Medical and Veterinary Entomology最新文献

Vector-borne diseases pose significant global threats to both human and animal health, and their impacts are expected to intensify with ongoing climate change. Understanding the ecological and environmental drivers of these diseases is essential for developing effective surveillance and control strategies. Central to this is knowledge of the distributions of vectors and hosts, and how these may shift in response to environmental changes. In this study, we present a generalisable framework for predicting the current and future distributions of vectors and wildlife hosts using correlative modelling approaches. We integrate these predictions with data on livestock and human populations to inform the potential risk of West Nile virus (WNV) establishment and exposure in the United Kingdom. Currently absent from the United Kingdom, WNV is an orthoflavivirus maintained in a natural transmission cycle between mosquitoes and birds. Spillover into incidental hosts such as humans and horses can result in febrile illness, with severe cases leading to encephalitis and death. Our findings identify regions at elevated risk of WNV establishment where competent avian hosts and mosquito vectors are likely to co-occur and where infected vectors may interact with spillover hosts. We also explore how these risk patterns may evolve by 2100 under different environmental scenarios. Across all scenarios, risk is projected to increase in the south-east of the United Kingdom and decline in northern regions. This work demonstrates how modelling current and future vector and host distributions can inform risk assessments for emerging vector-borne diseases. Such insights are critical for guiding policy decisions and enhancing preparedness for disease incursions in a changing environment.

Flesh flies (Sarcophagidae), along with blow flies, are among the first colonizers of vertebrate cadavers, including human corpses. Their early colonization and rapid development frequently result in the collection of flesh fly larvae as evidence during crime scene investigations or autopsies. Despite their regular occurrence and confirmed forensic importance, the species-level identification of sarcophagid larvae remains challenging. To address this, the morphology of the first-instar larva of three common and widespread European species with confirmed forensic relevance—Sarcophaga africa, S. caerulescens, S. melanura—was revised. Material was analysed using both light microscopy and scanning electron microscopy (SEM). Taxonomically important characters were identified in the pseudocephalon, the facial mask, mouthhooks and basal sclerite of the cephaloskeleton, and the distribution and shape of spines and papillae of the anal plate. The results are compared with previous descriptions, and an identification key is presented for the first-instar larvae of forensically relevant flesh fly species of central and northern Europe.

Ecological niche models (ENMs) and species distribution models (SDMs) are essential tools for investigating the ecological requirements and geographic distributions of species at multiple spatial and temporal scales. While these modelling techniques have been employed across various taxonomic groups to explore ecology, evolution and biogeography, their application to ticks and tick-borne pathogens (TBPs) has yielded valuable—though not yet conclusive—perspectives for understanding epidemiology and pathogen transmission risk. Advances in research on these topics necessitate a review to determine whether there is consistency in the conceptual and methodological implementation of these approaches, as well as to identify needs for improvement and adaptation to more informative alternatives. Here, we aim to review the state of the art in the use of these concepts and tools in the study of tick species and TBPs worldwide to provide a clear understanding of their theoretical and methodological foundations, study topics, involved species, variables, geographic resolutions, applications of model outputs and thematic evolution. We conducted a formal literature review of 158 publications in the period from 1997 to May 2024, along with bibliometric and scientometric analyses. Results indicate that the main topic of study resides in the prediction of current and future potential geographic distribution, and most of the work has been carried out only for nine genera of ticks, with major focus on species belonging to the family Ixodidae and those affecting human health. Borrelia burgdorferi Johnson et al. (Spirochaetales: Borreliaceae) is the most explored pathogen. Studies have mostly used bioclimatic variables, but some studies also incorporate topographic variables from local to global scales, with resolutions ranging from 30 m to 80 km. Although ENM and SDM in ticks and TBPs have been routinely used, very few have been validated in the field, and their projections are not used in epidemiological monitoring. Over 60% of the studies do not report sufficient methodological information for replication. We also detected imprecise usage of the terms ENM and SDM, which are often used interchangeably. This lack of conceptual clarity impedes the adequate treatment of both ecological niches and geographic distributions, hindering advancement in this research field worldwide. We recommend including species of the family Argasidae in future studies to analyse their ecological requirements and potential distributions. These species have been poorly studied despite being vectors of pathogens causing diseases with medical and veterinary importance (e.g., relapsing fever and spirochetosis). Lastly, we identify key areas for improvement—from biogeographical knowledge gaps to the use of modern sampling methods, algorithms and hypotheses—that would enhance the application of these concepts and modelling techniques.

Aedes aegypti Linnaeus 1762 (Diptera: Culicidae) is the primary vector of several pathogens of public health significance. Insecticide-based preventative measures are a key component of vector-borne disease control programmes. However, widespread insecticide resistance threatens the effectiveness of current control strategies. Sarolaner, an isoxazoline insecticide, offers a novel mode of action and is primarily used for controlling ticks, fleas and mites in companion animals. This study evaluates the insecticidal efficacy of sarolaner against both laboratory-susceptible and resistant strains of Ae. aegypti through various exposure routes. In topical assays, sarolaner outperformed permethrin by >8-fold and >21-fold greater efficacy against resistant strains at 24 and 72 h, respectively. Conversely, it underperformed in susceptible strains by over 8-fold and 2-fold at the same time points. In larval assays, sarolaner exhibited >300-fold greater toxicity than spinosad at 24 and 48 h for both susceptible and resistant strains. Blood-feeding assays showed sarolaner was more toxic than ivermectin by over 17-fold and 10-fold in susceptible and resistant strains, respectively, up to 120 h. While sarolaner was less toxic than dinotefuran in resistant strains through sugar feeding, it was over 3-fold more toxic in susceptible strains. Notably, no cross-resistance was detected with dinotefuran or ivermectin through oral, sugar or blood-feeding applications, though slight cross-resistance was observed with permethrin and spinosad. This study highlights sarolaner's potential as an effective adulticide and larvicide against Ae. aegypti, supporting its further evaluation as a candidate for new chemical formulations.

As a tropical country, Colombia hosts a wide range of arthropods that can act as vectors of disease-causing pathogens, particularly those carrying hemopathogens. Ticks play a crucial role in the transmission of zoonotic pathogens, impacting both human and veterinary health. The pathogen load of ticks from wildlife is of particular concern, as it can contribute to the spillover of infectious agents to domestic animals and humans, highlighting the need for surveillance and control strategies to mitigate emerging tick-borne diseases. Therefore, this study aimed to determine the presence of microorganisms in ticks collected from wildlife in Antioquia (Colombia) through bioinformatic analysis. A prospective, cross-sectional, random, non-probabilistic, convenience-based study involving tick collection from animals in three different zones of Antioquia was conducted. Initially, vertebrate species were morphologically characterized via taxonomic keys and identification guides for amphibians, reptiles, birds, and mammals. Ticks were manually collected from these animals and preserved in absolute ethanol for later taxonomic identification. Genomic DNA was then extracted, and the resulting reads were processed through bioinformatic analysis, achieving taxonomic classification within DNA libraries of gram-positive bacteria, gram-negative bacteria, and parasites. Additionally, descriptive statistics were calculated for all variables of interest at the animal level (e.g., genus, species, sex, and age group, when applicable) and study zone. A total of 570 ticks, predominantly Amblyomma spp., were obtained from 46 host animals. Ticks from lizards presented the highest bacterial richness and diversity (based on 16S gDNA), whereas ticks from amphibians presented the lowest. Proteobacteria dominated most samples, as shown by taxonomic composition at the phylum, family, and genus levels. Ticks collected from mammals displayed lower diversity and richness than those collected from reptiles. For parasitic communities (18S gDNA), dominant eukaryotes were identified in ticks from mammals, excluding host-related taxa. Overall, lizard-associated ticks presented the most complex microbial diversity, whereas amphibian ticks were less diverse, highlighting the significant variation in microbial and parasitic communities across host species. This study highlights the microbial diversity of ticks from wild hosts in Colombia, focusing on the dominance of Francisella, Rickettsia, Aspergillus, and Penicillium. These findings underscore the need for further research on their ecological roles, transmission dynamics, and potential health risks, aiming to inform strategies to mitigate tick-borne diseases.

Culicoides (Diptera, Ceratopogonidae) biting midges serve as vectors of viruses, bacteria, filaria, and protozoans, such as dixenous avian blood parasites (Trypanosomatidae). Additionally, these insects can harbour insect-specific flagellates—monoxenous trypanosomatids—which are generally considered harmless commensals; however, in certain cases, they can increase mortality or reduce the fitness of their insect hosts. Recent studies indicate that the prevalence of trypanosomatids in wild-caught biting midges can reach up to 11.1%, while in experimentally infected individuals, infection rates can be even higher. This study explores the diversity of trypanosomatids detected in Culicoides biting midges worldwide and supplements current knowledge with new records of avian Trypanosoma occurrence in these insects from the Curonian Spit, Lithuania. Wild-caught biting midges collected in 2020–2022 using UV light traps were tested for the presence of trypanosomatids using polymerase chain reaction (PCR)-based methods. Both morphological and molecular methods were used for Culicoides species identification. Four species of Trypanosoma were determined in biting midges belonging to eight different species. Avian trypanosomes from the T. bennetti group, T. avium, and T. culicavium were detected in C. pallidicornis/subfascipennis, C. segnis, C. kibunensis, C. festivipennis, C. pictipennis, C. duddingstoni, C. impunctatus, and biting midges of the C. obsoletus group. Additionally, mammal-infecting Trypanosoma from the T. theileri group were detected in C. pictipennis. Monoxenous Herpetomonas ztiplika and Sergeia podlipaevi were found in C. obsoletus group, C. segnis, C. pallidicornis/subfascipennis, C. kibunensis, C. pictipennis, C. festivipennis, and C. impunctatus biting midges as well. This study reports, for the first time, the presence of avian Trypanosoma in C. duddingstoni females and also reviews previous research data on the prevalence of both monoxenous and dixenous trypanosomatids in different Culicoides species. Our results enhance the understanding of trypanosomatid diversity in Culicoides biting midges and update the list of Culicoides species that should be considered in research on their role as potential vectors of avian Trypanosoma.

The Ceratopogonidae family, comprising over 6000 described species, includes the genus Leptoconops, which has been understudied despite its ecological significance and biting nuisance to humans. Here, we document the presence of inland Leptoconops noei populations for the first time in Italy in an area previously considered environmentally atypical for this species. Our findings expand the known range of L. noei, traditionally confined to coastal areas, and highlight its potential to colonise diverse habitats. Interestingly, despite the thorough morphological and molecular identification of sampled individuals and their clear assignment to the species L. noei, a notable morphological variability was observed in the sensory structures of the maxillary palps, suggesting the possibility of a new morphotype or environment-driven adaptations. Phylogenetic analyses of COX1 sequences revealed negligible genetic differentiation between the newly discovered inland population and coastal populations, suggesting recent separation or gene-flow connection. These findings underscore the ecological adaptability of L. noei, which poses risks of human-biting nuisance, allergic reactions and even possible economic losses in recreative areas, in a range of locations wider than previously assumed. Additionally, this study reports the first complete mitochondrial genome for the genus Leptoconops, offering valuable genetic insights for taxonomic clarification, evolutionary studies and future research on the biology of Ceratopogonidae.

Aedes aegypti mosquitoes account for the highest number of infections among vector-borne diseases and continue to present a formidable global health challenge. Due to the nonavailability of direct treatment of dengue, vector control relies on the use of insecticides currently dominated by pyrethroids. Recurring applications of these insecticides lead to transgenerational impacts on their fitness and resistance dynamics. This study investigates the threat to vector control techniques by altered biological fitness, metabolic and molecular properties after selection with permethrin exposure. Populations of Ae. aegypti were treated with a sublethal dose of permethrin (LC₅₀) in each generation, and their resistance status, together with its effect on biological fitness and transgenerational features, were analysed. To understand the different mechanisms of resistance development, detoxifying enzyme activity, the presence of kdr mutation and cuticular thickness were also analysed. Throughout the study, a prolonged larval and pupal stage was noted with reduced fecundity and hatchability. Moreover, biochemical assays revealed a major role of cytochrome P450 monooxygenases behind permethrin resistance, which was supported by a piperonyl butoxide assay. Major kdr mutations F1534C and V1016G were also found. Overall, reduction in life traits of resistant populations may seem in favour of vector management but this may be the manipulative strategy of Ae. aegypti to divert the essential fuels away from these features and invest it towards the maintenance of insecticide resistance. Therefore, to effectively combat resistance, insecticides must be used judiciously as part of a comprehensive strategy that includes non-insecticide methods and regular surveillance.

Ticks are key ectoparasites for the One Health approach, as they are vectors of pathogens that infect humans, domestic and wild animals. The bacteria Rickettsia rickettsii and R. parkeri are the aetiological agents of tick-borne spotted fever (SF) in South America, where Amblyomma sculptum, A. aureolatum, A. ovale and A. triste are the main vectors. Studies in the medical and biological fields show that artificial intelligence, through machine learning, has great potential to assist researchers and health professionals in image identification practices. The aim of this study was to evaluate the performance of the Convolutional Neural Networks (CNN) AlexNet, ResNet-50 and MobileNetV2 for identifying tick species transmitting SF bioagents. We organised an image database with the following groups: females (368), males (458), dorsal (423), ventral (403), low resolution (328), high resolution (498) and all together (sex+position+resolution = 826), to identify the three main vectors of SF bioagents (Amblyomma aureolatum, A. ovale and A. sculptum), two other possible vectors (A. triste and A. dubitatum) and the species A. cajennense sensu stricto (s.s.), which has similar morphology to A. sculptum but no known vectorial capacity. To evaluate the network's performance, we measured accuracy, sensitivity and specificity. We used Grad-CAM to highlight the regions of the images most relevant to the predictions. CNNs achieved accuracy rates of ~90% in identifying ticks and showed sensitivities of 59%–100% according to species, sex, position or image resolution. When considering all images, both AlexNet and MobileNetV2 recorded the best sensitivity and specificity values in identifying SF vectors. The most relevant areas for classifying species varied according to algorithms. Our results support the idea of using CNNs for the automated identification of tick species transmitting SF bioagents in South America. Our database could support the development of tick identification apps to aid public health surveillance and contribute to citizen science.

In California, public health disease surveillance data for flea-borne typhus (FBT) are generated by healthcare providers and laboratories who are responsible for notifying local health jurisdictions when the disease is detected. When accounting for the associations between socioeconomic status (SES) factors (age, race and ethnicity, poverty, unemployment, housing status and land use), R. typhi reservoir host presence (e.g., rats, cats, opossums), and healthcare-seeking behaviours, it is reasonable to consider whether these factors also lead to under-reporting of FBT surveillance and distorted estimations of incidence. This study aimed to evaluate population-level associations between SES factors and FBT surveillance reporting using a Bayesian hierarchical model including a spatially autocorrelated random effect. Census tract-level covariates were sourced from the American Community Survey and Healthy Places Index (HPI). Specifying a zero-inflated Poisson distribution to FBT surveillance report counts, we estimated spatially smoothed, census tract-level estimates of FBT surveillance report rates and attributed variability in report rates to census tract characteristics. Socioeconomic advantage, as measured by the HPI, had the largest effect (IRR = 1.34 [1.07, 1.69]), corresponding to a 34% increase in FBT surveillance reporting for every point increase in HPI score for census tracts. The results herein suggest that FBT surveillance may be biased in its ascertainment of surveillance data, which may be helpful in contextualising and interpreting current trends in FBT epidemiology.