, Theileria, Hemolivia, and Hepatozoon parasites, some matching known species, while others suggested potential novel species. These parasites were detected in wild mammals, including opossums, sloths, armadillos, porcupines, margays, greater grisons, and ticks, but not in passerines. Finally, similarities with surveys conducted in Brazil highlight the specific sylvatic transmission cycles of South American tick-borne Apicomplexa.

Title: Apicomplexes transmis par les tiques chez la faune sauvage et les tiques de Guyane française. Abstract: Les Apicomplexes transmis par les tiques englobent un groupe de parasites responsables de maladies médicales et vétérinaires importantes, notamment la babésiose, la theilériose et l'hépatozoonose. Dans cette étude, nous avons étudié la présence et la diversité des Apicomplexes transmis par les tiques dans la faune sauvage et les tiques habitant les forêts tropicales amazoniennes de Guyane française. À cette fin, nous avons effectué un criblage moléculaire et un typage à l'aide de séquences d'ARNr 18S sur une collection de 1 161 spécimens appartenant à 71 espèces, dont 44 espèces de mammifères sauvages, cinq espèces de passereaux et 22 espèces de tiques. Nous avons caractérisé huit génovariants des parasites Babesia, Theileria, Hemolivia et Hepatozoon, certains correspondant à des espèces connues tandis que d'autres suggéraient de nouvelles espèces potentielles. Ces parasites ont été détectés chez des mammifères sauvages, dont des opossums, des paresseux, des tatous, des porcs-épics, des margays, des grisons et des tiques, mais pas chez des passereaux. Enfin, des similitudes avec des enquêtes menées au Brésil mettent en évidence les cycles de transmission sylvatiques spécifiques des Apicomplexa transmis par les tiques d'Amérique du Sud.

16S rRNA metabarcoding for the identification of tick-borne bacteria in ticks in the Republic of Korea.

Ticks are blood-sucking ectoparasites that act as vectors for transmission of various pathogens. The purpose of this study was to assess tick-borne bacteria, whether pathogenic or not, in ticks distributed in Korea using 16S rRNA metabarcoding and to confirm the results by PCR. Questing ticks were collected from four provinces in Korea in 2021 using the flagging method. After pooling the DNAs from the 61 tick pools (including 372 ticks), the bacterial 16S rRNA V3-V4 hypervariable region was amplified and sequenced using the MiSeq platform. Rickettsia, Ehrlichia, and the endosymbiont Wolbachia were confirmed by conventional PCR and molecular analysis. In total, 6907 ticks (534 pools) were collected and identified as belonging to five species (Haemaphysalis spp., H. longicornis, H. flava, I. nipponensis, and A. testudinarium). Through 16S rRNA metabarcoding, 240 amplicon sequence variants were identified. The dominant taxa were Rickettsiella and Coxiella. Additionally, pathogenic bacteria such as Rickettsia and Ehrlichia, endosymbiotic bacteria such as Wolbachia and Spiroplasma were identified. Polymerase chain reaction (PCR) was performed to confirm the presence of Rickettsia, Ehrlichia, Bartonella, and Wolbachia in individual ticks. Overall, 352 (65.92%) of 534 pools tested positive for at least one of the screened tick-borne bacteria. Rickettsia was the most prevalent (61.42%), followed by Wolbachia (5.05%). Ehrlichia was detected in 4.86% of tested samples, whereas Bartonella was not detected. In this study, 16S rRNA metabarcoding revealed the presence of Rickettsia, Wolbachia, and Ehrlichia, in that order of abundance, while showing absence of Bartonella. These results were confirmed to exhibit the same trend as that of the conventional PCR. Therefore, large-scale screening studies based on pooling, as applied in this study, will be useful for examining novel or rare pathogens present in various hosts and vectors.

Ecological Changes Exacerbating the Spread of Invasive Ticks has Driven the Dispersal of Severe Fever with Thrombocytopenia Syndrome Virus Throughout Southeast Asia.

Severe fever with thrombocytopenia syndrome virus (SFTSV) is a tick-borne virus recognized by the World Health Organization as an emerging infectious disease of growing concern. Utilizing phylodynamic and phylogeographic methods, we have reconstructed the origin and transmission patterns of SFTSV lineages and the roles demographic, ecological, and climatic factors have played in shaping its emergence and spread throughout Asia. Environmental changes and fluctuations in tick populations, exacerbated by the widespread use of pesticides, have contributed significantly to its geographic expansion. The increased adaptability of Lineage L2 strains to the Haemaphysalis longicornis vector has facilitated the dispersal of SFTSV through Southeast Asia. Increased surveillance and proactive measures are needed to prevent further spread to Australia, Indonesia, and North America.

Tick chemosensation and implications for novel control strategies.

Ticks pose a major threat to the health of humans and animals. The use of synthetic acaricides and repellents has raised the concerns of potential health and environmental risks and increasing resistance in ticks. This article highlights the importance of the research on tick chemosensation in developing novel control agents. It provides a review on our current understanding of tick chemosensory system and proposes using chemosensory receptor (CR) genes as molecular targets to discover novel tick control agents. The releases of high-quality tick genomes provide unprecedented opportunities to explore CR gene repertoires. Further functional characterization is necessary to identify the receptors for key chemical cues and signals and unravel whether tick chemosensation involves ionotropic and/or metabotropic mechanisms.

Special Issue "Arbovirus Diagnostics".

Arboviruses are pathogens transmitted mainly by mosquitoes, ticks, and sandflies [...].

The Specificity of Epizootic and Epidemiological Processes in Natural Foci of Hemorrhagic Fever with Renal Syndrome and Tick-Borne Encephalitis in Russia, as the Basis for the Prospects of Creating a Combined Vaccine for the Prevention of These Infections.

Hemorrhagic fever with renal syndrome (HFRS) and tick-borne encephalitis (TBE) are the most common viral diseases in Russia. HFRS is caused by six different types of hantaviruses: Hantaan, Amur, Seoul, Puumala, Kurkino, and Sochi, which are transmitted to humans through small mammals of the Muridae and Cricetidae families. TBE is caused by viruses belonging to five different phylogenetic subtypes. The similarities in the ecology of HFRS and TBE pathogens is presented here. Hantavirus-infected small mammals can transmit the virus to uninfected animals, and ticks can also transmit hantavirus to other ticks and mammals. Hantavirus transmission from ticks to humans is possible only hypothetically based on indirect data. Over the past 23 years, 164,582 cases of HFRS (4.9 per 105 people) and 71,579 cases of TBE (2.5 per 105 people) were registered in Russia. The mortality rate was 0.4% (668 cases) in HFRS and 1.6% deaths (1136 cases) in TBE. There were 4030 HFRS (2.5%) and 9414 TBE (13%) cases in children under 14 years old. HFRS and TBE cases were registered in 42 out of 85 Russian regions; in 18-only HFRS, in 13-only TBE, and 12 had no reported cases. The prospects of applying a combined vaccine for HFRS and TBE prevention are shown in this paper.

Mouse Models for the Study of Borrelia burgdorferi Infection.

Lyme disease, a tickborne illness caused by Borrelia burgdorferi, is an emerging, significant public health concern. B. burgdorferi infections are challenging to study because of their complex life cycle that requires adaptation to both ticks and mammalian hosts for long-term survival and transmission. Bacterial adaptation is accomplished through extensive gene expression alterations in response to environmental cues that remain to be more fully explored. Mouse models of infection serve as valuable tools for studying B. burgdorferi adaptation to the mammalian host and the spirochete's ability to cause persistent infections and thus to interact with and evade the immune system. This article details three mouse models that differ in their primary methods of infection: infestation with B. burgdorferi infected ticks, intradermal inoculation of culture-grown spirochetes, and infection via subcutaneous transplantation of infected tissue. Each method offers unique advantages and limitations. Tick infestation is the route of natural transmission but presents logistical challenges. Syringe inoculation is easy and provides precise control over the infectious dose, but infection is with culture-adapted bacteria. Transplantation of infected tissue introduces mammalian-host-adapted B. burgdorferi in precise anatomical locations, but misses the transfer of tick factors affecting immunity. Detailed protocols are provided for each of the three infection routes, and pros and cons of each method are outlined to help researchers identify the best approach for a research question to be addressed. A protocol is also provided for the treatment of mice with antibiotics that reliably eliminates detectable spirochetes from the animals. © 2024 Wiley Periodicals LLC. Basic Protocol 1: Syringe inoculation of mice with cultured B. burgdorferi and collection of necropsy tissues Basic Protocol 2: Infection of mice with B. burgdorferi via tick infestation Basic Protocol 3: Infection of mice with host-adapted B. burgdorferi via tissue transplant Support Protocol: Clearance of B. burgdorferi by antibiotic treatment.