International Journal for Parasitology

The liver fluke, Fasciola hepatica, is a major parasitic threat to ruminant health and productivity worldwide, with important implications for food security, animal welfare, and zoonotic risk. This study developed and validated a multiplex deep amplicon sequencing assay targeting the mitochondrial NADH dehydrogenase 1 (mt-ND1) and cytochrome c oxidase subunit 1 (mt-COX1) loci for high-throughput genotyping of F. hepatica. DNA was extracted from eggs sedimented from sheep and cattle faeces (n = 78) received from farms and from adult worm pools (n = 12) isolated at abattoirs from diverse regions across the UK. Following high-throughput sequencing, bioinformatics analysis was performed to demultiplex Illumina sequence reads and extract amplicon sequence variants (ASVs). A total of 11 ASVs were identified at each locus (mt-ND1: 264-279 bp; mt-COX1: 312-319 bp), with two or three predominant ASVs per locus, along with rare variants. Network and PCA analyses revealed two distinct clusters at the mt-ND1 locus: one primarily associated with sheep and another shared between sheep and cattle. In contrast, mt-COX1 sequence reads formed a single dominant cluster. Population analyses revealed extensive ASV sharing across regions, indicating high gene flow, likely facilitated by livestock movement and parasite adaptation.

Background: Female genital schistosomiasis (FGS) is a neglected gynaecological manifestation of Schistosoma haematobium (S. haematobium) infection, resulting from the deposition of parasite eggs in the female genital tract. Although urogenital schistosomiasis is highly prevalent in parts of coastal Kenya, including Kilifi County, the burden of FGS among women of reproductive age remains poorly characterised. Routine diagnosis of S. haematobium infection relies largely on urine microscopy, which may underestimate genital involvement. This study aimed to assess the prevalence, diagnostic concordance, and risk factors for FGS among women of reproductive age in Kilifi County, Kenya. Methodology: In this cross-sectional study, 320 randomly selected women aged 15-50 years were recruited from rural Kilifi County; 261 provided complete data for analysis. A structured questionnaire was administered to collect sociodemographic and behavioural information. Urinary schistosomiasis was assessed using triplicate urine microscopy over three consecutive days, and FGS was evaluated using real-time polymerase chain reaction (PCR) targeting the S. haematobium Dra1 gene sequence on self-collected high vaginal swabs. Results: Overall, the prevalence of PCR-confirmed FGS was 36.0% (94/261), while urinary egg excretion was detected in 13.0% (34/261) of participants. Concordance between urine microscopy and genital PCR was 70.9%. Notably, 72% of women with PCR-confirmed FGS had no detectable parasite eggs in their urine. In bivariate analyses, factors such as urinary infection severity, water contact behaviours, haematuria, dysuria, age group, place of residence, and prior history of schistosomiasis were found to be associated with female genital schistosomiasis (FGS). However, in the multivariable logistic regression, only sub-location and urinary infection severity remained independently associated with the infection. Additionally, PCR cycle threshold (Ct) values showed a non-linear relationship with mean urinary egg counts, indicating that the detection of genital parasite DNA does not directly correspond to the urinary egg burden. Conclusion: FGS prevalence among women in Kilifi County was substantially higher than indicated by urine microscopy alone. The majority of women with genital schistosomiasis did not exhibit detectable urinary egg excretion, highlighting the limitations of routine parasitological screening for identifying genital disease. These findings underscore the need to incorporate genital sampling and molecular diagnostics into schistosomiasis control strategies targeting women of reproductive age in endemic settings.

Helminthiases remain a major global health burden, and limitations of current anthelmintic therapies highlight the need for new pharmacological targets. In this study, we examined the effects of ion-channel and cytoskeletal modulators on bovine lung protoscoleces (PSCs) of Echinococcus granulosus sensu lato. Compounds acting on ion channels (praziquantel, amiloride, and amlodipine) and cytoskeletal components (albendazole and cytochalasin D) were evaluated using a semi-automated motility assay, methylene blue exclusion to assess viability, and scanning electron microscopy (SEM) to characterize structural damage. All compounds produced concentration-dependent reductions in PSCs motility. Amlodipine was the most potent inhibitor of motility, whereas praziquantel and cytochalasin D produced pronounced tegumental alterations and strong correlations between motility impairment and parasite death. In contrast, amiloride markedly reduced motility with comparatively minor effects on viability, indicating a primarily paralytic effect. Cytoskeletal disruption induced severe structural damage and parallel declines in motility and viability. SEM analysis revealed extensive tegumental collapse, loss of glycocalyx, and microtrichial damage in PSCs exposed to cytoskeletal and calcium-modulating agents. These findings highlight cytoskeletal organization and calcium-dependent ion fluxes as key physiological vulnerabilities in E. granulosus. Comparative analysis of these pharmacological targets provides mechanistic insight into how disruptions in cytoskeletal dynamics and cation homeostasis compromise parasite motility and survival.

Haemosporida is a diverse order of vector-borne apicomplexan parasites infecting terrestrial vertebrates worldwide, including humans, but the evolutionary relationships among its genera remain unresolved. The phylogenetic placement of two bat-restricted genera, Nycteria and Polychromophilus, both of which lack erythrocytic schizogony, has varied across studies depending on taxon sampling and marker choice. To address this problem, an expanded dataset of near-complete mitochondrial (mtDNA) genomes together with nine nuclear loci were analyzed. Phylogenetic analyses of mtDNA recovered Nycteria and Polychromophilus as a strongly supported monophyletic clade. In contrast, analyses based only on the three mitochondrial coding genes (CDS) or a reduced nuclear dataset failed to recover their monophyly and showed low support and extensive topological conflict at deeper nodes. These results indicate that near-complete mitochondrial genomes recover phylogenetic signal that is not captured by reduced mitochondrial coding sequences or partial nuclear datasets. Molecular dating analyses further showed that divergence estimates for a putative Nycteria-Polychromophilus clade are compatible with the proposed times for bats diversification, and consistent with the broader haemosporidian timescale. When the Nycteria-Polychromophilus clade was incorporated as a calibration prior, divergence-time estimates became more precise without altering the overall evolutionary timeframe. Substantial mitochondrial gene-order rearrangements in a distinct Nycteria lineage were confirmed, highlighting structural divergence within this bat-associated group. In addition, heterogeneity in rates across mtDNA haemosporidian lineages was observed. Together, these findings support the existence of a distinct bat-associated clade whose deeper placement and evolutionary significance should be tested with broader phylogenomic sampling. Author SummaryMalaria parasites belong to a diverse group of organisms that infect many kinds of vertebrates, including birds, reptiles, and mammals (such as humans). Understanding how these parasites are related to each other is important for explaining how key biological traits have evolved. However, the relationships among major groups of haemosporidian parasites, including malaria parasites, remain unclear, particularly for those infecting bats. In this study, we focused on two groups of bat parasites, Nycteria and Polychromophilus, which share unusual biological features. The inferred evolutionary relationships of these two genera to other haemosporidians have been inconsistent across previous studies. By analyzing near-complete mitochondrial genomes, we found strong evidence that these two groups descended from a common evolutionary ancestor. In contrast, smaller datasets including nuclear genes failed to recover this relationship and produced conflicting results, suggesting that they lack sufficient information to resolve deep evolutionary relationships. We also found that this bat-associated lineage likely originated around the same time as early bats. In addition, we identified structural changes in the mitochondrial genome of one lineage, highlighting its evolutionary distinctiveness. Together, our results suggest that bats host a unique group of malaria parasites and demonstrate that more complete genetic data are essential for resolving their evolutionary history.

Background Urogenital schistosomiasis (UGS), caused by Schistosoma haematobium (S. haematobium), disproportionately affects women in sub-Saharan Africa and can lead to haematuria, anaemia, and urinary tract morbidity. Data on the prevalence in women of reproductive age remains limited in contrast to infection among school-aged children in Kenya. This study assessed the prevalence of UGS and its socioeconomic determinants among women in Kilifi County, Kenya. Methods: Urine samples (20-50 mL) were collected from each participant over three consecutive days. Day-one samples were tested for haematuria, proteinuria, nitrites, leukocytes, and pregnancy using dipsticks. On the other hand, 10 mL of urine was examined for S. haematobium eggs via urine filtration on all three days. Results: A total of 599 women aged 15-50 years were enrolled, with complete data available for 336. The mean age was 33 years; 57.7% were <35 years. Most participants were from rural Magarini Sub-county (63%) and engaged in crop farming (62.5%). Primary education was the highest level attained by 59.8% of participants. Frequent contact with stagnant water was reported by 92%. The overall prevalence of S. haematobium infection was 13.7% (95% CI: 10.2-17.8), higher in Magarini (14.9%) than in Rabai (12.0%), though not statistically significant. Younger age, primary education, and frequent water contact were associated with higher infection rates; however, after adjustment for covariates, haematuria showed the strongest independent association with infection. Women with haematuria were 25.2 times more likely to be infected (OR: 25.24, 95% CI: 7.07-82.63, p < 0.001); multivariate analysis confirmed haematuria as the sole significant predictor (OR: 20.83, 95% CI: 5.45-79.57, p < 0.001). Conclusion: UGS prevalence among women in Kilifi County is substantial, with variation between sub-counties. Haematuria demonstrated the strongest independent association with infection and may serve as a simple, non-invasive diagnostic marker. These findings underscore the pressing need for the integration of UGS screening into the reproductive health services and targeted interventions. Authors Summary UGS, caused by the parasitic worm Schistosoma haematobium, is a neglected tropical disease and remains a major public health problem in sub-Saharan Africa. Although control programmes in Kenya primarily target school-aged children, women of reproductive age are frequently exposed through daily water contact and may develop chronic urinary and reproductive health complications. However, data on the infection burden among adult women are limited. In this study, we assessed the prevalence of urogenital schistosomiasis and associated risk factors among women aged 15-50 years in Kilifi County, Kenya. Urine samples were collected over three consecutive days and examined for parasite eggs and indicators of urinary tract disease. We found that urogenital schistosomiasis affected more than one in ten women in the rural sub-counties where the study was conducted. Haematuria was strongly associated with infection and remained the most reliable predictor after accounting for other social and behavioural factors. These findings demonstrate that UGS is an under-recognised health issue among women and highlight the potential value of simple urine-based screening tools. Integrating UGS screening into existing reproductive health services could improve early detection and contribute to more inclusive disease control strategies.

Helminths are parasitic worms that secrete a variety of immune-regulating molecules to modulate the hosts inflammatory responses, enabling them to persist within the host over a long period of time, even decades. Their capacity to control host responses has prompted research into helminth-derived molecules as potential therapies for controlling excessive immune and inflammatory activity across a range of diseases. This systematic review with cross-study quantitative analysis aims to synthesize the published data on helminth-derived immunomodulatory peptides/polypeptides/proteins (HDIPs) with a focus on determining the extent of their disease-modifying and anti-inflammatory potential in in vivo animal models of inflammatory disease. In accordance with PRISMA 2020 guidelines, a predefined systematic search of the PubMed, Web of Science and Medline databases identified relevant studies published up to February 2026, and 65 articles were included after screening. We found that, although the HDIPs were assessed in multiple different disease models, most published studies assessed their potential in mouse models of colitis, asthma, arthritis and sepsis. Twenty species from which >65 isolated HDIPs were derived were tested in these models, with the trematode, Fasciola hepatica, and the nematode, Acanthocheilonema viteae, the most explored species. A common property of the HDIPs was the ability to significantly reduce disease severity across the in vivo animal models of inflammatory disease, underpinned by a decrease in pro-inflammatory cytokine levels and an increase in anti-inflammatory cytokine levels. Overall, this systematic review with cross-study quantitative analysis not only synthesizes the existing literature in this field but also highlights the disease-modifying and anti-inflammatory potential of HDIPs for a range of diseases in which immunoregulatory therapeutics may improve disease outcomes. It also encourages accelerated advancement of these helminth-derived molecules into first-in-human clinical trials.

Plasmodium vivax transmission from humans to mosquitoes depends on the density of gametocytes that in turn depends on asexual parasite replication and gametocyte commitment. These processes are often analyzed separately, despite being biologically linked and measured with substantial uncertainty. We used a joint Bayesian latent-variable model to simultaneously analyze parasite density, gametocyte density, and mosquito infectivity while accounting for measurement error and propagating uncertainty across linked processes. The model was applied to individual-level data from three P. vivax transmission studies conducted in Ethiopia (n = 455). A tenfold increase in gametocyte density was associated with more than a twofold increase in the odds of mosquito infection (odds ratio [OR] = 2.32, 95% credible interval [CrI]: 2.12-2.54). Asexual parasite density was also positively associated with infectivity after accounting for gametocyte density (OR = 1.74, 95% CrI: 1.60-1.90), and inclusion of parasite density improved predictive performance. Pathway decomposition within the joint model indicated that approximately 41% of the parasite-infectivity association operated through gametocyte density. Increasing age was associated with lower asexual parasite density but higher gametocyte density, resulting in minimal overall association with infectivity. Predicted infection probability increased sigmoidally with gametocyte density, remaining low at lower densities before increasing sharply and approaching a plateau at higher densities. Gametocyte density produced the largest predicted changes in the proportion of infected mosquitoes, while asexual parasite density added predictive information not fully captured by measured gametocyte density alone. This approach links molecular parasite measurements with mosquito infection risk while accounting for measurement uncertainty and provides an interpretable framework for studying the P. vivax infectious reservoir. Author SummaryMalaria transmission occurs when mosquitoes ingest sexual-stage parasites, called gametocytes, during a blood meal. In Plasmodium vivax infections, human-to-mosquito transmission depends on linked biological stages, including asexual parasite replication, gametocyte production, and mosquito infection. These processes are closely connected and often measured with uncertainty, making them difficult to study using standard approaches that analyze them separately. In this study, we applied a joint Bayesian model that analyzes parasite density, gametocyte density, and mosquito infectivity together while accounting for uncertainty in laboratory measurements. Using data from three studies in Ethiopia, we quantified how parasite density, gametocyte density, and host characteristics relate to mosquito infection. The analysis showed that measured gametocyte density alone did not fully explain variation in infectivity, and that asexual parasite density provided additional predictive information. We also found that age was associated differently with asexual parasite and gametocyte densities, resulting in little overall association with infectivity. This approach helps link molecular parasite measurements with transmission outcomes and improves understanding of the P. vivax infectious reservoir in endemic settings.

Human malaria infections begin with the injection of Plasmodium sporozoites via mosquito saliva. Whole sporozoite immunizations have been used as a model to study immune responses to malaria parasites, having culminated in circumsporozoite protein (CSP)-targeting vaccines and monoclonal antibodies (mAbs). However, antibody responses targeting non-CSP antigens on the sporozoite surface remain poorly characterized. Here, we isolated single B cells from a human volunteer immunized by Plasmodium falciparum-infected mosquito bites, who had acquired non-CSP-specific antibodies that recognize sporozoites. We identified two mAbs that recognize the surface of P. falciparum sporozoites, but do not bind to CSP. Using immunoprecipitation followed by mass-spectrometry, we found that the target of these mAbs is not a P. falciparum protein but the mosquito salivary protein SG1L3. We observed that recombinant SG1L3 binds to P. falciparum sporozoites. However, the SG1L3-specific mAbs and SG1L3-specific polyclonal antibodies from this volunteer, as well as polyclonal antibodies raised against recombinant SG1L3 in rabbits, fail to block liver stage infection in vitro, making this an unlikely target for functional antibodies. We observed that inhabitants from an area with intense Anopheles exposure in Burkina Faso can have antibodies against SG1L3, and that antibody titers increase with age. In conclusion, we identified the first human mAbs against a mosquito saliva protein that binds to the surface of sporozoites. Future work should assess whether naturally acquired antibodies against this protein may be used as a serological marker of mosquito exposure.

In Toxoplasma gondii, microneme proteins (MICs) are secreted components of the apical complex that play central roles in motility, host cell attachment, and invasion. Because proteins at the host-parasite interface are often predicted to evolve rapidly, MICs have been suggested as candidates for adaptive diversification. We tested this expectation using comparative analyses of three relatively understudied microneme proteins, MIC13, MIC12, and MIC16. Coding sequences were assembled from GenBank and ToxoDB, aligned by translation, and analyzed using maximum-likelihood phylogenetics, codon-based tests of selection, and predicted protein structure. MIC13 was represented by 51 sequences, MIC12 by 30, and MIC16 by 34, spanning multiple T. gondii haplogroups and including Hammondia hammondi and Neospora caninum as outgroups. All three genes were highly conserved among T. gondii strains, but their phylogenetic trees were topologically incongruent, indicating that individual MICs do not recover a single shared strain history. Contrary to expectation, no positively selected codons were detected in any gene. Instead, purifying selection was detected at one site in MIC13 and 15 sites in MIC12, while no significant codon-specific selection was detected in MIC16. Several constrained MIC12 sites overlapped annotated EGF and calcium-binding EGF-like domains, consistent with structural conservation of extracellular adhesion modules. AlphaFold prediction of MIC13 supported two sialic acid-binding micronemal adhesive repeat regions, but the single constrained MIC13 site did not overlap these motifs. Together, these results indicate that MIC13, MIC12, and MIC16 are shaped more by sequence conservation and heterogeneous gene histories than by strong recurrent positive selection. These findings refine expectations for microneme evolution in T. gondii and highlight conserved domains that may be important for parasite invasion and future functional study.

Parasitism is one of the key, structural, interspecific interactions in ecology. One remarkable parasitic strategy that has been documented in multiple systems is the behavioral manipulation of hosts to increase parasite fitness. While not yet documented in humans, we propose that a ubiquitous zoonotic parasite - Toxoplasma gondii - may change human behavior to favor the parasite by increasing the fitness of the parasites definitive host - cats. Specifically, we assess the possibility that human behavioral changes resulting from chronic, latent T. gondii infection lead to measurable changes in attitudes, actions and dopaminergic responses towards cats that function to increase domestic cat fitness. We assessed the potential role of humans in the T. gondii lifecycle by identifying and testing behavioral changes in humans that benefit the parasite; specifically, human affection for cats. We assessed T. gondii infection status in 68 participants using T. gondii serum antibody testing, and assessed their attitudes towards cats in three ways: i) surveys, ii) participant behavior in the presence of domestic cats, and iii) participant oxytocin levels before and after interactions with cats to assess dopaminergic changes. Only 2 of 68 participants were positive for T. gondii antibodies, limiting statistical power. However, our results indicated that T. gondii-positive participants both reported a greater affection for cats in surveys, and spent more time engaged with cats during behavioral trials than T. gondii-negative participants (87% of study time engaging with cats vs 75%). Oxytocin results were inconclusive.

Plant parasitic nematodes (PPNs) are microscopic soil dwelling pests that infect crops, using a lance-like organ, the stylet, to hatch, invade plant roots, and establish feeding sites. Stylet function is underpinned by pharyngeal muscle contraction and relaxation cycles, making it an attractive route to disrupt the PPN lifecycle. However, knowledge of pharyngeal regulation in PPNs is relatively limited. In the free-living nematode Caenorhabditis elegans, the nicotinic receptor EAT-2 stimulates pharyngeal contraction to facilitate feeding. Here we hypothesize that EAT-2 orthologues may regulate a similar function in PPNs. A phylogenetic analysis reveals that EAT-2 and its orthologues in other nematode species cluster as a distinct group suggesting that EAT-2 is exclusive of other animal species. We identified eat-2 in the genome of the potato cyst nematode Globodera rostochiensis and used in situ hybridization to establish an anterior expression pattern consistent with a pharyngeal function. In vitro pharmacological assays directly compared the response of C. elegans pharynx and G. rostochiensis stylet to cholinergic compounds. Both pharyngeal and stylet activity were stimulated by acetylcholine and nicotine, and these responses were blocked by the nicotinic receptor antagonists, mecamylamine and tubocurarine. These data are consistent with a conserved cholinergic pathway mediated by EAT-2 regulating pharyngeal muscle function. It highlights EAT-2 as a potential determinant of stylet thrusting and a promising pharmacological target to selectively mitigate PPN infections.

BackgroundOnchocerciasis remains a public-health challenge in the Democratic Republic of the Congo (DRC). The Kakoi-Koda focus, Ituri Province, exhibited high endemicity in the early 2000s and received community-directed treatment with ivermectin (CDTI) in some health zones (e.g., Nyarambe), but not in others (e.g., Logo). Moxidectin clinical trials were conducted in these health zones, alongside onchocerciasis-associated epilepsy studies. MethodologyWe synthesised epidemiological (including nodule prevalence), entomological and CDTI programmatic data. We collated anti-Ov16 serological data from epilepsy-related studies (community, cohort, case-control designs, 2015-2021) and skin-snip microscopy results from two moxidectin trial screenings (2009-2011; 2021-2023) and epilepsy-related studies (2015-2017). Geospatial analyses were used to describe land-cover change relevant to vector ecology and to identify areas with recent transmission. Principal findingsOnchocerca volvulus transmission declined markedly over time. In CDTI-naive Logo villages, microfilarial prevalence fell from 69-79% (first trial, 2009-2011) to 9% (second trial, 2021-2023), and mean infection intensity from 17-26 to 1 microfilariae per skin snip, similar to declines observed in Nyarambe villages under CDTI (72% to 3% and 11 to 0.4, respectively). Anti-Ov16 seroprevalence among children aged 3-10 years was low (0-5%) from 2016 onwards, and seropositivity was geographically circumscribed, mirroring contemporary skin-snip results. Human landing catches and breeding-site prospections (2015-2017) identified Simulium dentulosum and S. vorax as the current anthropophagic species, with no evidence of S. neavei after 2009. Progressive deforestation and canopy opening provide a plausible mechanism for a shift from crab-associated S. neavei habitats towards more open-habitat vectors. SignificanceConsistent parasitological, serological, entomological and geospatial evidence indicates substantially reduced transmission across Kakoi-Koda, with spatially-circumscribed residual transmission. Whether the current simuliid species can sustain transmission above elimination thresholds remains uncertain. Targeted, integrated surveillance is warranted to guide CDTI and stop-CDTI decisions. The dataset assembled here can be used to inform transmission modelling of these dynamics. Author SummaryOnchocerciasis, also known as river blindness, is a parasitic disease of public health concern in sub-Saharan Africa, transmitted by blackfly vectors. The disease is responsible for skin and eye clinical manifestations and is associated with neurological complications. We investigated an area in north-eastern Democratic Republic of the Congo called the Kakoi-Koda onchocerciasis focus, where the infection was once common. We reviewed and assembled data from past studies on infection in humans and blackflies, and analysed satellite imagery to assess the loss of tree cover that can affect where blackflies live and breed. We found that the prevalence of onchocerciasis in Kakoi-Koda has declined markedly in recent years. This decline appears linked to the disappearance (by deforestation) of the habitat suitable for some blackfly species, and to ivermectin distribution to treat onchocerciasis in parts of the focus. Our findings help to understand why onchocerciasis has decreased across the Kakoi-Koda focus and highlight a small number of fast-flowing river segments where other blackfly species may allow small pockets of local transmission. These results support continued, targeted monitoring to determine whether the disease is still transmitted in specific locations where elimination interventions may be needed.

Schistosomiasis is a neglected tropical disease caused by parasitic flatworms of the genus Schistosoma, impacting hundreds of millions of people and animals globally. Disease pathology primarily originates from host immune responses to parasite eggs, which are produced only when female schistosomes are continuously paired with males. Past research focused on pairing-dependent female sexual maturation, while scarce data exist for the males reproductive biology. In this study, we characterized the G protein-coupled receptor Smgpcr9 (Smp_244240), an orphan Class A (Rhodopsin-like) GPCR with a testis-preferential and pairing-influenced expression profile in S. mansoni males. Previous bulk RNA-seq analyses of adult worms and their isolated gonads revealed that Smgpcr9 belongs to a subgroup of GPCR genes with abundant testis-preferential and pairing-influenced transcript levels in males but low and extremely low expression in unpaired and paired females, respectively. This male-/unpaired female-biased expression pattern mirrors that of neuropeptide (npp) genes of S. mansoni such as Smnpp26 and Smnpp41. In a deorphanization approach using yeast-two-hybrid analyses, GPCR internalization experiments, bioluminescence resonance energy transfer assays, and by modeling and docking analyses, we provide first evidence that both NPPs can interact with SmGPCR9. Furthermore, we optimized a GPCR RNAi approach and achieved efficient transcript knockdown (> 90%) enabling robust functional characterization of Smgpcr9. Following RNAi, physiological and morphological analyses revealed that SmGPCR9 regulates key aspects of male reproductive biology like testis morphology and spermatogenesis. Remarkably, ovary structure and egg production were also affected in paired females post RNAi. We observed similar phenotypes plus motility constraints and reduced stem-cell proliferation in both sexes upon RNAi of Smnpp26 and Smnpp41. In all cases, RNAi downstream analyses by RT-qPCR of marker genes substantiated the observed phenotypic effects. These results strongly indicate the importance of SmGPCR9, SmNPP26, and SmNPP41 for spermatogenesis and further physiological processes in male and female S. mansoni. Author SummaryResearch of the reproductive biology of schistosomes focused mainly on females so far, which upon pairing sexually mature to produce eggs that are important for the life cycle maintenance but also for the pathogenesis of schistosomiasis, the infectious disease caused by these parasites. We investigated a yet unknown G protein-coupled receptor, Smgpcr9, which showed a testis-preferential and pairing-influenced expression profile in Schistosoma mansoni males. To this end, we optimized an RNA interference (RNAi) approach for knockdown analysis, identified neuropeptides (NPPs) as potential ligands by different biochemical approaches and modeling and docking analyses, and we investigated the roles of SmGPCR9 and two interacting NPPs, SmNPP26 and SmNPP41, by physiological, microscopical, and molecular techniques. Our results strongly suggest that SmGPCR9 and both NPPs regulate spermatogenesis. Furthermore, we detected effects on ovary morphology, egg production, and stem-cell proliferation of paired females post RNAi. Taken together, we deorphanized SmGPCR9 and showed for the first time the essential role of a so far uncharacterized GPCR and two interacting neuropeptides for spermatogenesis. Our results shed first light on spermatogenesis regulatory processes controlled by GPCRs and neuropeptides in male S. mansoni and thus expand our understanding of the roles of GPCR-NPP signaling for schistosome reproductive biology.

Purpose: Alpha-gal syndrome (AGS) is an emerging health issue. This syndrome, caused by the bites of ticks, induces allergic reactions to the sugar molecule galactose-alpha-1,3-galactose after exposure to non-primate mammalian meat and other byproducts. Agricultural workers spend significant time outdoors placing them at an increased risk for tick bites and tick-borne diseases, like AGS. This study aimed to characterize farmers and ranchers' prior knowledge, symptomology, and diagnostic experiences with AGS. Methods: We conducted a cross-sectional survey of more than 200 farmers and ranchers with a self-reported AGS diagnosis. The survey captured farmers and ranchers' experiences related to prior knowledge and experience with tick bites and AGS, reported symptoms, and obtaining a diagnosis. Findings: A total of 201 respondents across 26 states participated in the survey, with the majority from Missouri and Oklahoma. We identified four distinct symptom clusters, with the most reported symptoms being abdominal cramping, diarrhea, itchy skin, and nausea. Women more often reported gastrointestinal discomfort, and men were more likely to be in the mild symptom category. On average, participants reported 2.98 medical provider visits before receiving a diagnosis, most being diagnosed by general practitioners and allergists. Conclusions: No previous studies have focused on the symptom and diagnostic experiences of farmers and ranchers with AGS. Capturing such data is essential as these workers may experience unique occupational challenges following AGS diagnosis. The diagnostic experience data support a continuing need to educate and empower AGS patients and providers, especially agricultural workers and providers serving rural communities.

Belowground, plants are exposed to a wide range of biotic stresses that vary in severity and nature, including tissue damage, disruption of vascular connectivity, and depletion of assimilates. How plants adapt their root systems to cope with different types of belowground biotic stresses is not well known. In this paper we compare above- and belowground plant adaptations to three nematode species with distinct tissue migration and feeding behaviours to study mechanisms underlying tolerance to different types of biotic stresses. We monitored both green canopy growth and changes in root system architecture of Arabidopsis inoculated with Pratylenchus penetrans, Heterodera schachtii, and Meloidogyne incognita. This revealed three distinct phases in aboveground plant responses: (i) initial growth inhibition associated with host invasion and tissue damage, (ii) persistent growth reduction associated with nematode sedentarism, and (iii) late growth stimulus in more advanced stages of infection. Specific adaptations in the root systems further revealed fundamentally different stress coping strategies. Tissue damage and intermittent feeding by P. penetrans in the root cortex did not induce significant changes in root system architecture. Tissue damage to the root cortex and prolonged feeding on host vascular cells by H. schachtii induced secondary root formation compensating for primary root growth inhibition. Prolonged feeding on host vascular cell by M. incognita alone did not induce secondary root formation, but was accompanied by typical local tissue swelling instead. Our data suggest that local secondary root formation and tissue swelling are two distinct compensatory mechanisms underlying tolerance to sedentarism by root-feeding nematodes. HighlightHow plants utilize root system plasticity to cope with different types of biotic stresses by root feeding nematodes remains largely unknown. Here, we report on specific adaptive growth responses in Arabidopsis roots to three nematode species, Pratylenchus penetrans, Heterodera schachtii, and Meloidogyne incognita, with fundamentally different strategies for host invasion, subsequent migration through host tissue, and feeding on host cells.

The intermittent preventive treatment with sulfadoxine-pyrimethamine (IPTp-SP) remains the main strategy to prevent malaria in pregnancy. However, continued drug pressure may also contribute to the emergence of resistant parasites and impact the gametocyte carriage and subsequent infectiousness. Pregnant women are thought to be a potential reservoir for malaria transmission due to the increased carriage of gametocytes following long-lasting infections. We used molecular methods to examine 100 Plasmodium falciparum (P. falciparum) isolates collected from Mozambican women at delivery in 2014-15, to determine SP resistance polymorphisms in P. falciparum dihydrofolate reductase (pfdhfr) and dihydropteroate synthetase (pfdhps) genes as well as the presence of gametocytes by RT-qPCR. Overall, 54% and 7% of parasites harbored quintuple and sextuple pfdhfr/pfdhps mutant haplotypes, respectively. Gametocytes were detected in 34% of isolates. Gametocyte carriage was significantly associated with quintuple mutant infections (AOR = 7.5, p = 0.001), which accounted for 80% of infections with detectable gametocytes. Results indicate the relevance of ongoing surveillance of SP resistance in Mozambique to guide future evaluation of alternative IPTp approaches as resistance levels evolve and to anticipate potential implications for parasite transmission and maternal-fetal health.

Malaria remains a major global health burden, with traditional control methods facing challenges such as insecticide resistance and high operational costs. Genetic biocontrol offers a promising alternative for mosquito population suppression, but its field efficacy would require assessment. This study evaluates the role that population genomic statistics can play in detecting decreases in population size in the context of a cluster randomized control trial (cRCT), investigating the response of nucleotide diversity ({pi}), Tajimas D, segregating sites, and linkage disequilibrium (LD) under both constant and seasonal demographic scenarios. We simulated 90% and 99% population declines with various degrees of between-cluster heterogeneity, and assessed the detection power of each statistic over time and number of clusters per arm. Results show that Tajimas D is highly sensitive and robust across crash severity, seasonality and heterogeneity scenarios. Segregating sites has similar power to Tajimas D when baseline data are available. We further estimated that cRCTs require approximately 3 to 5 villages per treatment arm to achieve adequate statistical power. These findings provide recommendations for genetic monitoring of vector control interventions in wild populations.

Leishmaniases remain a significant global public health threat, with Leishmania amazonensis and Leishmania infantum representing the etiological agents of the cutaneous and visceral forms in the Americas, respectively. Building on our previous identification of Phospholipase A1 (PLA1) in Leishmania braziliensis, this study provides a comprehensive molecular, immunological, and biochemical characterization of PLA1 in L. amazonensis and L. infantum promastigotes. We analyzed PLA1 activity and expression, purified the recombinant enzyme from L. amazonensis, and validated protein expression using a specific anti-PLA1 serum. The major contribution of this research is the first description of the subcellular localization of a PLA1 within the Leishmania genus. Moreover, our results reveal an unprecedented association between PLA1 and lipid droplets within the parasites. This discovery is of particular interest as it provides the first evidence linking this enzyme to lipid storage organelles in Leishmania. Given that PLA1 is an established virulence factor in other trypanosomatids, these findings suggest a specialized role for the enzyme in parasite lipid metabolism and potentially in its pathogenic mechanisms, opening new perspectives for understanding Leishmania biology.

Rwanda is a malaria endemic country and a focal point for emerging Plasmodium falciparum artemisinin partial resistance (ART-R). While Demographic and Health Surveys (DHS) provide both national and province-level representative data, malaria testing in Rwandan DHS (RDHS) studies has been limited to a subset of adult women and children under 5 years using RDT and/or microscopy. Recent work using ultra-sensitive quantitative real time PCR on residual dried blood spots (DBS) from the 2014-15 RDHS revealed a significantly higher P. falciparum prevalence than detected by standard DHS diagnostics. Building on this study, we analyzed 7,127 adult DBS samples collected for HIV testing in the 2019-20 RDHS to generate updated prevalence measures. We found a national P. falciparum infection prevalence of 7.7% (95%CI [6.8%, 8.7%]), with predominantly low-density infections (median parasitemia: 7.3 parasites/uL). We assessed covariates of P. falciparum malaria infection, identifying male sex, lower household wealth, lower educational achievement, and residence at lower elevation as significant predictors. Notably, national P. falciparum prevalence decreased 53% relative to the parallel 2014-15 RDHS study, despite reports of increasing ART-R-associated mutations in Rwanda. These findings demonstrate the utility of ultra-sensitive molecular surveillance, and suggest that national malaria control efforts have substantially reduced malaria burden in Rwanda even amid rising antimalarial parasite prevalence. Subsequent studies on this data set will provide measures of minor Plasmodium species prevalence, as well as temporospatial analysis of antimalarial resistance markers in P. falciparum positive samples.

Background/aims The World Health Organization (WHO) aims to eliminate schistosomiasis as a public health problem (EPHP) across 78 endemic countries by 2030. However, for low-prevalence settings that reach EPHP, guidance on managing transmission to maintain EPHP or move towards Interruption of Transmission (IoT) is limited, partly due to insufficient evidence on drivers of resurgence. In Uganda, some communities inland from Lake Victoria have achieved EPHP for Schistosoma mansoni but not progressed to IoT. This study explored whether routine, short-range travel to the highly endemic lake could sustain transmission in these settings. Methods We conducted a cross-sectional study in five Ugandan villages ~5 km from Lake Victoria. Parasitological data were collected using Kato-Katz and Point-of-Care Circulating Cathodic Antigen tests, alongside questionnaires on lake travel from 585 individuals aged 1-91 years. A structural causal model estimated the total and direct effects of travel frequency, activity type, water contact duration, and drug treatment history on infection. Bayesian regression models and counterfactual simulations predicted infection under hypothetical interventions. Results Reaching IoT in low-risk villages may be undermined by habitual, short-range travel to high-risk sites, driven by the nature and duration of lake contact. Daily lake travel caused a 1.7-fold increase in odds of infection, while occupational activities caused a 3.4-fold increase compared with no lake activity. Counterfactual analysis showed that removing lake contact duration most reduced infection risk among moderate-frequency travellers, while daily travellers showed smaller changes, and some transmission persisted among individuals with little or no lake contact. Simulations demonstrated that modifying lake contact behaviours could reduce individual infection risk but had limited population-level impact. Conclusion These findings indicate that targeting only high-risk villages or individual behaviours is unlikely to achieve sustained, wide-spread IoT, underscoring the need for integrated control strategies that account for mobility, behaviour, and local transmission ecology.