Parasitology最新文献

The prevalence of female genital schistosomiasis (FGS) and male genital schistosomiasis (MGS) remains high in many low-to-medium-income countries, and each has sex-specific disease sequelae with wider detrimental gender and health impacts. Social science research studies on the former outnumber those on the latter. Indeed, in many countries across sub-Saharan Africa (SSA), MGS (as with male reproductive and sexual health issues in general) is overlooked, underappreciated, and broadly orphaned within urogenital and intestinal schistosomiasis research and control. Similarly, in those countries where MGS has been reported formally, its psychosocial dimensions and effects remain poorly understood, especially in terms of context-specific cultural and societal factors. In this scoping review, we attempt to better contextualize MGS within men's sexual and reproductive health and rights (SRHR) and general wellbeing, as it often draws parallels with social science research in FGS. We discuss common psychosocial determinants, highlighting why current surveillance of MGS is particularly poor and the primary health care response to mitigate it is bottlenecked and largely stalled within the wider health system, from both top-down and bottom-up perspectives. Our specific approach remains cognisant of the context of infected households where all members could be suffering from urogenital and/or intestinal schistosomiasis. Looking ahead, we develop and frame a pragmatic social science research agenda to encourage and better explore and assess the detrimental impact of MGS on infected men and boys, considering appropriate ameliorations more holistically within primary care.

Parasite transmission can be disrupted when their free-living larval stages are consumed by non-host organisms. Yet, the contribution of benthic scrapers to this process remains insufficiently explored. Here, we experimentally assessed the ability of the North American pulmonate snail Physa acuta to reduce the abundance of free-living digenean larvae - cercariae of Diplostomum sp. and Trichobilharzia sp., and adolescariae of Notocotylus sp. - and evaluated how this effect is modulated by snail body size and colonisation by other organisms. Larval consumption by P. acuta occurred in all treatments and was highest for settled Notocotylus sp. adolescariae, particularly among larger individuals. The extent of larval reduction varied with infection by digenean metacercariae (xiphidiometacercariae), which either enhanced or inhibited feeding depending on parasite identity. It also varied with colonisation by Chaetogaster limnaei limnaei, whose presence increased the ingestion of planktonic cercariae, likely due to the combined feeding activity of the snail and its commensal oligochaete. Most snails harboured metacercariae, indicating that P. acuta frequently functions as a second intermediate host in its non-native range. Our findings highlight the dual ecological role of P. acuta - both as a consumer of free-living parasite stages and as a competent host. This trophic interaction may disrupt parasite transmission while providing nutritional benefits that support the ecological success and spread of this non-native species. Conversely, by serving as a host, P. acuta may facilitate the persistence and dissemination of parasitic taxa in invaded ecosystems.

Besnoitia besnoiti is an apicomplexan parasite, the causal agent of bovine besnoitiosis. This disease is characterised by cyst formation in the skin and mucosa. During early infection, fast proliferating tachyzoites invade and replicate within host endothelial cells. In non-excitable cells, extracellular signals activate the inositol-triphosphate/calcium (InsP3/Ca²⁺) pathway, which depends on phospholipase C (PLC) activation, inducing an increase in IP₃ levels, followed by intracellular Ca²⁺ release. Despite the understanding of Ca²⁺ signalling, this process in B. besnoiti tachyzoites is unclear. This work aimed to study Ca²⁺ dynamics during B. besnoiti infection in bovine umbilical vein endothelial cells (BUVEC) and the role of the InsP₃/Ca²⁺ pathway during B. besnoiti infection. Ca²⁺ dynamics during tachyzoite replication were determined in B. besnoiti-infected BUVEC loaded with fluo-4-AM. The role of InsP₃/Ca²⁺ signalling for parasite invasion was evaluated by treatments with Ca²⁺ chelators (BAPTA, EGTA) or PLC inhibitors (U73122, D609). PLC activation was studied in fluo-4-loaded free tachyzoites using the PLC activator m-3M3FBS, in the presence or absence of PLC inhibitors. Current data show an infection-driven increase in total Ca²⁺ signals in B. besnoiti-infected BUVEC over time. BAPTA, but not EGTA, treatments of tachyzoites affected their invasion, reducing infection rates by 85.4 ± 9.3%, suggesting that intracellular Ca²⁺ sources are necessary for B. besnoiti invasion. In line, treatments with U73122 and D609 reduced infection rates by 79.3 ± 9.4% and 49.7 ± 8.9%, respectively, demonstrating that PLC participation is required for host cell infection. Finally, m-3M3FBS treatments induced a PLC-independent Ca²⁺ flux in B. besnoiti tachyzoites.

Schistosomiasis remains a significant public health concern in sub-Saharan Africa, particularly among women and children. In Cameroon, urogenital and intestinal schistosomiasis affect the lives of millions of impoverished populations, and female genital schistosomiasis (FGS) remains a serious threat which has not been quantified explicitly. The extent of stigmatization and discrimination related to FGS is currently unknown. This study explores the use of precision mapping to identify high-risk communities for urogenital schistosomiasis and guide targeted screening for FGS. Parasitological surveys were conducted between November 2020 and July 2021 in four health districts using urine filtration and Kato-Katz techniques, first in schools to identify areas of higher transmission, and secondly in selected high-risk communities. Geographic information system tools were employed to identify high transmission foci and households of targeted infected women. Results of surveys in schools showed no schistosomiasis transmission in Ayos (0%) and low prevalence in Akonolinga (8%), while Bertoua and Doume had high prevalence, up to 33% and 48% infection with Schistosoma haematobium, respectively. These results made the two health districts of Bertoua and Doume suitable for focused FGS investigations. Surveys in communities revealed higher schistosomiasis prevalence and infection intensity in Doume compared to Bertoua. Precision mapping effectively identified infected women and enabled targeted recruitment for further clinical studies, facilitating efficient resource allocation for gynaecological follow-up. This approach demonstrates the value of geospatial tools in enhancing targeted public health interventions, disease surveillance and control strategies.

The nematode genus Rhabdias comprises over 100 species of parasitic nematodes that infect amphibians and reptiles, with a wide geographical distribution. To date, 25 species have been reported from the Neotropical region. Despite this diversity, few integrative studies, combining morphological and molecular data have been conducted to characterize species within the genus. Therefore, the main objective of the present study is to describe, through an integrative approach, a new species of Rhabdias found parasitizing the lungs of an anuran with a high concentration of skin toxins, Dendrobates tinctorius, from the Brazilian Amazon. The new species of Rhabdias is characterized by an elongated body, uniform cuticular inflation attenuated at the extremities, 4 submedian lips and 2 lateral lips, a cup-shaped buccal capsule, and an elongated tail. The morphology of the buccal capsule in Rhabdias camposi n. sp. is also unique among Rhabdias representatives, as this morphological character is known so far. Thus, we emphasize that a detailed study of this morphological trait for species of the genus will be crucial for species diagnosis. Molecular and phylogenetic analyses were performed using mitochondrial COI gene sequences. We observed that the new taxon is closely related to Rhabdias waiapi, a parasite of Pristimantis chiastonotus. Rhabdias camposi n. sp. represents the 26th species of the genus reported from the Neotropics in amphibians and the first described from a Dendrobates tinctorius host in Brazil.

Liberia (West Africa) has an extensive (co)burden of urogenital and intestinal schistosomiasis; each largely restricted to more inland areas. Where urogenital schistosomiasis is endemic, as both disease surveillance and case management are nascent, many women may unknowingly be living with Female Genital Schistosomiasis (FGS). Using a recently developed FGS score card, we appraised FGS score card valuations with point-of-care gynaecological and molecular parasitological evaluations as undertaken within typical primary care settings of four Liberian counties. A total of 400 women, 100 participants from each of four endemic inland counties, underwent a cursory gynaecological examination using a speculum for visible FGS lesions, undertaken by a midwife, and provided a urine sample that was examined by centrifugation with microscopy for Schistosoma ova. Urine-sediments in ethanol were later analysed with a high-resolution melt (HRM) real-time (rt) PCR assay to screen for Schistosoma genetic markers. Using a combination of clinical and parasitological information, overall prevalence of UGS and FGS was <10% and a single case of putative FGS-associated co-infection with Schistosoma mansoni was observed. Participant interviews with the FGS score cards provided an insight into at-risk lifestyle and environmental factors, e.g. women who fished regularly were more likely to present with FGS whereas those who lived > 15 km from a local river were less likely to present with FGS. In this resource-poor setting of Liberia, active surveillance for FGS with either clinical or parasitological methods remains challenging such that sole future use of the FGS score card is most pragmatic for primary care.

Phlebotomine sand flies are found across multiple regions of Thailand, with growing recognition of their role in transmitting zoonotic pathogens. Environmental factors, including climate variability and vector ecology, may influence their distribution and activity, contributing to the potential spread of zoonotic pathogens in Southeast Asia. However, comprehensive data on sand fly distribution in Thailand remain limited. To address this gap, a systematic review was conducted following PRISMA guidelines. Out of 112 records retrieved, 33 met the inclusion criteria and quality assessment for further analysis. As per results, sand flies are widespread in Thailand, with a high level of species diversity comprising 42 species of 6 different genera. However, several provinces lack data on the presence and distribution of sand flies. Eleven species were identified as the overall abundant species throughout the studies from January 2007 to June 2025 and grouped by abundance: low-abundance species (Sergentomyia barguesae, Sergentomyia phadangensis, Sergentomyia barraudi and Sergentomyia indica), abundant but understudied species (Sergentomyia sylvatica, Sergentomyia anodontis and Neopulpus vietnamensis) and most abundant species (Sergentomyia hodgsoni, Sergentomyia gemmea, Sergentomyia iyengari and Sergentomyia khawi). From the most abundant species, S. khawi tested positive for several pathogens, such as Leishmania spp., Trypanosoma spp., Bartonella spp. and orbivirus. Besides, S. khawi has been shown to exhibit human-biting behaviour through the analysis of blood meal. These findings raise concerns about its potential role in pathogen transmission, especially concerning zoonotic pathogens. However, vector competence remains unproven for some of these pathogens, suggesting the need for further research.

The digenean trematode, Corrigia vitta, is a frequently reported component species in studies of helminth communities of wild rodents in Europe, especially those of wood mice and bank voles. It has been known since Dujardin first described the species in 1845, and yet its life cycle is still poorly defined, although Dicrocoeliidae typically have at least 3 hosts in their life cycles. Here, we review the history of nomenclature changes of the species, morphological studies, definitive mammalian host species range and evidence for the identity of intermediate hosts. We also review the epidemiology of C. vitta, searching for commonalities between studies that have assessed the effects of intrinsic and extrinsic variables on both prevalence and abundance of the species in wood mice. Furthermore, we identify gaps in knowledge and propose key objectives for future work on the species. We emphasize that if the life cycle of C. vitta could be established in the laboratory and maintained in laboratory mice, as a hepatopancreatic specialist in its definitive host, the parasite may turn out to be the source of novel medicines for the treatment of human pancreatic/liver diseases.

Recently introduced parasites are predicted to cause more severe infections because of a lack of host-parasite co-evolution. When new parasites co-occur with similar parasites they may compete for resources within a host, with mixed species infections potentially resulting in antagonistic, synergistic or additive effects. We tested Ostrea chilensis flat oysters in New Zealand for infections by two species of haplosporidian oyster parasites. Bonamia exitiosa is an endemic parasite to New Zealand, whereas Bonamia ostreae is an introduced species first detected in New Zealand in 2015. We investigated the infection intensity of each parasite by estimating gene copy numbers using species-specific digital droplet PCR (ddPCR) across Bonamia spp. allopatric and sympatric ranges. Our results showed that B. ostreae had significantly higher gene copy numbers than B. exitiosa. However, concurrent infections of both Bonamia parasites had similar intensities (based on gene copy number) to single-species infections, with no detectable interactive effects. Collectively, the results indicate that B. ostreae remains a significant risk to O. chilensis, although coinfections may not exacerbate disease. This study demonstrates the value of ddPCR screening and the importance of considering evolutionary ecology in the management of commercially important marine diseases.