Parasitology最新文献

Hippoboscoidea flies exhibit highly specific ectoparasitic relationships with bats, shaped by both intrinsic factors (e.g. bat behaviour) and extrinsic factors (e.g. land use). Understanding the dynamics of these parasite-host interactions is essential for uncovering co-evolutionary patterns and informing conservation strategies. To this end, we studied bat-fly interactions across different elevations in a montane forest of Amazonas, northern Peru. The most abundant bats were Carollia brevicauda, C. perspicillata and Sturnira oporaphilum, while Paraeuctenodes similis and Trichobius joblingi were the most common flies. Most flies exhibited monoxenous host specificity. Bat-fly interaction networks revealed high modularity and specialization at both local and regional scales. Modules typically grouped bat species of the same genus or subfamily, suggesting that phylogenetic constraints and roosting behaviour may shape those interaction patterns. Nestedness within modules (compound structure) emerged in the aggregated regional network, aligning with the integrative hypothesis of specialization. Although network structures were broadly similar across sites, species turnover contributed to subtle differences in module composition and specialization. These differences were congruent with the changes in species roles of certain bats and flies. This study represents the first of its kind in Peru and addresses significant knowledge gaps in the ecology of bat-fly interactions in the Neotropics.

Biomphalaria straminea (Gastropoda: Planorbidae) and Physa acuta (Gastropoda: Physidae), both invasive species in southern China, are important vectors for zoonotic diseases. However, the lack of information on the infection dynamics of Angiostrongylus cantonensis in these snails leaves gaps in understanding the compatibility mechanisms between the snails and the parasite. This study aims to reveal differences in A. cantonensis infection between B. straminea and P. acuta from Guangdong, southern China, and to investigate the potential interaction mechanisms between A. cantonensis and P. acuta. We found that both phenotypic color variants of B. straminea snails were highly susceptible to A. cantonensis (100%). The load of the L3 larvae ranged from 243 to 765 per snail, and it was positively correlated with the infection dosage. Based on the comparison of third-stage larvae quantities, B. straminea is more suitable than P. acuta for establishing the life cycle of A. cantonensis in the laboratory. In contrast, geographic isolates of P. acuta exhibited variable susceptibility (13-91%) and markedly lower parasite loads, with 6-32 third-stage larvae per snail. Diverse strains of P. acuta exhibit distinct immune responses to A. cantonensis, characterized by varied expression patterns of immune-related genes such as TEP1, HSP70, FREP2, Cu-Zn_SOD1, Fe-Mn_SOD2, MIF and Galectin. Our findings establish B. straminea as both a high-risk vector and a laboratory model for studying the life cycle of A. cantonensis, while highlighting P. acuta as a model for investigating parasite-snail interactions, thereby enhancing our understanding of snail-parasite dynamics in southern China.

Recently, the WHO published a Target Product Profile for a diagnostic test for cutaneous leishmaniasis (CL) and a Roadmap to 2030 for Neglected Tropical Diseases. The documents highlight that existing diagnostic tools for CL are insufficient, whilst setting clear goals for improved sensitivity and reduced cost. The need for species typing in diagnostics is also becoming more pressing with the emergence of drug-resistance, especially of Leishmania tropica. Serological tests are unable to do this, while techniques that can, like PCR, require complex and expensive machinery. Isothermal assays like LAMP offer a promising solution, but more work also remains, as few species-specific LAMP assays have been developed thus far and CL in Ethiopia is particularly neglected. Additionally, since the COVID-19 pandemic, many cheap isothermal diagnostic devices have been produced, which have yet to be tested in the diagnosis of CL. Finally, artificial intelligence presents another avenue for rapid diagnosis by image analysis. In this comprehensive review, we examine the opportunities and challenges inherent to diagnostic development for CL, a priority undertaking that still faces many developmental hurdles.

Both host identity and environmental factors are known to influence parasite species richness. Here, we analysed selected host traits and environmental variables associated with 3 aspects of helminth diversity in African ruminants. Based on the helminth faunas of 35 species of antelope and 1 species of giraffe, we studied drivers of species richness as well as taxonomic and functional diversity, combined for all helminths and separately for nematodes, cestodes and trematodes. A larger geographic host range and/or multiple habitats were associated with higher species richness in all helminths and each group individually as well as with functional diversity in all helminths, trematodes and cestodes. A wider host distribution range and larger relative brain size were both linked to higher taxonomic diversity in all helminths, and an increase in host longevity was linked to higher taxonomic diversity in nematodes. A higher level of climate moisture, relative humidity and primary production had a positive effect on trematode species richness and taxonomic diversity in all helminths, while trematode taxonomic diversity decreased in hosts from drier areas but increased in cestodes harboured by hosts from warmer areas. Our results highlight that patterns in parasite species richness and diversity emerge from an interplay of numerous factors, including host biology, environmental conditions and ecological traits of the parasites themselves. This points to the importance of carefully choosing the range of hosts considered for large-scale parasite diversity studies and underscores the need to avoid grouping too many types of parasites when looking for ecological patterns.

Parasites can strongly influence host populations, particularly when the host is an ecosystem engineer. Oysters are ecosystem engineers that support estuarine communities and fisheries but are susceptible to 2 protozoan parasites, Perkinsus marinus (causing Dermo) and Haplosporidium nelsoni (causing MSX). Although both parasites are known to be influenced by environmental conditions, fine-scale temporal and spatial patterns remain underexplored in southeastern US estuaries. We examined parasite prevalence and intensity biweekly from April to October 2023 across 4 intertidal reefs on Sapelo Island, Georgia, and analysed concurrent water quality data (temperature, salinity, dissolved oxygen, pH) to identify potential environmental drivers of parasite prevalence and intensity. Parasite prevalence was high overall, 88% of oysters were infected with at least 1 parasite, and 34% were co-infected. Haplosporidium nelsoni prevalence was consistently high across sites, while P. marinus prevalence showed greater spatiotemporal variability, increasing through late summer and fall. Models indicated a time-lagged effect of environmental conditions on P. marinus prevalence, specifically with temperature and dissolved oxygen. Prevalence of H. nelsoni remained high throughout the year among sites and was best explained by temperature variability, salinity, and dissolved oxygen. Intensity levels did not differ among sites for either parasite. Our results demonstrate that even at small spatial scales and over time, oyster-parasite dynamics are shaped by multiple, interacting environmental factors, with time-lagged responses particularly evident for P. marinus. Understanding these dynamics is essential for predicting disease impacts under changing environmental conditions and informing management, restoration, and aquaculture strategies.

Freshwater snails are important intermediate hosts for several parasitic diseases, including fascioliosis and schistosomiosis, with significant impacts on human and animal health. In Bangladesh, vector snails have been identified only by morphology. Here, we validate the species of freshwater snails acting as intermediate hosts for Fasciola and Schistosoma spp. using molecular and bioinformatics tools. Following morphology and morphometrics, we identified 9 species of snails: Lymnaea auricularia, Lymnaea luteola, Indoplanorbis exustus, Physa acuta, Viviparus bengalensis, Brotia spp., Thiara spp. and Pila globosa. Cercarial shedding tests revealed that L. auricularia (0.72%, 7 out of 977) and L. luteola (0.36%, 8 out of 2240) shed fasciolid cercariae, which polymerase chain reaction (PCR) confirmed. But I. exustus (5.43% 19 out of 350), L. auricularia (9.42%, 92 out of 977), L. luteola 10.09% (226 out of 2240), P. acuta (2.4%, 11 out of 450) and V. bengalensis (0.14%, 7 out of 500) shed schistosomatid cercariae. The same snail did not shed both fasciolid and schistosomatid cercariae simultaneously. PCR and sequencing of the Cox1 gene confirmed the species of the intermediate hosts. The sequences of L. auricularia, L. luteola, I. exustus, P. acuta and V. bengalensis were identical (99-99.7%) to reported sequences of these species. Phylogenetic analysis revealed that sequences of the present study for each species formed well-separated clusters with the corresponding reference sequences. Taken together, the results of this study highlight the importance of molecular tools for confirming snail species and will help target specific vector snails in the particular habitat when designing snail-borne trematode control programs.

Haemonchus contortus, a highly pathogenic gastrointestinal nematode, significantly impacts small ruminant production, causing substantial economic losses in sheep and goat farming. This study examined the genetic diversity and population structure of 171 H. contortus isolates collected from the abomasa of sheep slaughtered across 8 distinct regions in Xinjiang, China. Using sequence analysis, phylogenetic reconstruction and population genetic analyses of the mitochondrial nad4 gene, we identified 163 haplotypes, with haplotype diversity ranging from 0.995 to 1.000 and nucleotide diversity from 0.02007 to 0.03145. The Tacheng population displayed the highest nucleotide diversity. Analysis of molecular variance revealed that 91.83% of genetic variation occurred within populations, with minimal differentiation among them (Fst: -0.01296 to 0.04274). Neutrality tests (Tajima's D and Fu's Fs) indicated no recent population bottlenecks. Phylogenetic and haplotype network analyses showed no distinct geographic clustering, suggesting extensive gene flow, likely facilitated by host movement. These findings provide critical insights into the genetic structure of H. contortus in Xinjiang, informing strategies for managing anthelmintic resistance and controlling this economically significant parasite.

Theileria parva, a protozoan parasite, is the causative agent of East Coast fever (ECF), an economically important disease of cattle in sub-Saharan Africa. The Muguga cocktail vaccine which comprises 3 T. parva strains, namely Muguga, Kiambu 5 and Serengeti transformed, is used for immunization of cattle to control ECF. However, the relative contributions of these T. parva strains to vaccine efficacy are not fully understood. This study compared the in vitro infectivity of the strains at varying concentrations of 2.75, 84.5, and 169 infected acini/ml using peripheral blood mononuclear cells isolated from a bovine donor. The presence of Schizonts in cytospin smears was used to determine infectivity rates. The results indicated significant differences in the overall infectivity among the 3 strains at the concentrations 2.75 and 84.5 infected acini/mL but not at 169 infected acini/mL (p ≤ 0.05). These results suggest that infectivity potential reduces as the concentration increases. This was also supported by the observation that contamination increased at higher concentrations, complicating visualization and analysis. The findings reinforce the need to support the balanced composition of the Muguga cocktail vaccine to ensure broad-spectrum protection against ECF. This study emphasizes maintaining strain proportions in vaccine formulations. Future research should focus on advanced molecular techniques to refine infectivity assessments and explore strain-specific immune responses in vivo, contributing to optimized vaccine efficacy and sustainable control of ECF in endemic countries.

Through an integrative approach that combined microscopy and molecular analyses of the 18S rDNA gene, this study describes a novel haemococcidian species, Lankesterella nucleoflexa sp. nov., and presents data on another Lankesterella sp. Both parasites were found in the green iguana (Iguana iguana) from Eastern Amazonia, Brazil. Lankesterella nucleoflexa sp. nov. is characterized by a unique nuclear plasticity; its nucleus exhibits variable shapes and condensation states, appearing condensed and seemingly divided when adjacent to the host cell nucleus and elongated when positioned opposite. This species infects erythrocytes, monocytes and heterophils, inducing significant nuclear deformities. Phylogenetic analysis placed both Lankesterella sequences in a clade with other Lankesterella parasites from lizards, highlighting the genetic diversity of this genus within this host group. These findings expand the knowledge about parasitic biodiversity in Neotropical reptiles and underscore the necessity of integrating morphological and molecular methodologies to elucidate the taxonomy of understudied groups such as haemococcidians.

Rattus rattus is a known reservoir of zoonotic pathogens, including Bartonella and Rickettsia, transmitted by ectoparasites such as fleas, mites, lice and ticks. The circulation of Bartonella and Rickettsia in these vectors in Chile remains poorly characterized. To evaluate the association between ectoparasite abundance, prevalence and diversity (including lice, fleas, mites and ticks) and the presence of Bartonella and Rickettsia within ectoparasites collected from R. rattus across different anthropogenic gradients in Chile, a total of 1,339 ectoparasites were collected from 411 R. rattus individuals across 27 localities. Ectoparasites were identified morphologically, and molecular detection of bacteria was performed using conventional and qPCR, targeting multiple genetic markers. Haplotype diversity and phylogenetic relationships were assessed. Bartonella and Rickettsia DNA were detected in fleas, ticks, mites and lice of R. rattus, with prevalence values reported separately for pooled and individually analysed ectoparasites. Bartonella tribocorum, B. rochalimae and B. mastomydis were identified. Rickettsia felis was confirmed in multiple ectoparasite groups. High haplotype diversity was observed in Bartonella but not in Rickettsia. Urbanization and tick prevalence were negatively associated with Bartonella occurrence; flea and tick prevalences were negatively associated with Rickettsia. Rattus rattus and their ectoparasites harbour a diverse range of potentially zoonotic Bartonella and Rickettsia species. These findings highlight the need for integrated surveillance and vector control strategies, especially in areas with variable human-wildlife interaction.