Parasites & Vectors最新文献

Background: Effective mosquito control in urban areas requires understanding of how climatic, ecological and socioeconomic factors shape vector abundance. However, most studies use linear or opaque models that overlook nonlinear relationships between environmental conditions and Aedes albopictus density. These complex associations remain insufficiently characterized in highly urbanized settings, where interacting environmental and human factors jointly influence mosquito habitats.

Methods: We trained a random forest model, an XGBoost model with a default squared-error objective and an XGBoost model with a Poisson count objective using adult Aedes albopictus monitoring data collected across Shanghai from April to November 2023. Model performance was evaluated with RMSE, MAE, R² and Poisson deviance, and temporally blocked cross-validation was applied to assess temporal generalizability. SHAP analysis was used to interpret variable importance and contribution patterns. To examine operational relevance, we additionally evaluated hotspot localization accuracy using July 2024 data.

Results: On the independent test set, the XGBoost-Poisson model achieved the best overall accuracy (R² = 0.73, Poisson deviance = 4.52). SHAP analysis identified the 14-day temperature lag as the dominant predictor, followed by a slight negative population density and compulsory completion of education. Precipitation and NDVI showed smaller positive contributions. Age structure variables exhibited nonlinear trends-with an inverted-U shape for children, a declining pattern for older adults and a shallow U shape for building height. By site type, mosquito density tended to be higher near schools, livestock sheds and office areas and lower in residential, farmhouse, park and hospital environments. Under temporally blocked cross-validation, the model retained moderate temporal generalization. In out-of-time hotspot validation, the top 10% of sites captured 41-50% of hotspots, rising to 60-68% at 25% coverage, suggesting moderate spatial localization.

Conclusions: The framework identified key environmental and socioeconomic drivers of Aedes albopictus density in Shanghai. Despite moderate temporal generalization, it provides interpretable, fine-scale insights to guide targeted vector control and inform urban mosquito management in dense metropolitan settings. Future research should validate the framework across additional seasons and diverse urban contexts, incorporate finer environmental and infrastructural data and enhance uncertainty quantification for improved interpretive robustness.

Background: India aims to eliminate malaria by 2030; however, a thorough understanding of the current biology and behavior of vector species will facilitate the efforts. Vector species often alter their biting and resting behaviors in response to long-term chemical control measures, posing significant challenges to ongoing vector control interventions. Therefore, it is essential to investigate and update our knowledge of the bionomics of malaria vectors in the current context.

Methods: This study was carried out across 14 districts in eight Indian states between 2021 and 2023, employing various entomological techniques. Anopheles mosquito species were tested for human blood meal preference and Plasmodium infection using polymerase chain reaction (PCR). Insecticide susceptibility status was assessed according to World Health Organization (WHO) protocols, and key metrics, such as degree of exophily, trap density, human biting rate (HBR), and man-hour density (MHD), were determined to understand mosquito abundance and behavior.

Results: Anopheles culicifacies, a major malaria vector species, was found in all study states. The highest indoor MHD of this species was 11.95, recorded in the Kanker district of Chhattisgarh, whereas 27.16 was the highest outdoor MHD as observed in the Bareilly district of Uttar Pradesh. In Assam and Tripura, Anopheles minimus exhibited differential resting behavior, whereas An. baimaii was found to be exophilic in Kokrajhar, Udalguri, and South Tripura. An. stephensi showed endophilic behavior with an indoor MHD of 4.36 in Barmer. An. minimus exhibited high anthropophagic behavior, with a human blood index of 0.94 in South Tripura. A high sporozoite infection rate was observed in An. baimaii (5.88) compared with the other vector species. An. culicifacies was found to be resistant to alpha-cypermethrin (0.05%) in the Jagdalpur and Kanker districts, with possible resistance in Barmer study sites, and resistant to deltamethrin (0.05%) in Kanker, Surendranagar, and Dahod. An. stephensi showed resistance to multiple insecticides in the North Goa.

Conclusions: An. culicifacies was prevalent in all eight study states, with a higher abundance in Kanker and Bareilly. Changes in the resting behavior of An. minimus in Tripura, and insecticide resistance that has developed in An. culicifacies and An. stephensi against pyrethroids poses a significant concern. The findings of this study will aid in implementing effective vector control strategies in India's pre-elimination efforts against malaria.

Background: Chagas disease has historically been linked to triatomines and rural areas. However, urban infestations by one of its vectors, Triatoma infestans, are increasingly being reported. Urbanization is reshaping vectorial transmission patterns of this disease, creating new collective health challenges. To provide evidence on the eco-epidemiological status of Chagas in the metropolitan region of San Juan, Argentina, this study integrates data collected on biomedical, epidemiological, socioenvironmental, and territorial factors.

Methods: We conducted a cross-sectional analysis of 432 urban houses for infestations by Triatoma infestans and infection of these vectors with Trypanosoma cruzi, complemented by environmental, sociodemographic, and human practices surveys. Additionally, we carried out information, education, and communication (IEC) activities to engage with and become acquainted with the community. The IEC activities included immersive virtual reality experiences, community dialogue, and educational games in public spaces.

Results: Our study revealed a house infestation prevalence with T. infestans of 10% both indoors and in the houses' outdoor spaces; T. cruzi infection was not detectable in any of the insects. Wind was identified as an environmental factor associated with house infestation, as was the presence of chicken coops, in addition to the condition of the houses (structural condition, such as cracks and poor plastering, and how the outdoor space of the houses was used, e.g., for the storage of objects that had accumulated over time). A combination of sociodemographic and environmental factors influenced T. infestans infestation prevalence. The IEC activities reached over 150 community members and promoted a dialogue about Chagas disease and vector control. The virtual reality and educational games encouraged strong youth engagement, and the media campaign helped raise awareness and visibility of the issue in the region.

Conclusions: The infestation prevalence of T. infestans in the urban area of San Juan highlights the need for urban-specific control strategies that differ from those used in rural settings. The key findings of this study, such as chicken coops being infestation hotspots and the importance of wind direction, and the unique urban context (high-density housing, a territorial institutional presence, and community networks), enable us to recognize opportunities for integrated, multi-actor control frameworks that actively involve communities.

Background: Malaria diagnosis plays a key role in case management, control, and elimination strategies. miLab™ is a digital microscopy with a fully integrated, sample-to-result approach, providing automated microscopic analysis of Plasmodium parasites and providing parasitemia levels of samples. It uses a deep learning model, a subfield of artificial intelligence (AI) that can differentiate from red blood cells that are infected with the malaria parasite from noninfected cells in blood smears. The aim of this study is to assess the performance of miLab™ microscopy for malaria diagnosis, in comparison with conventional microscopy and nested-multiplex malaria polymerase chain reaction (NM-PCR), in a malaria reference laboratory in a nonendemic country.

Methods: From 2021 to 2024, 400 samples were analyzed prospectively using automated miLab™ microscopy, with NM-PCR and conventional microscopy as reference methods.

Results: The comparison between the miLab™ device and thin blood smear microscopy showed substantial concordance (90.8%), with a kappa coefficient of 0.8 and sensitivity and specificity values of 92.1% and 89.4%, respectively. The comparison of parasite density showed a significant correlation (correlation coefficient of 0.77), although the parasite counts estimated by the miLab™ device were 11.6% lower than those estimated by conventional microscopy. The sensitivity and specificity values of the miLab™ platform when compared with those obtained by NM-PCR were 62.8% and 95.4%, respectively; with a concordance value of 68.9% (kappa coefficient 0.4). Of P. falciparum infections identified by NM-PCR, 63.4% were accurately identified, and this figure increased to 95.7% if excluding negative results. One P. vivax, three P. ovale, and one P. malariae infections identified by NM-PCR were correctly classified by the miLab™ platform only after expert review of initial "review needed" results.

Conclusions: miLab™ automated microscopy was as sensitive as conventional microscopy but without the need for expert microscopists and with shorter time to results. It is a valuable toolkit for malaria diagnosis in nonendemic settings; however, improvements are required in terms of species identification and parasite quantification.

Background: A major challenge to global vector control efforts is the increasing resistance of Aedes mosquitoes to conventional insecticides. Since they are the main vectors of dengue, Zika, and chikungunya, sustainable and environmentally friendly approaches are essential for vector control. Attractive toxic sugar baits (ATSBs) take advantage of mosquitoes' propensity for sugar and can offer an alternative strategy. However, further research is needed to investigate the performance of ATSBs, especially in determining and assessing attractant combinations that might increase mosquito attraction and feeding efficiency.

Methods: This study examines the feeding preferences of Ae. aegypti and Ae. albopictus for several fruit-based ATSB formulations. We employed three assays of attractants: mango alone, banana alone, and a combined mango-banana formulation, as well as a control set. Three replicates of each species at a 50% dosage of each fruit extract were evaluated.

Results: The findings indicate that combining fruit sources enhances mosquito attraction, since there is a statistically significant preference for the mixed fruit formulation (1:1) compared with the single-fruit attractants (P < 0.05). However, there were no significant differences in the feeding preferences between the males and the females, indicating that the treatment effect is equal for both genders.

Conclusions: This study contributes to the ongoing advancement of sustainable and efficient vector control strategies by demonstrating the enhanced attractiveness of mixed-fruit formulations, which offer environmentally safe methods for managing Aedes mosquito vectors and arboviral diseases.

Background: Despite widespread implementation of malaria control measures, including insecticide-treated nets (ITNs), indoor residual spraying (IRS), and seasonal malaria chemoprevention (SMC), malaria remains a major public health concern in Burkina Faso. The persistence of transmission is often attributed to increasing insecticide resistance in Anopheles gambiae sensu lato and drug resistance in Plasmodium spp. However, additional factors, such as climatic variability, ecological change, and shifts in vector species composition, may also play a role. This study investigated the geographic distribution of secondary malaria vectors and assessed their potential role in sustaining transmission at the national scale.

Methods: Between 2023 and 2024, mosquito surveys were conducted across the three main ecological zones of Burkina Faso using human landing catches (HLC) and pyrethroid spray catches (PSC). Secondary vector species were identified morphologically. Molecular assays were used to detect Plasmodium infections and characterize blood-meal origins. Climatic data from national meteorological stations were analyzed to explore associations between environmental variables and species abundance.

Results: A total of 1718 Anopheles mosquitoes (excluding An. gambiae s.l.) were collected, 688 in 2023 and 1030 in 2024. Five species were identified: Anopheles nili, An. coustani, An. pharoensis, An. funestus, and An. rufipes. Most specimens originated from the Sudan zone, with An. nili overwhelmingly dominant (87.5% of captures in 2023; 93% in 2024). Rainfall and, to a lesser extent, temperature were significantly associated with species abundance at several sites. Most mosquitoes were collected outdoors and showed strong anthropophilic tendencies. Molecular screening detected Plasmodium falciparum in all species except An. funestus. Infection was highest in Diébougou, with sporadic positive samples in An. coustani and An. nili across both years.

Conclusions: Secondary vectors, particularly An. nili and An. coustani, appear to play an increasingly important role in malaria transmission in Burkina Faso. Their outdoor and sometimes opportunistic feeding behaviors highlight limitations of current indoor-focused interventions. These findings underscore the need to broaden surveillance and adapt vector control strategies to include secondary vector species in high-transmission settings.

Background: The brown bear (Ursus arctos) is an apex predator with significant ecological importance and serves as a valuable indicator species for monitoring parasitic burdens in forest ecosystems. Owing to its complex ecology and varied diet, this species may play a key role in the life cycle of numerous pathogens, including cestodes of the genus Taenia, such as the recently described Taenia arctos. Among the potential intermediate hosts for T. arctos is the moose (Alces alces), a species sporadically present in northern Romania, where its habitat may overlap with that of U. arctos. In this context, the present study aimed to identify and molecularly characterize cestodes isolated from the small intestines of U. arctos.

Methods: Between May 2022 and December 2024, small intestines from 91 U. arctos individuals were collected across 16 counties in Romania. Biological samples were preserved by freezing and analyzed using both classical methods (macroscopic and microscopic examination) and molecular biology techniques (through amplification and sequencing of mitochondrial gene fragments, cox1 and 12S rRNA).

Results: Out of the 91 samples analyzed, only 1 specimen tested positive for an adult cestode (prevalence 1.1%). Genetic analysis confirmed its identification as T. arctos, a species not previously reported in Romania.

Conclusions: This study represents the first molecular identification of T. arctos in U. arctos in southeastern Europe, thereby extending the known geographic range of the parasite. The findings may indicate that trophic interactions compatible with the life cycle of T. arctos occur in this area, although the evidence is limited to a single detection.

Background: Mixed strongyle infections represent the most prevalent equine parasitosis and can result in life-threatening disease, especially in young horses. Species involvement and pathogenesis of this parasitosis are poorly understood, and data on foals and broodmares are notably lacking.

Methods: In a longitudinal study undertaken in 2022 in Germany, individual faecal samples (n = 497) and metadata were collected for naturally infected foals and broodmares (n = 48) kept under conventional husbandry conditions. Nematode infections were detected coproscopically via the Mini-FLOTAC method. In a subset of strongyle egg-positive samples (n = 46), species were identified using cytochrome c oxidase subunit I deep amplicon sequencing. Species prevalence, richness, and alpha and beta diversity were compared between foals and mares.

Results: Overall, 22.2% of the foal samples and 10.2% of the mare samples were strongyle egg positive (eggs per gram > 5). Parascaris spp. were only detected in foals (15.1%). Strongyloides westeri was detected in one foal sample. Strongyle egg detection increased in likelihood with each additional sample timepoint (OR = 1.42, P < 0.001) and with ascarid egg detection (OR = 6.49, P < 0.001), while last anthelmintic treatment with pyrantel decreased the odds of detecting eggs (OR = 0.12, P = 0.002). Deep amplicon sequencing detected 16 species of small strongyles but no large strongyle species. Cylicostephanus goldi, Cylicostephanus minutus operational taxonomic unit II and Cylicocyclus ashworthi were significantly more prevalent in mares (P < 0.05), while Cylicostephanus calicatus operational taxonomic unit II was more prevalent in foals (P < 0.01). Mares showed a significantly higher amplicon sequence-variant-based richness (Chao 1 index, P < 0.001) and diversity (inverse Simpson index, P < 0.01) than foals. Group (foals vs. mares) explained some of the variance in beta diversity, according to permutational multivariate ANOVA. Co-infection with Parascaris spp. did not affect strongyle community composition in the foals. Bray-Curtis and Jaccard distance (dissimilarity) plots showed separate clusters for mares and foals, with some overlap and a moderate model fit.

Conclusions: Cytochrome oxidase-based characterization of mixed strongyle infections revealed strongyle community differences between broodmares and foals. Possible age associations were identified for four species of small strongyles, including two cryptic species. Low overall strongyle prevalence and egg-shedding intensity, non-random sampling and differences in anthelmintic treatment schemes limited the statistical power of this study.