Medical and Veterinary Entomology最新文献

Aedes aegypti, the primary vector of several medically significant arboviruses-including dengue fever, yellow fever, chikungunya and Zika-was successfully eradicated from Egypt in 1963. However, since 2011, there have been increasing reports of its re-emergence, alongside dengue outbreaks in southern Egyptian governorates, raising significant public health concerns. This study aimed to model the current and future distribution of Ae. aegypti in Egypt. Local occurrence data were integrated with bioclimatic, anthropogenic and biological environmental variables to identify key factors influencing the distribution of Ae. aegypti. Maximum entropy (MaxEnt) modelling demonstrated strong predictive performance (area under the receiver operating characteristic curve [AUC] mean = 0.975; true skill statistic [TSS] mean = 0.789). The key determinants of habitat suitability were identified as human population density, annual precipitation and the normalised difference vegetation index (NDVI). Current predictions indicate that suitable habitats for Ae. aegypti are concentrated in the Nile Valley, Nile Delta, Fayoum Basin, Red Sea coast and South Sinai. Projections under future climate change scenarios suggest an expansion of suitable habitats, particularly in the Nile Delta region. By 2050, the model predicts a 61%-68% increase in suitable habitat area, with a further 64%-69% increase by 2070, depending on the future climate scenarios. These findings are crucial for informing vector control and disease prevention strategies, particularly considering Egypt's status as one of the world's leading tourist destinations.

Culicoides oxystoma Kieffer (Diptera: Ceratopogonidae) transmits many pathogens, including seven viruses, four protozoa and one nematode. This species has a wide distribution range across northern Afro-tropical, Palearctic, Australian, Indo-Malayan realms with a broad host spectrum, including cattle, buffaloes, sheep, pigs, dogs, horses and even humans. The heterogeneous nature of Culicoides' blood-feeding patterns is well documented, but the influence of various host blood meal sources on gut bacterial composition remains scant. Adult midges were collected during April (2023) by operating UV light traps in cattle, buffalo sheds and poultry farm in Purulia (India). Besides C. oxystoma, eleven Culicoides species were collected across the sheds and farm, seven of which are vectors. Culicoides liui Wirth and Hubert and C. thurmanae Wirth and Hubert are reported from India for the first time. In all the sheds, engorged females of C. oxystoma were ubiquitous. Identification of culturable gut bacteria and the host blood meal of C. oxystoma were done through the polymerase chain reaction (PCR)-based method. Blood meal analysis confirmed the following hosts: cattle, buffaloes and humans. Identification of blood meal of engorged C. oxystoma caught from poultry farm showed positive results for humans but not for birds. Among bacteria, Bacillus cereus was abundant in all of the engorged females. Bacillus paramycoides and Enterococcus faecium were identified from females feeding on cattle and buffaloes' blood, while Alcaligenes faecalis was found in the gut contents of females that fed on cattle and human blood. The gut bacteria Alcaligenes faecalis exhibited alpha haemolytic activity. In contrast, Bacillus sp., B. cereus, B. flexus, B. licheniformis, B. thuringiensis, B. paramycoides, E. faecium, Paenibacillus sp. and Pseudomonas sp. exhibited beta haemolysis. This is the first report on the composition of gut bacteria, with particular emphasis on the haemolytic bacteria of C. oxystoma with different host blood meals. The pathogenic bacteria B. cereus, B. licheniformis and A. faecalis within the females could potentially impact pathogen acquisition and increase the probability of their zoonotic transmissibility.

We investigated the mosquito community along 315 km of the Murray River, where we identified three assemblages (upper, middle, and lower river) that exhibited different patterns of species richness and diversity over 20 years. In the lower reaches (i.e., more southern latitudes), species richness and community diversity declined over time, while there was no significant change in either the middle or upper reaches. While the overall mean abundance of the common, pathogen-carrying mosquito (Diptera: Culicidae) species Aedes camptorhynchus Thomson, increased in the lower river but declined in the upper river. These results provide important information on the diversity and abundance of mosquito communities adjacent to the Murray River and highlight the importance of considering spatial and temporal variation when assessing the risk of mosquito-borne diseases. Furthermore, data presented here illustrate that there the common public narrative around increasing mosquito abundance and geographic expansion under climate change is not universally true.

Dermacentor variabilis (Say) (Acari: Ixodidae) is a vector for pathogens that can impact human and animal health. The geographic range of this species is expanding, but there are some areas with limited up-to-date information on the distribution of D. variabilis. Therefore, the objective of this study was to describe the spatial and temporal patterns of adult D. variabilis activity in central and eastern Canada. Ticks were collected from companion animals by veterinary clinic staff. Suspected locations of tick acquisition were spatially projected, and a spatial scan statistic was used to identify statistically significant clusters of frequent submissions from veterinary clinics. Submissions were categorised by calendar week to evaluate temporal trends. In total, 1198 adult D. variabilis, one nymphal D. variabilis and one Dermacentor albipictus (Packard) were collected from the provinces of Manitoba, Ontario, Quebec, New Brunswick, Nova Scotia and Prince Edward Island from April 2019 through March 2020. Peaks in adult D. variabilis submissions occurred in May and June. Most of the submissions were received from south-eastern Manitoba, eastern Ontario and central and western Nova Scotia. A statistically significant cluster of frequent submissions that included seven veterinary clinics was identified in Nova Scotia. These findings can be used to determine the locations and times at which humans and their companion animals should be considered at an increased risk of exposure to D. variabilis and the pathogens they carry.

Mass ivermectin (IVM) treatment of livestock (MITL) is under consideration as a malaria control tool as IVM-treated livestock are lethal to blood-feeding Anopheles mosquitoes. MITL is routinely used as a prophylaxis in livestock to reduce the burden and transmission of helminth infections. Recently, there has been a shift in the veterinary IVM market in Southeast Asia wherein nearly all standard IVM formulations are now co-formulated with clorsulon (CLO). CLO is used to treat the trematode liver fluke, Fasciola hepatica. Thus, the co-administration of IVM and CLO simultaneously targets multiple livestock infections. Additionally, F. hepatica frequently afflicts human populations in endemic areas, making control of F. hepatica in livestock beneficial for One Health. CLO interrupts glycolysis in F. hepatica, but its potential effect against Anopheles mosquitoes has never been evaluated. Anopheles dirus mosquitoes were blood-fed CLO across a range of concentrations (1-10,000 nM; 0.38-3807 ng/mL), and mosquito survival was monitored for 10 days. Co-feeding experiments were also performed with An. dirus blood-fed on IVM at two concentrations (4 and 6 ng/mL) without and with CLO corresponding to peak concentration in cattle (C_max) (2700 ng/mL) and five times the C_max (13,500 ng/mL), and mosquito survival was monitored for 10 days. CLO had no mosquito-lethal effect on An. dirus. The IVM and CLO co-feed experiment did not indicate any altered effect of IVM on mosquito survival when co-fed with CLO. IVM-CLO livestock co-formulations would not likely alter the Anopheles mosquito-lethal effect of MITL. The use of MITL-CLO for malaria control would have health benefits for livestock, treating helminth and liver fluke infections, and additional One Health benefits by reducing transmission risk of liver flukes to humans.

Land use and cover changes lead to fragmentation of the natural habitats of sand flies and modify the epidemiological profile of leishmaniasis. This process contributes to the infestation of adjacent rural settlements by vector sand fly species with different degrees of adaptation, promoting leishmaniasis outbreaks. This study aimed to assess land use and cover changes over a 12-year period and investigate the diversity and abundance of sand fly assemblages in the rural area of Codó, Maranhão State, Brazil. Temporal analysis of land use and cover changes was conducted using Sentinel-2 satellite imagery treated in QGIS software (free version 3.10) and classified using Orfeo Toolbox. Sand flies were sampled in alternate months between August 2022 and June 2023 using Centers for Disease Control and Prevention (CDC) light traps and white and black Shannon traps installed in peridomestic and extradomestic environments. Map images showed that the predominant land covers in 2012 and 2014 were dense and sparse vegetation, with few buildings. In 2021 and 2023, areas of sparse and dense vegetation were fragmented as new settlements were established. The entomological survey resulted in the capture of 3375 sand flies (CDC = 856, white Shannon = 650, black Shannon = 1969) belonging to 20 species. The most abundant species were Psychodopygus wellcomei Fraiha, Shaw & Lainson, 1971 (78.19%), followed by Nyssomyia whitmani (Antunes & Coutinho, 1939) (7.53%). Additionally, Ny. whitmani was the most abundant species (84.97%) in peridomestic environments, whereas Ps. wellcomei was the most abundant species (96.51%) in extradomestic environments. The sand fly assemblage was highly diverse, with a high abundance of competent vectors of Leishmania spp. These findings can promote community participation in surveillance and control efforts to prevent leishmaniasis cases.

Ticks continue to invade new regions spreading pathogens of zoonotic and veterinary importance. Diverse tick species have been reported in Ghana due to the continuous trade of livestock. In this study, ticks were collected from cattle in three sites within Southern Ghana. The 1489 ticks collected were morphologically identified and further confirmed using a molecular assay that amplifies the 660-bp segment of the mitochondrial cytochrome c oxidase subunit 1 (COI) gene. These ticks were pooled and screened for pathogens of zoonotic importance. From the 215 tick pools screened, Rickettsia DNA was detected in 34 (15.81%). Sanger sequencing revealed the occurrence of Rickettsia africae (14.42%), the causative agent of African tick-bite fever, and Rickettsia aeschlimannii (1.39%). Regular monitoring of tick populations is essential to generate data for creating effective control and preventive measures.

Culicoides biting midges adversely impact animal health through transmission of multiple orbiviruses, such as bluetongue virus (BTV). This study used light trapping data collected in the Southeastern United States for three Culicoides midge species that are confirmed or suspected BTV vectors: Culicoides insignis, Culicoides stellifer and Culicoides venustus. Midge presence datasets were combined with meteorological data and ecological data to model habitat suitability for each species. Logistic regression and machine learning models were used to generate individual species distribution models (SDMs). Results for each SDM method were combined in an ensemble model to create a distribution model for each midge species. Based on overlay analyses of livestock populations and midge suitable habitat, there is extensive overlap of cattle and goat populations and suitable habitat for C. insignis in Florida. Suitable habitat for C. stellifer intersects with cattle and goat populations in various counties in Alabama, Arkansas, the Carolinas, Florida, Georgia, Louisiana and Tennessee; and suitable habitat for C. venustus intersects with cattle and goat populations in the same states as C. stellifer, except for Florida. It is critical for orbivirus and midge surveillance to continue in the Southeastern United States as the habitat of all three midge species intersect with livestock populations.

Aedes albopictus (Skuse) and Aedes aegypti L. (Diptera: Culicidae) are invasive species known for their notable expansion capacity, which makes them relevant in the context of public health due to their role as vectors. In Argentina, these species coexist in a limited subtropical area in Northeastern part of the country. Because of the limited knowledge existing about these species in this region, the present study aims to investigate the determinants of the presence and abundance of both vectors at the larval habitat scale (presence and abundance) and neighbourhood scale (House, Container and Breteau Indices; abundance; and number of pupae). For this purpose, preimaginal stages of Ae. albopictus and Ae. aegypti were sampled in households from areas with variable urbanisation degrees (in rural, vegetated urban and non-vegetated urban) located in the province of Misiones, Argentina. The analyses considered the association with meteorological variables (temperature and precipitation), environmental variables (type of urbanisation), biotic variables (presence of predator species) and container characteristics (size and water volume). At the larval habitat scale, Ae. albopictus was associated with precipitation, temperature and rural environments. In contrast, Ae. aegypti was positively associated with urban environments and negatively with predator presence. At the neighbourhood scale, Ae. albopictus was primarily associated with precipitation and temperature, whereas Ae. aegypti showed a negative association with predator presence and positive associations with urban environments and, to a lesser degree, meteorological variables. These results indicate that in Argentina, meteorological, biotic and environmental factors have differential influences on Ae. albopictus and Ae. aegypti, underscoring the need to consider them for the development of effective public health strategies.

The nocturnal behaviour and reproduction patterns of Sarcophagidae species during the scotophase are largely unexplored for species in the Neotropical region. The aim of this study was to assess the light regimes under which females of Peckia (Peckia) chrysostoma (Wiedemann, 1830) and Peckia (Sarcodexia) lambens (Wiedemann, 1830) would larviposit and understand how these variables influence intrauterine development in these flies. The experiments were conducted in an experimental room (lux = 100) in two independent experiments: I. Larviposition test: Females mated with males of over 8 days old. II. Intrauterine development test: females over 8 days old and mated were individually isolated. Both experiments were performed under photophases (L:D) of 0:24, 6:18; 12:12; 18:6 and 24:0 for a period of 96 h. Larviposition occurred in total darkness for P. (P.) chrysostoma and P. (S.) lambens in all treatments, without significant differences among photophase treatments (p > 0.05). Photophase influenced the timing of larviposition, occurring as early as 24 h in 12:12 L:D conditions, while no larviposition was observed in the first 24 h in the 0:24 treatment for either species. The light duration significantly affected the percentage of gravid females of both species (p < 0.05), with higher percentages of gravid females in treatments of longer light duration. Females at the initial and intermediate stages of egg development were more strongly associated with treatments of continuous darkness (0:24) or short photophase (6:18), whereas females with an advanced stage of egg development were more prevalent in the 12:12 treatment. The implications of these findings for forensic entomology are profound, challenging conventional knowledge by revealing that necrophagous insects are not limited to diurnal activity patterns.