Parasitology Research最新文献

Due to co-evolution, permanent species-specific lice and their hosts often exhibit congruent phylogenetic patterns, and to a lesser extent also congruent phylogeographic structures. However, because ectoparasites generally have smaller effective population sizes (due to their aggregated distribution), and they have a faster evolutionary rate (generation time effect), their phylogeographic structures are often more pronounced. This study investigates the phylogeographic structure of a squirrel Paraxerus cepapi and one of its louse species, Johnsonpthirus heliosciuri, sampled from eight localities in South Africa. Statistical haplotype networks derived from 51 host mitochondrial DNA control region sequences revealed a lack of geographic genetic structure among sampling sites, with most genetic variation found within populations (Φ_ST = 0.304, P < 0.05). In stark contrast, analyses of 43 louse mitochondrial COI sequences showed a clear pattern of geographic genetic structure, with most variation occurring between populations (Φ_ST = 0.797, P < 0.05). Nuclear Eukaryotic Elongation Factor 1 (EF1) data revealed no geographic structure in either species. The lack of phylogeographic congruence between host and louse, as well as between mitochondrial and nuclear markers, is likely due to stochastic differences in the evolutionary rates of host and parasite DNA. In this study, the species-specific permanent parasite acted as a biological proxy, or a 'magnifying glass', for host phylogeography. The louse mitochondrial DNA data suggest that recent anthropogenic habitat fragmentation may indeed be limiting squirrel movement across the landscape.

Traditional methods for studying digenetic trematode populations involve collecting the snail first intermediate hosts and either shedding larval cercariae or dissecting the snails. Because larval trematodes can be difficult to identify based on morphology alone, these methods are often supplemented with DNA sequencing. This approach can be labour-intensive, and environmentally disruptive. Metabarcoding of environmental DNA (eDNA) or cercariometry (counting of cercariae in water) samples offers an alternative method to simplify this process without negatively affecting the trematode community through the removal of parasites and hosts from the environment. Through ongoing trematode research in central Alberta, Canada, we have documented 102 trematode species infecting multiple snail species and have developed a database of sequences using several DNA barcoding genes. To understand how the trematode community composition derived from metabarcoding compares to a snail infection baseline, we examined the trematode species richness detected by each method. We also established a 16 S rDNA database using representative sequences to align our metabarcoding datasets with others in the field. We found no significant difference between eDNA and cercariometry samples regarding the ability of either method to estimate pooled trematode species richness, but cercariometry detected more species than eDNA when trematode richness was compared between sites. However, snail collections predicted lower species richness than both molecular methods. These findings indicate that the combination of these methods result in enhanced characterization of the trematode community. As more researchers adopt 16 S rDNA for digenetic trematode studies, metabarcoding will become an increasingly valuable tool for trematode surveillance and diversity assessments.

This report describes the case of a 28-year-old woman, who presented with a two-week history of severe ocular pain and photophobia in her right eye. She was a soft contact lens wearer with no history of ocular trauma or systemic illness. Ophthalmic examination revealed conjunctival hyperemia, epithelial irregularities, and a developing ring-shaped stromal infiltrate. In vivo confocal microscopy demonstrated double-walled hyperreflective cysts, and culture followed by PCR and sequencing confirmed the presence of Acanthamoeba T4 genotype. Despite intensive treatment with topical polyhexamethylene biguanide, chlorhexidine, propamidine, and voriconazole, as well as oral miltefosine, the infection progressed, leading to stromal necrosis. The patient underwent two therapeutic penetrating keratoplasties; however, the disease continued to advance, eventually resulting in phthisis bulbi and permanent vision loss. This case highlights the potential for aggressive, clinically refractory Acanthamoeba keratitis caused by the T4 genotype, emphasizing the importance of early diagnosis, vigilant monitoring, and timely surgical intervention in resistant cases.

Parasitic diseases are among the most widespread infections worldwide, causing millions of deaths and illnesses each year. So rapid and accurate diagnosis is essential, requiring highly sensitive and specific tests. Biosensors can provide significant advantages over traditional diagnostic methods because of their specificity, sensitivity, speed, simplicity, ease of use, repeatability, and capacity for early-stage disease detection. Recent advances in modern diagnostic tools for detecting parasitic infections use nanomaterials such as gold nanoparticles, carbon nanofibers, and carbon nanotubes. These developments have significantly lowered detection limits to the picogram and femtogram levels. This review will cover recent advancements in biosensor-based diagnostic techniques in parasitology.

Kiwi (Apteryx spp.) chicks in conservation captive-rearing programmes commonly suffer from coccidiosis, a parasitic disease that can cause significant morbidity and mortality in young birds. Current management combines preventative husbandry with treatment using coccidiocidal drugs. However, evidence suggests a lack of efficacy of toltrazuril, the primary drug used to treat coccidia, and limited information is available on safe and effective therapeutic alternatives for juvenile kiwi. This study evaluated the prophylactic efficacy of orally administered diclazuril (Coxiril 0.5% (5 g/kg) microGranulate premix, Huvepharma) for preventing coccidiosis in kiwi chicks naturally exposed to infection in captive-rearing facilities. Kiwi chicks (n = 6) received in-feed diclazuril at 0.5 mg/kg daily for 30 days, starting on the day of transfer to outdoor pens. An untreated control group (n = 6) was monitored in parallel. Health was monitored via clinical observation and blood biochemical analyses, while drug efficacy was measured using a combination of faecal oocyst counts, plasma concentration of diclazuril, and a molecular assay to assess changes in Eimeria spp. composition. In-feed diclazuril was well tolerated, with no adverse effects observed. Treated birds shed significantly fewer oocysts than control birds (p = 0.021). Changes in coccidia species composition suggested differential susceptibility of some kiwi Eimeria species to diclazuril. Further investigation of the optimal dose and treatment duration is recommended before integration of diclazuril into standard management protocols.

Advanced sequencing technologies require strict standards for DNA input and integrity. This study addresses the challenge of extracting high-quality, endogenous DNA from smaller arthropods with mixed DNA sources (arthropod, host, and microbiome), using Amblyomma triguttatum as a model organism. We evaluated three tissue types (Whole, Bisected, and Legs), three disruption methods (Undisrupted, Sliced, and liquid nitrogen bead Homogenisation), and two extraction kits (Qiagen DNeasy Blood & Tissue and MagAttract HMW) to optimise DNA yield, quality, and composition. The Qiagen MagAttract High Molecular Weight Kit significantly increased the proportion of large DNA fragments (20-48.5 kbp) by 11-fold compared to the Qiagen DNeasy Blood & Tissue Kit. Aggressive homogenisation methods produced the highest proportion of short fragments (97%, 1-10 kbp). Whole-Homogenised specimens yielded the highest DNA concentration (198 ng µL⁻¹), whereas Bisected-Undisrupted specimens achieved 146 ng µL⁻¹ with a greater proportion of large fragments (3.15%). Bacterial DNA content remained consistent across treatments. Our findings highlight the importance of selecting appropriate extraction methods to ensure optimal DNA quality for advanced sequencing applications. These results provide useful guidelines for optimising DNA extractions from smaller-bodied arthropods (~ 10-20 mg) and establish a framework for future studies to consider DNA quantity, quality, and composition.

Theileria and Babesia are emerging threats to wildlife health but remain underreported in captive large herbivores. This study aimed to investigate the presence and genetic identity of Theileria and Babesia in large captive herbivores in Thailand using PCR targeting the 18 S rRNA gene. Blood samples were collected from 31 individuals representing five herbivore species: Malayan tapirs (Tapirus indicus), white rhinoceroses (Ceratotherium simum), pygmy hippopotamuses (Choeropsis liberiensis), bantengs (Bos javanicus), and gaurs (Bos gaurus) across five zoological parks in central Thailand. A total of 16 positive samples were identified, including one coinfection, resulting in an overall infection rate of 51.6% (16/31; 95% CI: 33.1-69.9). Theileria equi-like was detected in 37.5% (3/8; 95% CI: 8.5-75.5) of Malayan tapirs. Theileria bicornis was detected in 75% (9/12; 95% CI: 42.8-94.5) of white rhinoceroses. In gaur, the infection rate was 33.3% (4/12; 95% CI: 9.9-65.1), comprising one Babesia ovata infection, two Theileria orientalis, and one coinfection. This study provided the first molecular confirmation of Babesia ovata infection in gaurs. No infections were detected in pygmy hippopotamuses or bantengs. These results provide novel baseline data on tick-borne pathogens in captive environments, highlighting potential risks to susceptible wildlife, both non-domestic and domestic species, and underscoring implications for conservation. Our findings emphasize the need for continued surveillance, integrated vector management, and targeted control strategies in zoological settings to mitigate pathogen transmission and protect animal health.