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Ticks are increasingly important vectors of human and agricultural diseases. While many studies have focused on tick-borne bacteria, far less is known about tick-associated viruses and their roles in public health or tick physiology. To address this, we investigated patterns of bacterial and viral communities across two field populations of western black-legged ticks (Ixodes pacificus). Through metatranscriptomic analysis of 100 individual ticks, we quantified taxon prevalence, abundance, and co-occurrence with other members of the tick microbiome. In addition to commonly found tick-associated microbes, we assembled 11 novel RNA virus genomes from Rhabdoviridae, Chuviridae, Picornaviridae, Phenuiviridae, Reoviridae, Solemovidiae, Narnaviridae and two highly divergent RNA virus genomes lacking sequence similarity to any known viral families. We experimentally verified the presence of these in I. pacificus ticks across several life stages. We also unexpectedly identified numerous virus-like transcripts that are likely encoded by tick genomic DNA, and which are distinct from known endogenous viral element-mediated immunity pathways in invertebrates. Taken together, our work reveals that I. pacificus ticks carry a greater diversity of viruses than previously appreciated, in some cases resulting in evolutionarily acquired virus-like transcripts. Our findings highlight how pervasive and intimate tick-virus interactions are, with major implications for both the fundamental biology and vectorial capacity of I. pacificus ticks.ImportanceTicks are increasingly important vectors of disease, particularly in the United States where expanding tick ranges and intrusion into previously wild areas has resulted in increasing human exposure to ticks. Emerging human pathogens have been identified in ticks at an increasing rate, and yet little is known about the full community of microbes circulating in various tick species, a crucial first step to understanding how they interact with each and their tick host, as well as their ability to cause disease in humans. We investigated the bacterial and viral communities of the Western blacklegged tick in California and found 11 previously uncharacterized viruses circulating in this population.

[Display omitted] • European Acrocephalidae show greater prevalence and variety of blood parasites compared with Emberiza schoeniclus. • Migrating birds exhibit variations in blood parasite prevalence and biodiversity depending on their migration routes. • Long-distance migrants of the genus Locustella displayed no infection by either blood parasite, indicating resistance. • The age of migratory birds serves as a key factor in delineating parasite transmission areas effectively. • Transmission areas were either limited to Europe or Africa, or transmission occurred in both regions. During their journeys, migratory birds encounter a wider range of parasites than residents, transporting them over vast distances. While some parasites are widely distributed, transmission is not inevitable and depends on the presence of competent arthropod vectors as well as parasite compatibility with native bird species. Distinguishing between parasite distribution and transmission areas is crucial for monitoring and assessing risks to native bird species, as distribution areas, with the appropriate conditions, could become potential transmission areas. In this study, blood samples from 455 reed-living birds of the genera Acrocephalus , Locustella , and Emberiza, collected in the nature reserve "Die Reit" in Hamburg, Germany were screened, targeting haemosporidian parasites, trypanosomes, and filarioid nematodes. Determination of migratory bird age was employed to ascertain the transmission area of the detected parasites. Transmission areas were determined, based on information provided by resident and juvenile birds as well as findings in competent vectors. Long-distance migratory birds of the genus Acrocephalus showed a higher prevalence and diversity of blood parasites compared with partially migratory birds such as Emberiza schoeniclus. Notably, an age-dependent difference in parasite prevalence was observed in Acrocephalus spp., but not in E. schoeniclus. Nematodes were absent in all examined bird species. Proposed transmission areas were identified for nine haemosporidian lineages, showing three different types of transmission area, either with limited transmission in Europe or Africa, or active transmission in both regions. [ABSTRACT FROM AUTHOR]

The European Board and College of Obstetrics and Gynaecology (EBCOG) and the European Network of Trainees in Obstetrics and Gynaecology (ENTOG) express their concerns on the effect of climate change and environmental pollution. This paper reviews the impact on reproductive health and the contribution to climate change by the field of obstetrics and gynaecology. It concludes that its contributors and the effects of climate change cause definite adverse consequences to fertility and adverse obstetric outcomes. Mankind, and obstetrics and gynaecology personnel as well, must be aware and responsible of its contribution to climate change and consider the impact of their actions and interventions. [ABSTRACT FROM AUTHOR]

Arthropod-borne rickettsioses comprise a wide variety of subtypes that are endemic in Cambodia, but there remains very little data on the geographic distribution of the pathogens or their vectors. Surveys were conducted in Koh Kong and Preah Sihanouk Provinces between September 2017 and June 2018 to collect ectoparasites from peridomestic animals and the environment using dragging and flagging methods. Collected ectoparasites were sorted and identified morphologically, then pooled by species, host, and location for molecular detection using Rickettsia genus- and species-specific qPCR and/or multilocus sequence typing (MLST) assays. A total of 14,254 ectoparasites were collected including seven new locality records. Rickettsia species were detected in 35.5% (174/505) of the pools screened representing 3,149 randomly selected ectoparasites from the total collected. Rickettsia asembonensis was detected in 89.6% (147/164) of Rickettsia-positive flea pools and 3.6% (6/164) of the flea pools were positive for both R. asembonensis and Rickettsia felis. Candidatus Rickettsia senegalensis from Ctenocephalides orientis fleas and Rickettsia sp. close to Rickettsia japonica and Rickettsia heilongjiangensis from Haemaphysalis ticks were identified by MLST. This appears to be the first report of these new ectoparasite records and rickettsial species in southern Cambodia, suggesting a potential health risk to military and civilians in this region. Author summary: Rickettsiae are Gram-negative bacteria that cause acute undifferentiated febrile illness in humans. These pathogens are associated with arthropods and primarily transmitted by ectoparasites such as ticks, fleas, and mites. In Cambodia, rickettsial diseases have been documented in local patients, travelers and military personnel. However, the lack of entomological studies and awareness of these diseases hindered our comprehensive understanding of these pathogens and their arthropod vectors. Our manuscript provides a description of ectoparasite diversity and sheds light on their potential role in rickettsial disease transmission. Through molecular techniques, we uncover the prevalence and diversity of Rickettsia species in ectoparasites collected from various animal hosts in Koh Kong and Preah Sihanouk province. Rickettsia asembonensis, Rickettsia felis, and Candidatus Rickettsia senegalensis were all identified from Ctenocephalides orientis fleas, while Rickettsia species closely related to Rickettsia japonica, Rickettsia heilongjiangensis, and Rickettsia raoultii were found from Haemaphysalis ticks. Additionally, Rickettsia were also detected in Heterodoxus spiniger lice and Laelapidae mites, although we were unable to characterize the species. Insights into this pathogen-vector-host interface will better inform healthcare professionals, leading to more accurate diagnoses and increased awareness for better management of these diseases. [ABSTRACT FROM AUTHOR]

More than 75 arboviruses are indigenous to Australia, of which at least 13 are known to cause disease in humans. Alphaviruses are the most common arboviruses, notably including Ross River and Barmah Forest viruses, which contribute a significant public health and economic burden in Australia. Both can cause febrile illness with arthritic symptoms. Each circulates nationally across diverse climates and environments, and has multi-host, multi-vector dynamics. Several medically important flaviviruses also circulate in Australia. Infection with Murray Valley encephalitis or Kunjin viruses is less common but is associated with brain inflammation. Key research priorities for Australian arboviruses aim to understand clinical manifestations, develop timely diagnostics, and identify transmission cycles that permit the maintenance of arboviruses. While these can now be answered for a handful of notifiable alpha- and flaviviruses there are others for which non-human vertebrate hosts and competent arthropod invertebrate vectors are still to be identified and/or whose role in transmission is not well understood. One or more of these 'neglected' arboviruses may be the causative agent of a proportion of the many thousands of fever-related illnesses reported annually in Australia that at present remain undiagnosed. Here, what is known about enzootic cycling of viruses between arthropod vectors and mammalian and avian reservoir hosts is summarised. How and to what extent these interactions influence the epidemiology of arbovirus transmission and infection is discussed. [ABSTRACT FROM AUTHOR]

Simple Summary: The deadliest animal in the world is, by far, the mosquito, which spreads numerous viral and parasitic infectious diseases. To control mosquito populations and improve surveillance and personal protective measures, the establishment of rapid, simple, and economic strategies to characterize mosquito fauna and its specific life traits is essential for effective vector management. The present study synthesizes existing evidence on the application of an innovative approach—matrix-assisted laser desorption/ionization–time-of-flight mass spectrometry (MALDI-TOF MS) profiling/biotyping—for the identification of mosquitoes and the analysis of certain life traits, such as vector species, blood-feeding sources, pathogenic agents within the mosquito, and its susceptibility to insecticides. The reliability, low cost, and high-throughput capacity make the MALDI-TOF MS profiling a valuable tool for monitoring and controlling mosquito-borne diseases. These findings, based on this innovative approach, have important implications for public health stakeholders in improving mosquito identification, surveillance, and management of vector-borne diseases. Mosquito-borne diseases are responsible for hundreds of thousands of deaths per year. The identification and control of the vectors that transmit pathogens to humans are crucial for disease prevention and management. Currently, morphological classification and molecular analyses via DNA barcoding are the standard methods used for vector identification. However, these approaches have several limitations. In the last decade, matrix-assisted laser desorption/ionization–time-of-flight mass spectrometry (MALDI-TOF MS) profiling has emerged as an innovative technology in biological sciences and is now considered as a relevant tool for the identification of pathogens and arthropods. Beyond species identification, this tool is also valuable for determining various life traits of arthropod vectors. The purpose of the present systematic review was to highlight the contribution of MALDI-TOF MS to the surveillance and control of mosquito-borne diseases. Published articles from January 2003 to August 2024 were retrieved, focusing on different aspects of mosquito life traits that could be determinants in disease transmission and vector management. The screening of the scientific literature resulted in the selection of 54 published articles that assessed MALDI-TOF MS profiling to study various mosquito biological factors, such species identification, life expectancy, gender, trophic preferences, microbiota, and insecticide resistance. Although a large majority of the selected articles focused on species identification, the present review shows that MALDI-TOF MS profiling is promising for rapidly identifying various mosquito life traits, with high-throughput capacity, reliability, and low cost. The strengths and weaknesses of this proteomic tool for vector control and surveillance are discussed. [ABSTRACT FROM AUTHOR]

Background: Tigers are protected under schedule I of the Wildlife Protection Act, 1972. The current report highlights the detection of Hepatoozoon felis in a tiger cub. The infection is transmitted by ingestion of infected tick, infected prey and carrion. It is subclinical in adults; however, the cubs and immunocompromised adults may show clinical symptoms. Concurrent infection with bacterial or viral infections may be fatal to the infected animal. Methods: Hepatozoonosis was detected by blood smear examination using Giemsa staining. A PCR targeting the 18S ribosomal RNA was used to confirm the infection. The amplicon was purified and sequenced using a sanger sequencer. The 18S ribosomal RNA fragment sequence was compared to the available sequences in NCBI database using the nucleotide BLAST Tool. Neighbour joining phylogenetic trees using the bootstrap method were constructed using MEGA X software. Result: The presence of an intermediate gamont stage in neutrophils was seen under high resolution. The 660 bp amplicon was purified, sequenced and analysed for identity using the nucleotide BLAST tool of NCBI. The sequence was found to be 99.32%, similar to Hepatozoon felis. The phylogenetic analysis by neighbour joining phylogenetic tree using the bootstrap method indicated similarity with other reported sequences of H. felis isolated from Asian Lions. The sequence, however, was very dissimilar to the previously reported H. felis isolated from Royal Bengal Tiger. Considering the potential threat Hepatozoonosis can have in the wild, the prevalence must be estimated in prey base, sympatric cat species and arthropod vectors. [ABSTRACT FROM AUTHOR]

Simple Summary: Dermacentor reticulatus is an arthropod vector with great medical and veterinary importance. Its wide distribution and biological characteristics determine its important role in the circulation of pathogens in the parasite–host system. Its occurrence range is divided into western and eastern populations, which are separated from each other by the so-called Dermacentor-free zone localized in central Poland. This study aimed to estimate the potential epidemiological significance of D. reticulatus in the new endemic focus west of the Vistula River (Upper Silesia, central–southern Poland) and its co-occurrence with Ixodes ricinus. The molecular studies revealed the presence of Rickettsia spp. in 23.8% of the D. reticulatus specimens. In turn, 94.1% of the I. ricinus adults were infected with B. burgdorferi s.l., 11.7% with Babesia spp., and 5.8% with Rickettsia spp. Polymicrobial infections were noted in 17.6% of the I. ricinus. Our finding emphasizes the risk of infestation by both tick species and the risk of tick-borne infections in an area previously thought to be free of Dermacentor ticks. It is necessary to enhance medical and veterinary services for the more efficient diagnosis and prevention of tick-borne diseases in this region. Dermacentor reticulatus (Acari: Ixodidae) is an important arthropod vector in medical and veterinary contexts. Its geographic range is divided into western and eastern populations separated by a "Dermacentor-free zone" in central Poland. Recent faunistic studies showed a new endemic locality of the species in Upper Silesia to the west of the Vistula River (central–southern Poland) and its co-occurrence with I. ricinus. The prevalence of five tick-borne pathogens (TBPs), e.g., B. burgdorferi s.l., Bartonella spp., Rickettsia spp., and Babesia spp., in the ticks was assessed with polymerase chain reaction (PCR) methods. The molecular studies revealed the presence of Rickettsia spp. in 23.8% of the D. reticulatus specimens. In turn, 94.1% of the I. ricinus adults were infected with B. burgdorferi s.l., 11.7 % with Babesia spp., and 5.8% with Rickettsia spp. Coinfections with two TBPs were noted in 17.6% of the I. ricinus. These findings highlight not only the risk of infestation by both tick species in an area previously considered Dermacentor-free, but also the high prevalence of TBPs in the study area. Increased focus on medical and veterinary services appears necessary to diagnose and prevent tick-borne diseases in this region. [ABSTRACT FROM AUTHOR]

Background: Urban areas are unique ecosystems with stark differences in species abundance and composition compared with natural ecosystems. These differences can affect pathogen transmission dynamics, thereby altering zoonotic pathogen prevalence and diversity. In this study, we screened small mammals from natural and urban areas in the Netherlands for up to 19 zoonotic pathogens, including viruses, bacteria, and protozoan parasites. Materials and Methods: In total, 578 small mammals were captured, including wood mice (Apodemus sylvaticus), bank voles (Myodes glareolus), yellow-necked mice (Apodemus flavicollis), house mice (Mus musculus), common voles (Microtus arvalis), and greater white-toothed shrews (Crocidura russula). We detected a wide variety of zoonotic pathogens in small mammals from both urban and natural areas. For a subset of these pathogens, in wood mice and bank voles, we then tested whether pathogen prevalence and diversity were associated with habitat type (i.e., natural versus urban), degree of greenness, and various host characteristics. Results: The prevalence of tick-borne zoonotic pathogens (Borrelia spp. and Neoehrlichia mikurensis) was significantly higher in wood mice from natural areas. In contrast, the prevalence of Bartonella spp. was higher in wood mice from urban areas, but this difference was not statistically significant. Pathogen diversity was higher in bank voles from natural habitats and increased with body weight for both rodent species, although this relationship depended on sex for bank voles. In addition, we detected methicillin-resistant Staphylococcus aureus, extended-spectrum beta-lactamase/AmpC-producing Escherichia coli, and lymphocytic choriomeningitis virus for the first time in rodents in the Netherlands. Discussion: The differences between natural and urban areas are likely related to differences in the abundance and diversity of arthropod vectors and vertebrate community composition. With increasing environmental encroachment and changes in urban land use (e.g., urban greening), it is important to better understand transmission dynamics of zoonotic pathogens in urban environments to reduce potential disease risks for public health. [ABSTRACT FROM AUTHOR]

The article discusses the need for improved biosecurity measures in pathogen research and proposes a "bottom-up" approach to enhance safety and security. The authors share their experience implementing a successful program at the University of Texas Medical Branch (UTMB) that requires principal investigators (PIs) to conduct comprehensive risk assessments for proposed studies involving human pathogens. The program involves a formal notification of use (NOU) submission that is extensively reviewed by the Institutional Biosafety Committee (IBC). The authors suggest that this approach can be applied nationally with appropriate policy guidance and support, and emphasize the importance of training, access to biocontainment laboratories, and collaboration between institutions. [Extracted from the article]

Lumpy skin disease (LSD) is an economically important and notifiable transboundary viral disease of cattle and water buffalo, predominantly transmitted by arthropod vectors. In recent times, LSD has emerged as a notable concern in Nepal, with the first outbreak reported in June 2020, in Morang district. In 2022, outbreaks of LSD were observed in several districts with Nawalpur district being the hard‐hit district. The objective of this study is to provide insights into the epidemiological characteristics of LSD, to identify potential sources and associated risk factors for LSD outbreak in Nawalpur, and its financial impact. The overall morbidity rate was observed to be 28.02% (n = 431/1,538) and the mortality rate was 3.06% (n = 47/1,538), resulting in a case fatality rate of 10.90% (n = 47/431). The predominant clinical symptoms were skin nodules, lameness, and decreased milk production in milking animals. Dry cattle, including pregnant cows and cattle heifers were the most affected. Univariable logistic regression analysis identified factors linked to disease outbreaks, such as importing animals from disease prevalent regions, sharing feed and water, herd size, and the presence of clinical signs in neighboring farms. Multivariable analysis highlighted the significance of neighboring farms having sick animals in resulting disease outbreaks. Because of the substantial economic impact due to LSD, it is imperative to implement effective control and preventive measures. These include animal movement control and quarantine, following biosecurity protocols during nearby outbreaks, and targeted vaccination of susceptible populations to prevent further disease spread. [ABSTRACT FROM AUTHOR]

Rickettsia, a group of intracellular bacteria found in eukaryotes, exhibits diverse lifestyles, with some acting as vertebrate pathogens transmitted by arthropod vectors and others serving as maternally transmitted arthropod endosymbionts, some of which manipulate host reproduction for their own benefit. Two phenotypes, namely male-killing and parthenogenesis induction are known as Rickettsia-induced host reproductive manipulations, but it remains unknown whether Rickettsia can induce other types of host manipulation. In this study, we discovered that Rickettsia induced strong cytoplasmic incompatibility (CI), in which uninfected females produce no offspring when mated with infected males, in the predatory insect Nesidiocoris tenuis (Hemiptera: Miridae). Molecular phylogenetic analysis revealed that the Rickettsia strain was related to Rickettsia bellii, a common insect endosymbiont. Notably, this strain carried plasmid-encoded homologues of the CI-inducing factors (namely cifA-like and cifB-like genes), typically found in Wolbachia, which are well-known CI-inducing endosymbionts. Protein domain prediction revealed that the cifB-like gene encodes PD-(D/E)XK nuclease and deubiquitinase domains, which are responsible for Wolbachia-induced CI, as well as ovarian tumour-like (OTU-like) cysteine protease and ankyrin repeat domains. These findings suggest that Rickettsia and Wolbachia endosymbionts share underlying mechanisms of CI and that CI-inducing ability was acquired by microbes through horizontal plasmid transfer. [ABSTRACT FROM AUTHOR]

Mycoplasma agalactiae (Ma) is considered the primary causative agent of contagious agalactia (CA) in sheep and goats, which causes severe losses to the small ruminant dairy industry. As early as 1816, it was thought that environmental factors played a role in pathogen maintenance in endemic areas. Specifically, recent studies hypothesized a vector role for arthropods in the epidemiology of disease. The aim of this study was to investigate the presence and anatomical localization of Ma in naturally infected Riphicephalus bursa ticks to better evaluate tick–pathogen interactions. Salivary glands and ovaries of confirmed Ma-positive R. bursa were analyzed to look for the Ma antigen using immunohistochemistry (IHC). IHC showed strong positivity to Ma in the cytoplasm of salivary cells as well as in cells from the ovary. Our work demonstrated for the first time the crossing of the tick midgut barrier by Ma and the subsequent infection of organs capable of spreading the infection, and this result represents an absolute novelty in disease-related knowledge. Our preliminary results provide conclusive evidence of the potential vector role represented by hard ticks in the epidemiology of CA. Further field and laboratory investigations are necessary to confirm the tick role in the transmission of clinical CA. [ABSTRACT FROM AUTHOR]

The past three decades have seen an increasing number of emerging arthropod-borne viruses in temperate regions This process is ongoing, driven by human activities such as inter-continental travel, combined with the parallel emergence of invasive arthropods and an underlying change in climate that can increase the risk of virus transmission and persistence. In addition, natural events such as bird migration can introduce viruses to new regions. Despite the apparent regularity of virus emergence, arthropod-borne viruses circulating in temperate regions face the challenge of the late autumn and winter months where the arthropod vector is inactive. Viruses therefore need mechanisms to overwinter or they will fail to establish in temperate zones. Prolonged survival of arthropod-borne viruses within the environment, outside of both vertebrate host and arthropod vector, is not thought to occur and therefore is unlikely to contribute to overwintering in temperate zones. One potential mechanism is continued infection of a vertebrate host. However, infection is generally acute, with the host either dying or producing an effective immune response that rapidly clears the virus. There are few exceptions to this, although prolonged infection associated with orbiviruses such as bluetongue virus occurs in certain mammals, and viraemic vertebrate hosts therefore can, in certain circumstances, provide a route for long-term viral persistence in the absence of active vectors. Alternatively, a virus can persist in the arthropod vector as a mechanism for overwintering. However, this is entirely dependent on the ecology of the vector itself and can be influenced by changes in the climate during the winter months. This review considers the mechanisms for virus overwintering in several key arthropod vectors in temperate areas. We also consider how this will be influenced in a warming climate. [ABSTRACT FROM AUTHOR]

Hemotrophic mycoplasmas (HMs) are highly host-adapted and specialized pathogens infecting a wide range of mammals including farm animals, i.e., pigs, cattle, sheep, and goats. Although HMs have been known for over 90 years, we still do not know much about the natural transmission routes within herds. Recently, it has been repeatedly discussed in publications that arthropod vectors may play a role in the transmission of HMs from animal to animal. This is mainly since several HM species could be detected in different potential arthropod vectors by PCR. This review summarizes the available literature about the transmission of bovine, porcine, ovine, and caprine HM species by different hematophagous arthropod vectors. Since most studies are only based on the detection of HMs in potential vectors, there are rare data about the actual vector competence of arthropods. Furthermore, there is a need for additional studies to investigate, whether there are biological vectors in which HMs can multiply and be delivered to new hosts. [ABSTRACT FROM AUTHOR]

Background: Arthropods vector a multitude of human disease-causing organisms, and their geographic ranges are shifting rapidly in response to changing climatic conditions. This is, in turn, altering the landscape of disease risk for human populations that are brought into novel contact with the vectors and the diseases they carry. Sand flies in the genera Lutzomyia and Pintomyia are vectors of serious disease-causing agents such as Leishmania (the etiological agent of leishmaniasis) and may be expanding their range in the face of climate change. Understanding the climatic conditions that vector species both tolerate physiologically and prefer behaviorally is critical to predicting the direction and magnitude of range expansions and the resulting impacts on human health. Temperature and humidity are key factors that determine the geographic extent of many arthropods, including vector species. Methods: We characterized the habitat of two species of sand flies, Lutzomyia longipalpis and Pintomyia evansi. Additionally, we studied two behavioral factors of thermal fitness–thermal and humidity preference in two species of sand flies alongside a key aspect of physiological tolerance–desiccation resistance. Results: We found that Lu. longipalpis is found at cooler and drier conditions than Pi. evansi. Our results also show significant interspecific differences in both behavioral traits, with Pi. evansi preferring warmer, more humid conditions than Lu. longipalpis. Finally, we found that Lu. longipalpis shows greater tolerance to extreme low humidity, and that this is especially pronounced in males of the species. Conclusions: Taken together, our results suggest that temperature and humidity conditions are key aspects of the climatic niche of Lutzomyia and Pintomyia sand flies and underscore the value of integrative studies of climatic tolerance and preference in vector biology. [ABSTRACT FROM AUTHOR]

Simple Summary: Arthropods are a large and diverse group of animals, some of which are pests, while others transmit human and livestock diseases as they bite them to feed on blood. Chemical-based vector and pest control for decades has made many arthropods resistant to the chemicals used. So, there is a need to investigate other control agents, such as the biological, arthropod-killing fungus Metarhizium anisopliae, for the ability to infect and kill human and livestock disease-transmitting arthropods. In this study, we tested if the fungus M. anisopliae infects and kills mosquitoes, tsetse flies, and ticks. This was performed by finding out how long mosquitoes lived after being infected with fungus spores, as well as the amount of fungus spores suitable to lead to their death. The same optimal concentration of fungus that killed mosquitoes also successfully killed tsetse flies and ticks. We recommend that the fungus be formulated in a suitable concentration of 109 spores/mL and its ability to kill mosquitoes, tsetse flies, and ticks be confirmed in the field. This would lead to the development of a fungal formulation that can be sprayed on livestock such as cattle, for the exposure of multiple blood-feeding and disease-transmitting arthropods at the same time, to impact their survival. Arthropod vectors are responsible for a multitude of human and animal diseases affecting poor communities in sub-Saharan Africa. Their control still relies on chemical agents, despite growing evidence of insecticide resistance and environmental health concerns. Biorational agents, such as the entomopathogenic fungus Metarhizium anisopliae, might be an alternative for vector control. Recently, the M. anisopliae isolate ICIPE 7 has been developed into a commercial product in Kenya for control of ticks on cattle. We were interested in assessing the potential of controlling not only ticks but also disease-transmitting mosquitoes and tsetse flies using cattle as blood hosts, with the aim of developing a product for integrated vector management. Laboratory bioassays were carried out with M. anisopliae, isolate ICIPE 7 and isolate ICIPE 30, to compare efficacy against laboratory-reared Anopheles arabiensis. ICIPE 7 was further tested against wild Glossina fuscipes and Rhipicephalus spp. Dose–response tests were implemented, period of mosquito exposure was evaluated for effects on time to death, and the number of spores attached to exposed vectors was assessed. Exposure to 109 spores/mL of ICIPE 7 for 10 min resulted in a similar mortality of An. arabiensis as exposure to ICIPE 30, albeit at a slower rate (12 vs. 8 days). The same ICIPE 7 concentration also resulted in mortalities of tsetse flies (LT50: 16 days), tick nymphs (LT50: 11 days), and adult ticks (LT50: 20 days). Mosquito mortality was dose-dependent, with decreasing LT50 of 8 days at a concentration of 106 spores/mL to 6 days at 1010 spores/mL. Exposure period did not modulate the outcome, 1 min of exposure still resulted in mortality, and spore attachment to vectors was dose-dependent. The laboratory bioassays confirmed that ICIPE 7 has the potential to infect and cause mortality to the three exposed arthropods, though at slower rate, thus requiring further validation under field conditions. [ABSTRACT FROM AUTHOR]

Emerging and re‐emerging pathogens often stem from zoonotic origins, cycling between humans and animals, and are frequently vectored and maintained by hematophagous arthropod vectors. The efficiency by which these disease agents are successfully transmitted between vertebrate hosts is influenced by many factors, including the host on which a vector feeds. The Lyme disease bacterium Borrelia burgdorferi sensu lato has adapted to survive in complex host environments, vectored by Ixodes ticks, and maintained in multiple vertebrate hosts. The versatility of Lyme borreliae in disparate host milieus is a compelling platform to investigate mechanisms dictating pathogen transmission through complex networks of vertebrates and ticks. Squamata, one of the most diverse clade of extant reptiles, is comprised primarily of lizards, many of which are readily fed upon by Ixodes ticks. Yet, lizards are one of the least studied taxa at risk of contributing to the transmission and life cycle maintenance of Lyme borreliae. In this review, we summarize the current evidence, spanning from field surveillance to laboratory infection studies, supporting their contributions to Lyme borreliae circulation. We also summarize the current understanding of divergent lizard immune responses that may explain the underlying molecular mechanisms to confer Lyme spirochete survival in vertebrate hosts. This review offers a critical perspective on potential enzootic cycles existing between lizard‐tick‐Borrelia interactions and highlights the importance of an eco‐immunology lens for zoonotic pathogen transmission studies. [ABSTRACT FROM AUTHOR]

Antimicrobial resistance (AMR) is a health issue common to all One Health domains. Scientific understanding of what drives AMR and how it spreads is continually expanding. One such dimension of this expanding base of knowledge is the role wildlife populations play as reservoirs and spreaders of AMR. Indirect and direct sharing of resistant pathogens between wildlife and domestic animals occurs in a variety of ways across both the natural and built environment. Though AMR is found across much of the Earth's biome naturally, elevated levels in wildlife are largely attributed to the use of antimicrobials in human and veterinary medicine, along with other uses of antimicrobials in human industry. On the basis of current research, wildlife species appear to be net recipients of AMR overall. However, wildlife can carry and spread AMR across individual ecosystems and to other ecosystems via water, soil, arthropod vectors, and several other routes of conveyance. In addition to creating potential health issues for wildlife animals themselves, this potentially poses risks for both companion and production animals. This is especially due to urban/suburban and rural wildlife, respectively. If health practitioners and other stakeholders are adequately aware, measures can be taken to reduce risks across each interface discussed. The companion Currents in One Health article by Vezeau and Kahn, AJVR, June 2024, addresses in further detail the many wildlife reservoirs of AMR that are currently identified, as well as directions for further research. [ABSTRACT FROM AUTHOR]

In the early 2000s, matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) emerged as a performant and relevant tool for identifying micro-organisms. Since then, it has become practically essential for identifying bacteria in microbiological diagnostic laboratories. In the last decade, it was successfully applied for arthropod identification, allowing researchers to distinguish vectors from non-vectors of infectious diseases. However, identification failures are not rare, hampering its wide use. Failure is generally attributed either to the absence of respective counter species MS spectra in the database or to the insufficient quality of query MS spectra (i.e., lower intensity and diversity of MS peaks detected). To avoid matching errors due to non-compliant spectra, the development of a strategy for detecting and excluding outlier MS profiles became compulsory. To this end, we created MSProfileR, an R package leading to a bioinformatics tool through a simple installation, integrating a control quality system of MS spectra and an analysis pipeline including peak detection and MS spectra comparisons. MSProfileR can also add metadata concerning the sample that the spectra are derived from. MSProfileR has been developed in the R environment and offers a user-friendly web interface using the R Shiny framework. It is available on Microsoft Windows as a web browser application by simple navigation using the link of the package on Github v.3.10.0. MSProfileR is therefore accessible to non-computer specialists and is freely available to the scientific community. We evaluated MSProfileR using two datasets including exclusively MS spectra from arthropods. In addition to coherent sample classification, outlier MS spectra were detected in each dataset confirming the value of MSProfileR. [ABSTRACT FROM AUTHOR]

Dengue virus (DENV) is a continuing global threat that puts half of the world's population at risk for infection. This mosquito-transmitted virus is endemic in over 100 countries. When a mosquito takes a bloodmeal, virus is deposited into the epidermal and dermal layers of human skin, infecting a variety of permissive cells, including keratinocytes, Langerhans cells, macrophages, dermal dendritic cells, fibroblasts, and mast cells. In response to infection, the skin deploys an array of defense mechanisms to inhibit viral replication and prevent dissemination. Antimicrobial peptides, pattern recognition receptors, and cytokines induce a signaling cascade to increase transcription and translation of pro-inflammatory and antiviral genes. Paradoxically, this inflammatory environment recruits skin-resident mononuclear cells that become infected and migrate out of the skin, spreading virus throughout the host. The details of the viral–host interactions in the cutaneous microenvironment remain unclear, partly due to the limited body of research focusing on DENV in human skin. This review will summarize the functional role of human skin, the cutaneous innate immune response to DENV, the contribution of the arthropod vector, and the models used to study DENV interactions in the cutaneous environment. [ABSTRACT FROM AUTHOR]

Yunnan province in China shares its borders with three neighboring countries: Myanmar, Vietnam, and Laos. The region is characterized by a diverse climate and is known to be a suitable habitat for various arthropods, including midges which are notorious for transmitting diseases which pose significant health burdens affecting both human and animal health. A total of 431,100 midges were collected from 15 different locations in the border region of Yunnan province from 2015 to 2020. These midges were divided into 37 groups according to the collection year and sampling site. These 37 groups of midges were then homogenized to extract nucleic acid. Metatranscriptomics were used to analyze their viromes. Based on the obtained cytochrome C oxidase I gene (COI) sequences, three genera were identified, including one species of Forcipomyia, one species of Dasyhelea, and twenty-five species of Culicoides. We identified a total of 3199 viruses in five orders and 12 families, including 1305 single-stranded positive-stranded RNA viruses (+ssRNA) in two orders and seven families, 175 single-stranded negative-stranded RNA viruses (−ssRNA) in two orders and one family, and 1719 double-stranded RNA viruses in five families. Six arboviruses of economic importance were identified, namely Banna virus (BAV), Japanese encephalitis virus (JEV), Akabane virus (AKV), Bluetongue virus (BTV), Tibetan circovirus (TIBOV), and Epizootic hemorrhagic disease virus (EHDV), all of which are capable, to varying extents, of causing disease in humans and/or animals. The survey sites in this study basically covered the current distribution area of midges in Yunnan province, which helps to predict the geographic expansion of midge species. The complexity and diversity of the viral spectrum carried by midges identified in the study calls for more in-depth research, which can be utilized to monitor arthropod vectors and to predict the emergence and spread of zoonoses and animal epidemics, which is of great significance for the control of vector-borne diseases. [ABSTRACT FROM AUTHOR]

The study of herbivorous arthropod vectors of plant pathogens has been a subdiscipline within entomology for more than a century. It was recognized as a unique field with the establishment of a Subsection (Cc) in the Entomological Society of America (ESA) from 1953 through 2007. During that period, work in the field expanded from an initial emphasis on management of vector-borne plant pathogens to include biology of the pathosystems. Since 2007, when ESA reorganized the subsections within the society, work on herbivorous vectors of plant pathogens has continued to grow. This article briefly summarizes the work in this field prior to, during, and after the ESA Subsection Cc era. We identify and describe 4 research areas that have characterized the field since 2007: Molecular mechanisms of vector–plant interactions, managing vectors and pathogen transmission in agriculture, illuminating the ecology of vectors and pathogens outside of crops, and pathogen manipulation of host phenotypes and vector behavior. We then identify 10 frontiers and prospects for the field in the coming years that build on these 4 research areas, ranging from molecular and cellular aspects to ramifications for managed and natural ecosystems. We also examine trends in funding and professional opportunities for scientists working on herbivorous vectors and pathogens. Finally, we renew the call for greater integration of work addressing vector-borne plant, animal, and human pathogens due to fundamental similarities in their biology and importance for human well-being within an expanded understanding of the "One Health" paradigm, which currently emphasizes human and animal health. [ABSTRACT FROM AUTHOR]

• Multi-omics analysis of effect of Subolesin knockdown on the regulome of tick cells. • Results support a key role for Subolesin in the tick cell regulome. • Differential proteins provide insights into vaccine protective mechanisms. • Differential proteins suggest candidate tick protective antigens. Ticks as obligate blood-feeding arthropod vectors of pathogenic viruses, bacteria, protozoa and helminths associated with prevalent tick-borne diseases (TBDs) worldwide. These arthropods constitute the second vector after mosquitoes that transmit pathogens to humans and the first vector in domestic animals. Vaccines constitute the safest and more effective approach to control tick infestations and TBDs, but research is needed to identify new antigens and improve vaccine formulations. The tick protein Subolesin (Sub) is a well-known vaccine protective antigen with a highly conserved sequence at both gene and protein levels in the Ixodidae and among arthropods and vertebrates. In this study, transcriptomics and proteomics analyses were conducted together with graph theory data analysis in wild type and Sub knockdown (KD) tick ISE6 cells in order to identify and characterize the functional implications of Sub in tick cells. The results support a key role for Sub in the regulation of gene expression in ticks and the relevance of this antigen in vaccine development against ticks and TBDs. Proteins with differential representation in response to Sub KD provide insights into vaccine protective mechanisms and candidate tick protective antigens. [ABSTRACT FROM AUTHOR]

Ticks are the main arthropod vector of pathogens to humans and livestock in the British Isles. Despite their role as a vector of disease, many aspects of tick biology, ecology, and microbial association are poorly understood. To address this, we investigated the composition of the microbiome of adult and nymphal Ixodes ricinus ticks. The ticks were collected on a dairy farm in Southwest England and RNA extracted for whole genome sequencing. Sequences were detected from a range of microorganisms, particularly tick-associated viruses, bacteria, and nematodes. A majority of the viruses were attributed to phlebo-like and nairo-like virus groups, demonstrating a high degree of homology with the sequences present in I. ricinus from mainland Europe. A virus sharing a high sequence identity with Chimay rhabdovirus, previously identified in ticks from Belgium, was detected. Further investigations of I. ricinus ticks collected from additional sites in England and Wales also identified Chimay rhabdovirus viral RNA with varying prevalence in all tick populations. This suggests that Chimay rhabdovirus has a wide distribution and highlights the need for an extended exploration of the tick microbiome in the United Kingdom (UK). [ABSTRACT FROM AUTHOR]

Background and Aim: Toxoplasma gondii and Trypanosoma evansi, the zoonotic protozoa responsible for toxoplasmosis and trypanosomiasis, are significant threats to the productivity and financial stability of livestock farming. T. gondii can be transmitted horizontally through ingestion of fecal oocysts and T. evansi through arthropod vectors. In addition, both species can be transmitted from mother to fetus through the placenta. This study aimed to assess the molecular prevalence of T. gondii and T. evansi transplacental-transmitted protozoans and to identify the epidemiological risk factors in recently calved female cattle across Phayao, Thailand. Materials and Methods: We collected 106 bovine placentas from beef and dairy cow full-term pregnancies in Phayao, Thailand. T. gondii and T. evansi DNA were detected using targeted B1 gene and expression site-associated gene (ESAG) species-specific polymerase chain reaction (PCR), respectively. Results: Forty-three placentas were positive for T. gondii B1 PCR, whereas only one was positive for T. evansi ESAG PCR, resulting in an overall prevalence of transplacental-transmitted protozoan infection of 41.5% (44/106). The prevalence of T. gondii and T. evansi was 40.6% (43/106) and 0.9% (1/106), respectively. No significant correlation was found between T. gondii infection and various risk factors, including locality, age, and cattle type. Conclusion: The prevalence of transplacental-transmitted protozoan T. gondii infection was high among female cattle in Phayao, Thailand, whereas the prevalence of T. evansi infection was notably lower. Although the conventional modes of transmission differ between these two parasites, the transplacental transmission of T. evansi and especially T. gondii may play a crucial role in the persistence of these protozoan species in this area. [ABSTRACT FROM AUTHOR]

Viticulture worldwide is challenged by grapevine trunk diseases (GTDs). Involvement of arthropods in the dissemination process of GTD pathogens, notably esca pathogens, is indicated after detection of associated pathogens on arthropod exoskeletons, and demonstration of transmission under artificial conditions. The present study is the first to quantify spore loads via qPCR of the esca-relevant pathogen Phaeomoniella chlamydospora on arthropods collected in German vineyards, i.e., European earwigs (Forficula auricularia), ants (Formicidae), and two species of jumping spiders (Marpissa muscosa and Synageles venator). Quantification of spore loads showed acquisition on exoskeletons, but most arthropods carried only low amounts. The mycobiome on earwig exoskeletons was described for the first time to reveal involvement of earwigs in the dispersal of GTDs in general. Metabarcoding data support the potential risk of earwigs as vectors for predominantly Pa. chlamydospora and possibly Eutypa lata (causative agent of Eutypa dieback), as respective operational taxonomical unit (OTU) assigned genera had relative abundances of 6.6% and 2.8% in total reads, even though with great variation between samples. Seven further GTD-related genera were present at a very low level. As various factors influence the successful transmission of GTD pathogens, we hypothesize that arthropods might irregularly act as direct vectors. Our results highlight the importance of minimizing and protecting pruning wounds in the field. [ABSTRACT FROM AUTHOR]

For over a century, vector ecology has been a mainstay of vector-borne disease control. Much of this research has focused on the sensory ecology of blood-feeding arthropods (black flies, mosquitoes, ticks, etc.) with terrestrial vertebrate hosts. Of particular interest are the cues and sensory systems that drive host seeking and host feeding behaviours as they are critical for a vector to locate and feed from a host. An important yet overlooked component of arthropod vector ecology are the phenotypic changes observed in infected vectors that increase disease transmission. While our fundamental understanding of sensory mechanisms in disease vectors has drastically increased due to recent advances in genome engineering, for example, the advent of CRISPR-Cas9, and high-throughput "big data" approaches (genomics, proteomics, transcriptomics, etc.), we still do not know if and how parasites manipulate vector behaviour. Here, we review the latest research on arthropod vector sensory systems and propose key mechanisms that disease agents may alter to increase transmission. [ABSTRACT FROM AUTHOR]

Purpose: Flea-borne rickettsioses, collectively referred to as a term for etiological agents Rickettsia felis, Rickettsia typhi, and RFLOs (R. felis-like organisms), has become a public health concern around the world, specifically in the United States. Due to a shared arthropod vector (the cat flea) and clinical signs, discriminating between Rickettsia species has proven difficult. While the effects of microbial coinfections in the vector can result in antagonistic or synergistic interrelationships, subsequently altering potential human exposure and disease, the impact of bacterial interactions within flea populations remains poorly defined. Methods: In this study, in vitro and in vivo systems were utilized to assess rickettsial interactions in arthropods. Results: Coinfection of both R. felis and R. typhi within a tick-derived cell line indicated that the two species could infect the same cell, but distinct growth kinetics led to reduced R. felis growth over time, regardless of infection order. Sequential flea coinfections revealed the vector could acquire both Rickettsia spp. and sustain coinfection for up to 2 weeks, but rickettsial loads in coinfected fleas and feces were altered during coinfection. Conclusion: Altered rickettsial loads during coinfection suggest R. felis and R. typhi interactions may enhance the transmission potential of either agent. Thus, this study provides a functional foundation to disentangle transmission events propelled by complex interspecies relationships during vector coinfections. [ABSTRACT FROM AUTHOR]

The purpose of this study was to investigate the bacterial communities of biting midges and ticks collected from three sites in the Poyang Lake area, namely, Qunlu Practice Base, Peach Blossom Garden, and Huangtong Animal Husbandry, and whether vectors carry any bacterial pathogens that may cause diseases to humans, to provide scientific basis for prospective pathogen discovery and disease prevention and control. Using a metataxonomics approach in concert with full-length 16S rRNA gene sequencing and operational phylogenetic unit (OPU) analysis, we characterized the species-level microbial community structure of two important vector species, biting midges and ticks, including 33 arthropod samples comprising 3,885 individuals, collected around Poyang Lake. A total of 662 OPUs were classified in biting midges, including 195 known species and 373 potentially new species, and 618 OPUs were classified in ticks, including 217 known species and 326 potentially new species. Surprisingly, OPUs with potentially pathogenicity were detected in both arthropod vectors, with 66 known species of biting midges reported to carry potential pathogens, including Asaia lannensis and Rickettsia bellii, compared to 50 in ticks, such as Acinetobacter Iwoffii and Staphylococcus sciuri. We found that Proteobacteria was the most dominant group in both midges and ticks. Furthermore, the outcomes demonstrated that the microbiota of midges and ticks tend to be governed by a few highly abundant bacteria. Pantoea sp7 was predominant in biting midges, while Coxiella sp1 was enriched in ticks. Meanwhile, Coxiella spp., which may be essential for the survival of Haemaphysalis longicornis Neumann, were detected in all tick samples. The identification of dominant species and pathogens of biting midges and ticks in this study serves to broaden our knowledge associated to microbes of arthropod vectors. Biting midges and ticks carry large numbers of known and potentially novel bacteria, and carry a wide range of potentially pathogenic bacteria, which may pose a risk of infection to humans and animals. The microbial communities of midges and ticks tend to be dominated by a few highly abundant bacteria. [ABSTRACT FROM AUTHOR]

Hard ticks (Acari: Ixodidae) are the economically and ecologically most important blood-sucking arthropod vectors that can transmit disease agents under temperate climate. In this group, the highest number of species (currently nearing 270) belongs to the genus Ixodes. For this review, more than 400 papers related to this genus in the context of Russia were checked for data on the host records, locations of collection, as well as ecology of assigned tick species. This monograph compensates for the lack of a similarly comprehensive English-language overview of Ixodes species in the region of Russia for nearly half century, and also makes a large set of data easily available for international readers, which is especially important if the original source is difficult to access from outside this country. In addition, the data from a significant number of papers on this topic available only in the Russian language are made accessible through this work. [ABSTRACT FROM AUTHOR]

The Bunyavirales order includes at least fourteen families with diverse but related viruses, which are transmitted to vertebrate hosts by arthropod or rodent vectors. These viruses are responsible for an increasing number of outbreaks worldwide and represent a threat to public health. Infection in humans can be asymptomatic, or it may present with a range of conditions from a mild, febrile illness to severe hemorrhagic syndromes and/or neurological complications. There is a need to develop safe and effective vaccines, a process requiring better understanding of the adaptive immune responses involved during infection. This review highlights the most recent findings regarding T cell and antibody responses to the five Bunyavirales families with known human pathogens (Peribunyaviridae, Phenuiviridae, Hantaviridae, Nairoviridae, and Arenaviridae). Future studies that define and characterize mechanistic correlates of protection against Bunyavirales infections or disease will help inform the development of effective vaccines. [ABSTRACT FROM AUTHOR]

Invasions of arthropod vectors and viruses are the main factors associated with emerging plant viral diseases. The presence of the Banana bunchy top virus (BBTV, genus Babuvirus), an aphid‐transmitted virus responsible for the banana bunchy top disease (BBTD), was first confirmed in 2008 in the South region of Cameroon. This study reports on surveys over 14 years to determine the status of BBTV spread and virus diversity in Cameroon. A total of 544 fields extending through 81 districts in 7 regions were surveyed in 5 phases: (1) 2009–10, (2) 2012, (3) 2013–14, (4) 2016–17, and (5) 2022. BBTV was detected in 36 sites, all located in the Ambam district in the South region, with an incidence in the virus‐affected fields ranging from 5% to 40%, with an average incidence of 14.8%. The findings indicate BBTV expansion from the location of first detection in 2008 to about 4–25 km in all directions, with the virus spread range of about 700 km2, as of the last survey in 2022. Phylogenetic analysis using complete nucleotide sequences of the BBTV‐R and BBTV‐S gene aligned Cameroon isolates with the sub‐Saharan Africa subgroup of the Pacific‐Indian Oceans (PIO) group of BBTV isolates, suggesting a likely virus invasion from neighbouring central African countries where BBTV presence had been reported in the 1980s. Knowledge of BBTV distribution provided through the detection and delimiting surveys has contributed to the efficient targeting of interventions to limit the expansion of an emerging virus threat to banana production in Cameroon. [ABSTRACT FROM AUTHOR]

Plant viruses are a group of intracellular pathogens that persistently threaten global food security. Significant advances in plant virology have been achieved by Chinese scientists over the last 20 years, including basic research and technologies for preventing and controlling plant viral diseases. Here, we review these milestones and advances, including the identification of new crop‐infecting viruses, dissection of pathogenic mechanisms of multiple viruses, examination of multilayered interactions among viruses, their host plants, and virus‐transmitting arthropod vectors, and in‐depth interrogation of plant‐encoded resistance and susceptibility determinants. Notably, various plant virus‐based vectors have also been successfully developed for gene function studies and target gene expression in plants. We also recommend future plant virology studies in China. [ABSTRACT FROM AUTHOR]

Bovine papillomatosis is an infectious viral condition with cutaneous oncogenic characteristics. The disease is caused by bovine papillomavirus. It is transmitted by vertical spreading, arthropod vectors, and direct skin contact. Understanding the type of tumor, its clinical stage, and anticipated biological behaviors are crucial factors in the surgical oncology approach. A year-old Sokoto Gudali Heifer weighing approximately 80kg was presented to the Veterinary Clinic Sokoto with complaints of head rashes that spread to other parts of the body. On clinical examination, there were numerous, varying-sized cauliflower-like outgrowths with offensive odor and fly swarm. Cutaneous bovine papillomatosis was diagnosed based on clinical findings and supported by histopathology, and the Heifer was scheduled for marginal resection of the tumor. The surgery was successfully conducted; the Heifer was discharged two weeks after the surgery. Marginal resection approach was used in this case report and it involves the complete removal of a tumor leaving only a microscopic lesion, and ivermectin injection serves as a successful adjunct therapy in the treatment of cutaneous bovine papillomatosis. Different levels of aggressiveness should be taken into consideration when managing this type of tumor. [ABSTRACT FROM AUTHOR]

Mosquitoes are responsible for the transmission of numerous viruses of global health significance. The term "vector competence" describes the intrinsic ability of an arthropod vector to transmit an infectious agent. Prior to transmission, the mosquito itself presents a complex and hostile environment through which a virus must transit to ensure propagation and transmission to the next host. Viruses imbibed in an infectious blood meal must pass in and out of the mosquito midgut, traffic through the body cavity or hemocoel, invade the salivary glands, and be expelled with the saliva when the vector takes a subsequent blood meal. Viruses encounter physical, cellular, microbial, and immunological barriers, which are influenced by the genetic background of the mosquito vector as well as environmental conditions. Collectively, these factors place significant selective pressure on the virus that impact its evolution and transmission. Here, we provide an overview of the current state of the field in understanding the mosquitospecific factors that underpin vector competence and how each of these mechanisms may influence virus evolution. [ABSTRACT FROM AUTHOR]

Background: The blacklegged tick, Ixodes scapularis, transmits most vector-borne diseases in the US. It vectors seven pathogens of public health relevance, including the emerging human pathogen Anaplasma phagocytophilum. Nevertheless, it remains critically understudied compared to other arthropod vectors. Ixodes scapularis releases a variety of molecules that assist in the modulation of host responses. Recently, it was found that extracellular vesicles (EVs) carry several of these molecules and may impact microbial transmission to the mammalian host. EV biogenesis has been studied in mammalian systems and is relatively well understood, but the molecular players important for the formation and secretion of EVs in arthropods of public health relevance remain elusive. RabGTPases are among the major molecular players in mammalian EV biogenesis. They influence membrane identity and vesicle budding, uncoating, and motility. Methods: Using BLAST, an in silico pathway for EV biogenesis in ticks was re-constructed. We identified Rab27 for further study. EVs were collected from ISE6 tick cells after knocking down rab27 to examine its role in tick EV biogenesis. Ixodes scapularis nymphs were injected with small interfering RNAs to knock down rab27 and then fed on naïve and A. phagocytophilum-infected mice to explore the importance of rab27 in tick feeding and bacterial acquisition. Results: Our BLAST analysis identified several of the proteins involved in EV biogenesis in ticks, including Rab27. We show that silencing rab27 in I. scapularis impacts tick fitness. Additionally, ticks acquire less A. phagocytophilum after rab27 silencing. Experiments in the tick ISE6 cell line show that silencing of rab27 causes a distinct range profile of tick EVs, indicating that Rab27 is needed to regulate EV biogenesis. Conclusions: Rab27 is needed for successful tick feeding and may be important for acquiring A. phagocytophilum during a blood meal. Additionally, silencing rab27 in tick cells results in a shift of extracellular vesicle size. Overall, we have observed that Rab27 plays a key role in tick EV biogenesis and the tripartite interactions among the vector, the mammalian host, and a microbe it encounters. [ABSTRACT FROM AUTHOR]

ABSTRACT Ticks are increasingly important vectors of human and agricultural diseases. While many studies have focused on tick-borne bacteria, far less is known about tick-associated viruses and their roles in public health or tick physiology. To address this, we investigated patterns of bacterial and viral communities across two field populations of western black-legged ticks (Ixodes pacificus). Through metatranscriptomic analysis of 100 individual ticks, we quantified taxon prevalence, abundance, and co-occurrence with other members of the tick microbiome. In addition to commonly found tick-associated microbes, we assembled 11 novel RNA virus genomes from Rhabdoviridae, Chuviridae, Picornaviridae, Phenuiviridae, Reoviridae, Solemovidiae, Narnaviridae and two highly divergent RNA virus genomes lacking sequence similarity to any known viral families. We experimentally verified the presence of these in I. pacificus ticks across several life stages. We also unexpectedly identified numerous virus-like transcripts that are likely encoded by tick genomic DNA, and which are distinct from known endogenous viral element-mediated immunity pathways in invertebrates. Taken together, our work reveals that I. pacificus ticks carry a greater diversity of viruses than previously appreciated, in some cases resulting in evolutionarily acquired virus-like transcripts. Our findings highlight how pervasive and intimate tick–virus interactions are, with major implications for both the fundamental biology and vectorial capacity of I. pacificus ticks.IMPORTANCETicks are increasingly important vectors of disease, particularly in the United States where expanding tick ranges and intrusion into previously wild areas has resulted in increasing human exposure to ticks. Emerging human pathogens have been identified in ticks at an increasing rate, and yet little is known about the full community of microbes circulating in various tick species, a crucial first step to understanding how they interact with each and their tick host, as well as their ability to cause disease in humans. We investigated the bacterial and viral communities of the Western blacklegged tick in California and found 11 previously uncharacterized viruses circulating in this population.

ABSTRACT Transmission of Yersinia pestis by fleas depends on the formation of condensed bacterial aggregates embedded within a gel-like matrix that localizes to the proventricular valve in the flea foregut and interferes with normal blood feeding. This is essentially a bacterial biofilm phenomenon, which at its end stage requires the production of a Y. pestis exopolysaccharide that bridges the bacteria together in a cohesive, dense biofilm that completely blocks the proventriculus. However, bacterial aggregates are evident within an hour after a flea ingests Y. pestis, and the bacterial exopolysaccharide is not required for this process. In this study, we characterized the biochemical composition of the initial aggregates and demonstrated that the yersinia murine toxin (Ymt), a Y. pestis phospholipase D, greatly enhances rapid aggregation following infected mouse blood meals. The matrix of the bacterial aggregates is complex, containing large amounts of protein and lipid (particularly cholesterol) derived from the flea’s blood meal. A similar incidence of proventricular aggregation occurred after fleas ingested whole blood or serum containing Y. pestis, and intact, viable bacteria were not required. The initial aggregation of Y. pestis in the flea gut is likely due to a spontaneous physical process termed depletion aggregation that occurs commonly in environments with high concentrations of polymers or other macromolecules and particles such as bacteria. The initial aggregation sets up subsequent binding aggregation mediated by the bacterially produced exopolysaccharide and mature biofilm that results in proventricular blockage and efficient flea-borne transmission.IMPORTANCEYersinia pestis, the bacterial agent of plague, is maintained in nature in mammal-flea-mammal transmission cycles. After a flea feeds on a mammal with septicemic plague, the bacteria rapidly coalesce in the flea’s digestive tract to form dense aggregates enveloped in a viscous matrix that often localizes to the foregut. This represents the initial stage of biofilm development that potentiates transmission of Y. pestis when the flea later bites a new host. The rapid aggregation likely occurs via a depletion-aggregation mechanism, a non-canonical first step of bacterial biofilm development. We found that the biofilm matrix is largely composed of host blood proteins and lipids, particularly cholesterol, and that the enzymatic activity of a Y. pestis phospholipase D (Ymt) enhances the initial aggregation. Y. pestis transmitted by flea bite is likely associated with this host-derived matrix, which may initially shield the bacteria from recognition by the host's intradermal innate immune response.

Abstract Background Vector sand fly colonies are a critical component of studies aimed at improving the understanding of the neglected tropical disease leishmaniasis and alleviating its global impact. However, among laboratory-colonized arthropod vectors of infectious diseases, the labor-intensive nature of sand fly rearing coupled with the low number of colonies worldwide has generally discouraged the widespread use of sand flies in laboratory settings. Among the different factors associated with the low productivity of sand fly colonies, mite infestations are a significant factor. Sand fly colonies are prone to infestation by mites, and the physical interactions between sand flies and mites and metabolites have a negative impact on sand fly larval development. Methods Mites were collected from sand fly larval rearing pots and morphologically identified using taxonomic keys. Upon identification, they were photographed with a scanning electron microscope. Several mite control measures were adopted in two different laboratories, one at the Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases-National Institutes of Health (Rockville, MD, USA), and the other at the University of Calgary (Calgary, AB, Canada). Results The mite species associated with sand fly colonies in the two laboratories were morphologically identified as Tyrophagus sp. and Stratiolaelaps scimitus. While complete eradication of mites in sand fly colonies is considered unrealistic, drastically reducing their population has been associated with higher sand fly productivity. Conclusions We report a case of detrimental interaction between sand flies and Tyrophagus sp. and S. scimitus in a closed laboratory sand fly colony, discuss their impact on sand fly production and provide guidelines for limiting the mite population size in a closed laboratory colony leading to improved sand fly yields. Graphical abstract

Syphilis is becoming an increasingly concerning sexually transmitted infection in the primary care setting with a precipitous rise in cases in the USA over the past decade according to the CDC surveillance data. This rise in cases is particularly relevant in military medicine as the greatest increase in cases is among adults in their 20s. Nodular syphilis is a rare presentation of the secondary stage of syphilis, and contrary to the well-known maculopapular rash seen with syphilis infection, little is known about effective treatment of nodular manifestations of the disease. We present a case of a 54-year-old HIV-positive man with nodular secondary syphilis effectively treated with an empiric 2-week course of oral doxycycline. Initial differential diagnosis included erythema nodosum, arthropod vector disease, skin infection, and erythema elevatum diutinum. Biopsy demonstrated granulomatous dermatitis, and serology revealed positive Treponema pallidum antibodies with a rapid plasma reagin of 1:256, confirming the diagnosis of secondary syphilis with granulomatous dermatitis. This case indicates that clinicians should consider this unusual cutaneous presentation of secondary syphilis when evaluating patients with nodular skin lesions, especially in high-risk individuals. [ABSTRACT FROM AUTHOR]

Background: Vector sand fly colonies are a critical component of studies aimed at improving the understanding of the neglected tropical disease leishmaniasis and alleviating its global impact. However, among laboratory-colonized arthropod vectors of infectious diseases, the labor-intensive nature of sand fly rearing coupled with the low number of colonies worldwide has generally discouraged the widespread use of sand flies in laboratory settings. Among the different factors associated with the low productivity of sand fly colonies, mite infestations are a significant factor. Sand fly colonies are prone to infestation by mites, and the physical interactions between sand flies and mites and metabolites have a negative impact on sand fly larval development. Methods: Mites were collected from sand fly larval rearing pots and morphologically identified using taxonomic keys. Upon identification, they were photographed with a scanning electron microscope. Several mite control measures were adopted in two different laboratories, one at the Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases-National Institutes of Health (Rockville, MD, USA), and the other at the University of Calgary (Calgary, AB, Canada). Results: The mite species associated with sand fly colonies in the two laboratories were morphologically identified as Tyrophagus sp. and Stratiolaelaps scimitus. While complete eradication of mites in sand fly colonies is considered unrealistic, drastically reducing their population has been associated with higher sand fly productivity. Conclusions: We report a case of detrimental interaction between sand flies and Tyrophagus sp. and S. scimitus in a closed laboratory sand fly colony, discuss their impact on sand fly production and provide guidelines for limiting the mite population size in a closed laboratory colony leading to improved sand fly yields. [ABSTRACT FROM AUTHOR]

Simple Summary: This review summarizes the available information on the ex-vivo survival of the porcine reproductive and respiratory syndrome virus (PRRSV), the cause of porcine reproductive and respiratory syndrome in pigs. We highlight the possible role of different fomites and environmental sources in indirect transmission of this virus to susceptible hosts. The number of studies on this topic is limited but fomites (porous, non-porous, and liquid), insects, people, and pork meat have been studied, mostly under experimental conditions. Porcine reproductive and respiratory syndrome (PRRS) is one of the most economically important diseases of swine, with losses due to poor reproductive performance and high piglet and growing pig mortality. Transmission of porcine reproductive and respiratory syndrome virus (PRRSV) may occur by both direct and indirect routes; the latter includes exposure to PRRSV-contaminated fomites, aerosols, and arthropod vectors. This review has collected available data on the ex-vivo environmental stability and persistence of PRRSV in an effort to highlight important sources of the virus and to determine the role of environmental conditions on the stability of the virus, especially temperature. The ex-vivo settings include fomites (solid, porous, and liquid fomites), insects, people, and pork meat, as well as the role of environmental conditions on the stability of the virus, especially temperature. [ABSTRACT FROM AUTHOR]

Amblyomma sculptum is a species of public health interest because it is associated with the transmission of the bacteria that causes Brazilian Spotted Fever (BSF). The use of repellents on humans is a prophylactic measure widely used to provide protection against a series of arthropod vectors, including mosquitoes and ticks. However, in Brazil, the effectiveness of commercial repellents against A. sculptum is little known. Therefore, it is necessary to carry out specific studies to evaluate the repellency of these commercial products, registered for use against mosquitoes, against the star tick. The main goal of the present work was to evaluate the effectiveness of six commercial repellents against A. sculptum. Unfed nymphs, aged between two and eight weeks, were tested against products based on DEET (OFF!® and Repelex®), Icaridin (Exposis® and SBP®), and IR3535 (Johnsons and Henlau). Three bioassays were conducted to evaluate tick behavior: (i) filter paper, (ii) fingertip, and (iii) field. All bases tested showed high repellent activity, differing significantly (p < 0.05) from the control. It was observed the formulation with DEET resulted in the best results in the filter paper bioassay. In the fingertip bioassay, the DEET base repelled a greater number of ticks compared to Icaridin. In the field bioassay, there was no significant difference between the Icaridin base and DEET, and both formulations differed from the control (p < 0.05). The six formulations tested showed significant percentages of repellency against ticks; however, for the fingertip and field bioassays, the products OFF!®, Repelex®, and Exposis® were tested as they showed better performance in the filter paper test. OFF!® showed the best percentage of repellency (100%), followed by Repelex® (96.8%), and Exposis® (93.1%), considering the two-hour period of the bioassay-field-test. Proving the effectiveness of repellents on the market against A. sculptum presented in this study is crucial, since this is the main ectoparasite of humans that can transmit Rickettsia rickettsii when infected. The effectiveness of commercial insect repellents against other tick species that parasitize humans can also be explored. [ABSTRACT FROM AUTHOR]

Bartonella spp. are intracellular hemotropic bacteria primarily transmitted by arthropod vectors to various mammalian hosts, including humans. In this study, we conducted a survey on wild populations of sigmodontine rodents, Akodon azarae and Oxymycterus rufus, inhabiting the Paraná River delta region. The study involved eight grids organized in a crossed 2 × 2 design, where four of the grids were exposed to cattle while the other four were not, and four grids were located in implanted forest while the remaining four were in natural grasslands. Our objective was to examine whether the occurrence of Bartonella spp. in rodents was associated with silvopastoral activities (cattle raising associated with timber production) conducted in the region. Additionally, we evaluated the associations between Bartonella infection and other environmental and host factors. We present compelling evidence of a significant positive association between Bartonella prevalence and the presence of implanted forests and cattle. Furthermore, we identified the presence of a Bartonella genotype related to the pathogen Bartonella rochalimaea, infecting both A. azarae and Ox. rufus. These findings suggest that anthropogenic land-use changes, particularly the development of silvopastoral practices in the region, may disrupt the dynamics of Bartonella. [ABSTRACT FROM AUTHOR]

West Nile virus (WNV) is the most significant arbovirus in the United States in terms of both morbidity and mortality. West Nile exists in a complex transmission cycle between avian hosts and the arthropod vector, Culex spp. mosquitoes. Human spillover events occur when humans are bitten by an infected mosquito and predicting these rates of infection and therefore the risk to humans may be associated with fluctuations in environmental conditions. In this study, we evaluate the hydrological and meteorological drivers associated with mosquito biology and viral development to determine if these associations can be used to forecast seasonal mosquito infection rates with WNV in the Coachella Valley of California. We developed and tested a spatially resolved ensemble forecast model of the WNV mosquito infection rate in the Coachella Valley using 17 years of mosquito surveillance data and North American Land Data Assimilation System‐2 environmental data. Our multi‐model inference system indicated that the combination of a cooler and dryer winter, followed by a wetter and warmer spring, and a cooler than normal summer was most predictive of the prevalence of West Nile positive mosquitoes in the Coachella Valley. The ability to make accurate early season predictions of West Nile risk has the potential to allow local abatement districts and public health entities to implement early season interventions such as targeted adulticiding and public health messaging before human transmission occurs. Such early and targeted interventions could better mitigate the risk of WNV to humans. Plain Language Summary: West Nile virus (WNV) is the most significant arbovirus in the United States and is transmitted seasonally by mosquitoes. Humans are most at risk when they are in close proximity to infected mosquitoes. Predicting the risk to humans is not straightforward. In this study, we use deviations in climate associated with mosquito biology and viral development to forecast seasonal West Nile risk in the Coachella Valley of California. We developed a statistical model of WNV transmission in the Coachella Valley using 17 years of mosquito surveillance data and environmental data. Our model indicated that the combination of a cooler and dryer winter followed by a wetter and warmer spring and a cooler than normal summer was the combination of environmental events most associated with West Nile positive mosquitoes in the Coachella Valley. The ability to make accurate early season predictions of West Nile risk could assist local public health entities implement early season interventions to better mitigate the risk of WNV to humans in the Coachella Valley. Key Points: Environmentally informed West Nile virus (WNV) forecast modelOur forecast shows that a dry, cool winter, followed by a wet, warm spring, and a cool summer promotes WNVEarly season forecasts are a potential decision tool to inform public health and mosquito abatement intervention [ABSTRACT FROM AUTHOR]

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Bartonelloses are neglected emerging infectious diseases caused by facultatively intracellular bacteria transmitted between vertebrate hosts by various arthropod vectors. The highest diversity of Bartonella species has been identified in rodents. Within this study we focused on the edible dormouse (Glis glis), a rodent with unique life-history traits that often enters households and whose possible role in the epidemiology of Bartonella infections had been previously unknown. We identified and cultivated two distinct Bartonella sub(species) significantly diverging from previously described species, which were characterized using growth characteristics, biochemical tests, and various molecular techniques including also proteomics. Two novel (sub)species were described: Bartonella grahamii subsp. shimonis subsp. nov. and Bartonella gliris sp. nov. We sequenced two individual strains per each described (sub)species. During exploratory genomic analyses comparing two genotypes ultimately belonging to the same species, both factually and most importantly even spatiotemporally, we noticed unexpectedly significant structural variation between them. We found that most of the detected structural variants could be explained either by prophage excision or integration. Based on a detailed study of one such event, we argue that prophage deletion represents the most probable explanation of the observed phenomena. Moreover, in one strain of Bartonella grahamii subsp. shimonis subsp. nov. we identified a deletion related to Bartonella Adhesin A, a major pathogenicity factor that modulates bacteria-host interactions. Altogether, our results suggest that even a limited number of passages induced sufficient selective pressure to promote significant changes at the level of the genome. [ABSTRACT FROM AUTHOR]