Veterinary parasitology最新文献

Buffalo fly (Haematobia irritans exigua) is recognised for its impact on cattle health, welfare, and production. It is ranked the number one endemic pest for the Australian beef cattle industry by Meat and Livestock Australia. An accurate estimation of fly numbers is essential to evaluate treatment efficacy, phenotyping of susceptible animals for genetic improvement and determining threshold levels to guide integrated pest management strategies. Traditionally, fly numbers are estimated through visual scoring which is inherently challenging as it involves estimating moving flies on a restless host. This study used digital photography and an open-source, semi-automated software package DotDotGoose to count fly numbers on individual animal images. These were then compared to the visual fly scores on the same animals. A random selection of 98 images was used and fly numbers were counted on these images in duplicate by four assessors, one experienced field researcher and three novice assessors. The fly counts on individual images were analysed for consistency and agreement and a consistency and agreement of 99 % was achieved within the four assessors, classified as excellent. The analysis further showed that visual assessments and manual visual counts by experienced assessors consistently underestimated fly numbers compared to the digital image counts. Our results suggest that a digital counting platform offers a more reliable alternative to visual scoring for buffalo fly counts. It improves accuracy and consistency and enables remote image analysis, lowers time and labour costs, and provides the potential for automated real-time monitoring and reporting of fly numbers.

Linguatulosis, caused by Linguatula serrata, commonly known as the tongue worm, primarily affects food animals and carnivores and poses a potential zoonotic risk. This systematic review and meta-analysis aimed to evaluate the global prevalence of L. serrata in these hosts. A comprehensive search identified 55 studies involving 36,242 samples from food animals and 1530 samples from carnivores across four continents. The results indicated significant variability in prevalence rates, with food animals showing a pooled prevalence of 19.1 %, and carnivores exhibiting a higher pooled prevalence of 35.5 %. The prevalence in food animals varied across species, with goats having the highest prevalence at 32.6 %, followed by camels (19.3 %), cattle (15.8 %), sheep (13.6 %), and buffalo (10.6 %). The analysis showed substantial heterogeneity (I² = 98.9 % for food animals and I² = 96.6 % for carnivores), which was influenced by factors such as host species, diagnostic methods, and sample types. Meta-regression analysis showed that host species was a significant moderator of prevalence. Sensitivity analysis and bias tests confirmed the robustness of the findings, with consistent pooled prevalence estimates and no significant publication bias. Geographic analysis showed regional differences, with particularly high prevalence rates in Bangladesh, India, Iran, and Nigeria. The study also observed temporal fluctuations, with peak prevalence recorded during 2016-2020 for food animals and 2006-2010 for carnivores. These findings emphasize the need for targeted surveillance and control strategies, particularly in regions with high transmission risks, and the importance of standardized diagnostic methods to reduce variability in future studies.

Heterobilharzia americana is a trematode parasite that causes canine schistosomiasis, a disease capable of causing significant morbidity and mortality in dogs. Reliable diagnosis is essential for limiting disease progression. This study aimed to optimize and validate a previously developed TaqMan qPCR assay for detection of H. americana DNA in feces. The assay targets a highly repetitive non-coding DNA sequence located across multiple loci within the H. americana genome. PCR optimization involved gradient thermocycling and serial dilutions to refine annealing temperature and efficiency. PCR products were cloned and sequenced to confirm target specificity. Analytical sensitivity was assessed using serial two-fold dilutions of H. americana eggs spiked into feces and matrix-free samples, with PCR detection across replicates. Diagnostic sensitivity was assessed in 111 fecal samples from infected dogs using fecal sedimentation as gold standard. Analytical and diagnostic specificities were assessed by testing 54 fecal samples containing non-target parasites and 100 fecal samples from H. americana-uninfected dogs, respectively. Target specificity was confirmed by BLAST. Assay efficiency was 107 %. Matrix-dependent analytical sensitivity was 3 eggs/g feces (100 % replicates) and 1.5 eggs/g feces (60 % replicates); matrix-free sensitivity was 3 eggs/mL in saline. Diagnostic sensitivity was 98.2 % (95 % CI: 93.7-99.8 %). Both analytical and diagnostic specificities were 100 % (95 % CI: 93.6-100 % and 96.4-100 %, respectively). The assay demonstrated low intra-assay and inter-assay variability and minimal inter-operator variability across the dilution range tested. These findings support the optimized TaqMan qPCR assay as a highly sensitive and specific tool for detecting H. americana DNA in dog feces.

Zebrafish (Danio rerio) are a widely used biomedical model and offers powerful high-throughput screening capabilities for assessing chemical bioactivity. We have previously employed adult zebrafish infected with the intestinal nematode Pseudocapillaria tomentosa to investigate nematode-microbiome interactions, nematode-promoted intestinal neoplasia, and anthelmintic drug discovery. Here we transition this model to a larval zebrafish infection infection to enable larger-scale experimentation and ultimately accelerate anthelmintic discovery. Infection conditions were optimized across 5-30 days post fertilization (dpf). The 30 dpf larvae exhibited the most robust and reproducible infections in multi-well formats, as well as the highest survival relative to younger stages. We described worm development from hatching through larval progression and maturation, addressing a major gap in foundational data with fish capillarids. Using in vitro-hatched larvae and infected larval and adult zebrafish, we documented developmental trajectories from 1 to 37 days post-exposure. Change-point analysis identified putative ecdysis transitions at the following worm lengths (mm): L1/L2 = 0.220, L2/L3 = 0.571, L3/L4 = 1.174, and L4/L5 = 1.584. Finally, we demonstrated proof-of-concept for anthelmintic screening by exposing fish to larvated eggs in the presence of emamectin benzoate (macrocyclic lactone) or fenbendazole (benzimidazole). Both compounds reduced worm burdens after 3 days, with the strongest effects at higher concentrations (0.7 µM emamectin benzoate; 0.3 µM fenbendazole). Together, these findings establishes a proof of concept for larval zebrafish infection platform which bridges the gap between in vitro and mammalian in vivo assays, enabling scalable, efficient, and biologically relevant screening for anthelmintic drug discovery.