Summer seasonal prevalence of Culicoides species from pre-alpine areas in Switzerland

Ultrastructural and morphological observations of the external and internal structures of the adult midge Culicoides grisescens (Diptera: Ceratopogonidae)

The external and internal structures of adult males and females of Culicoides grisescens Edwards were examined using scanning electron microscopy (SEM) and tissue sectioning techniques. Specimens were collected from Qilian Mountain National Park in Qinghai Province, China. The ultrastructure and morphology of the compound eyes, antennae, maxillary palpi, spermathecae, genitalia, and other structural features both male and female adults of C. grisescens are described. Significant morphological differences between the two sexes were observed. The female has a pair of large mandibles with 16 teeth arranged in two rows. The first row contains 16 teeth, while the second row is located near the terminal teeth at the lower part. In contrast, the male mandibles have 2 to 3 teeth, totaling over 20, with a slender structure and small teeth distributed near the center at the terminal end of the mandibles. The tip of the male tongue is narrower and triangular than in shape compared to the female. Additionally, there are significant differences in the shape of the antennae and the types of antennal sensilla between males and females. This study also observed that the middle lobe of the male masculine stem is V-shaped, and the terminal end of the masculine lateral process is bifurcated, featuring 5 to 7 slender, finger-like branches. These unique morphological structures are useful for distinguishing male Culicoides from each other. For the first time, this paper describes the internal structures of this species, including histological sections of the digestive, nervous, respiratory, and reproductive systems. The findings presented herein provide both visual and descriptive details for the systematic taxonomic study of Ceratopogonidae, highlighting their significant economic and medical importance.

Local investigation into the role of Culicoides species diversity (Diptera: Ceratopogonidae) in recurrent horse dermatitis cases in southwest France

BACKGROUND

Insect bite hypersensitivity in horses ("sweet itch") is a common pruritic, chronic, seasonal, and recurrent dermatitis affecting approximately 10% of horses in France and is a major concern for the horse industry and private owners. This dermatitis results from an allergic reaction to the saliva of specific biting flies (Diptera: Nematocera), primarily from the Culicoides genus. Given the frequent occurrence of this health problem and the limited investigation in France, we conducted a field survey in the vicinity of a riding stable in southwestern France with a reported chronic case of recurrent horse dermatitis to (i) characterize the Culicoides species associated with horse populations and (ii) estimate the relative abundance of the different species identified based on the trapping site location.

METHODS

For this purpose, three Onderstepoort Veterinary Institute (OVI) traps were set up for one night once a week, from mid-June to the end of July 2022, the known adult peak activity period. Traps were placed either indoors or outdoors at horse facilities.

RESULTS

Culicoides obsoletus/scoticus were more abundant (58.3%), followed by C. circumscriptus (12.1%), C. nubeculosus (11.5%), C. punctatus (5.6%), C. festivipennis (3.8%), C. pulicaris (2.3%), C. riethi (2.3%), C. parroti (2.2%), and the remaining species, C. lupicaris, C. dewulfi, C. brunnicans, C. flavipulicaris, and C. picturatus, collectively representing only 1.4%. Importantly, C. obsoletus/scoticus and C. circumscriptus were found indoors in notable proportions (54% and 11.4% of captures, respectively).

CONCLUSIONS

The findings highlight the continuous exposure of horses to Culicoides bites during the warm season, including at night and indoors, from C. obsoletus/scoticus, but also including low-impact species like C. punctatus and C. pulicaris. This underlines the need for ongoing research and surveillance.

Evolution of MALDI-TOF MS Profiles from Lice and Fleas Preserved in Alcohol over Time

MALDI-TOF is now considered a relevant tool for the identification of arthropods, including lice and fleas. However, the duration and conditions of storage, such as in ethanol, which is frequently used to preserve these ectoparasites, could impede their classification. The purpose of the present study was to assess the stability of MS profiles from Pediculus humanus corporis lice and Ctenocephalides felis fleas preserved in alcohol from one to four years and kinetically submitted to MALDI-TOF MS. A total of 469 cephalothoraxes from lice (n = 170) and fleas (n = 299) were tested. The reproducibility of the MS profiles was estimated based on the log score values (LSVs) obtained for query profiles compared to the reference profiles included in the MS database. Only MS spectra from P. humanus corporis and C. felis stored in alcohol for less than one year were included in the reference MS database. Approximately 75% of MS spectra from lice (75.2%, 94/125) and fleas (74.4%, 122/164) specimens stored in alcohol for 12 to 48 months, queried against the reference MS database, obtained relevant identification. An accurate analysis revealed a significant decrease in the proportion of identification for both species stored for more than 22 months in alcohol. It was hypothesized that incomplete drying was responsible for MS spectra variations. Then, 45 lice and 60 fleas were subjected to longer drying periods from 12 to 24 h. The increase in the drying period improved the proportion of relevant identification for lice (95%) and fleas (80%). This study highlighted that a correct rate of identification by MS could be obtained for lice and fleas preserved in alcohol for up to four years on the condition that the drying period was sufficiently long for accurate identification.

Risk Factors and Spatiotemporal Distribution of Lumpy Skin Disease Occurrence in the Asian Continent during 2012-2022: An Ecological Niche Model

Lumpy skin disease (LSD) is an emerging transboundary infectious disease of animals with high morbidity and low mortality rates. The infection occurs in cattle, buffalo, and some closely related wild animals, with cattle and buffalo showing higher susceptibility than other species. The primary mode of disease transmission is the mechanical dispersion of bloodsucking insects. The disease symptoms, including animal fur damage, weight loss, decline in milk production, infertility, and miscarriage, lead to huge economic losses in regions and countries with LSD outbreaks. The present study aimed to analyze the incidence data of LSD in the Asian continent from January 2012 to September 2022, identify spatiotemporal clusters and risk factors of the disease, and establish a maximum entropy ecological niche model to predict high-risk areas for disease outbreaks. The studied variables included bioclimatic factors, land type, and population density. Following the screening process, 12 variables were included in the maximum entropy model. Among them, the variable contribution rates of cattle density, land cover, isothermality, buffalo density, and maximum temperature of the warmest month were 53.8%, 10.9%, 9.2%, 8.9%, and 8%, respectively. Accounting for more than 90% of the total variable contribution rate, these five variables were considered to be the important influencing factors of LSD outbreaks. According to the results, nine spatiotemporal clusters approximately matched the high-risk areas predicted by the model. The Caucasus region of Russia; the Russian border areas of Kazakhstan, Turkey, Syria, Lebanon, Palestine, and Israel; and the western regions of Iran, India, and Southeast Asia were predicted to be high-risk areas. Thus, this study provides the spatiotemporal clusters, risk factors, and high-risk areas of LSD outbreaks in the Asian continent, which can help formulate more effective disease prevention and control policies.

Matrix-assisted laser desorption ionization-time-of-flight mass spectrometry in veterinary medicine: Recent advances (2019-present)

Matrix-assisted laser desorption ionization-time-of-flight (MALDI-TOF) mass spectrometry (MS) has become a valuable laboratory tool for rapid diagnostics, research, and exploration in veterinary medicine. While instrument acquisition costs are high for the technology, cost per sample is very low, the method requires minimal sample preparation, and analysis is easily conducted by end-users requiring minimal training. Matrix-assisted laser desorption ionization-time-of-flight MS has found widespread application for the rapid identification of microorganisms, diagnosis of dermatophytes and parasites, protein/lipid profiling, molecular diagnostics, and the technique demonstrates significant promise for 2D chemical mapping of tissue sections collected postmortem. In this review, an overview of the MALDI-TOF technique will be reported and manuscripts outlining current uses of the technology for veterinary science since 2019 will be summarized. The article concludes by discussing gaps in knowledge and areas of future growth.