Enolase 2 (ENO2) is a crucial an important glycolytic enzyme involved in glycolysis and is also recognised as a multifunctional protein. However, its interacting proteins in intestinal porcine epithelial cells (IPEC-J2 cells) remain unclear. This study investigates the interacting proteins of Cystoisospora suis (Biester et Murray, 1934) ENO2 (CsENO2) in IPEC-J2 cells. According to our previous research, CsENO2 is highly expressed in sporulated oocysts. Co-immunoprecipitation/liquid chromatography-mass spectrometry (Co-IP/LC-MS) was conducted using the pcDNA3.1-Flag vector carrying the enolase 2 gene, which was transfected into IPEC-J2 cells to co-immunoprecipitate with cellular proteins. The Co-IP/LC-MS-based protein sequencing identified three cellular proteins: NME2, RPS3, and Vimentin. Subsequently, cDNAs encoding the complete coding sequences of these proteins were cloned into the pGEX-4T-1 expression vector. Immunofluorescence assays revealed the localisation of CsENO2 in sporulated oocysts and sporozoites. Most CsENO2 protein was found in the cytoplasm of sporulated oocysts. In sporozoites, CsENO2 protein was primarily distributed around and outside the nucleus. This study aims to identify CsENO2-interacting proteins in IPEC-J2 cells and determine the localisation of CsENO2 within sporulated oocysts and sporozoites.
The species diversity of reptile parasites in the New World, including South America, remains poorly understood, and this also applies to tapeworms (Cestoda: Onchoproteocephalidea). Only 17 species of the non-monophyletic genus Ophiotaenia La Rue, 1911 have been recorded in reptiles in the Neotropical Region. In this paper, three new species are described from dipsadine snakes of the genus Erythrolamprus Boie (Colubridae) in Brazil and Paraguay, and a new genus, Penetrocestus, is proposed to accommodate these tapeworms that penetrate the intestinal wall of their hosts. The new genus differs from other proteocephalids parasitising snakes by the presence of a large apical glandular organ, which is larger than the suckers, and a large vaginal sphincter lined with a thick layer of chromophilic cells. Penetrocestus gen. n. is also characterised by a long and wide region ('metascolex') posterior to the scolex and a well-developed inner longitudinal musculature, which is weakly developed in most proteocephalids parasitising Neotropical snakes. Ophiotaenia joanae (de Chambrier et Paulino, 1997) from Xenodon neuwiedii Günther (Colubridae) in Brazil is transferred to Penetrocestus as its type species and as a new combination. Penetrocestus gorgonae sp. n. from Erythrolamprus aesculapii (Linnaeus) in Brazil, Penetrocestus jaegeri sp. n. from Erythrolamprus jaegeri (Günther) in Paraguay, and Penetrocestus tristani sp. n. from Erythrolamprus poecilogyrus (Wied-Neuwied) in Paraguay differ from Penetrocestus joanae (de Chambrier et Paulino, 1997) comb. n. and from each other by the position of the metascolex, width of the scolex, morphology of the terminal (distal) portion of the vagina, and the number of testes, as summarised in the key to their identification. The phylogenetic relationships of the new species are unknown, as they were collected more than 35 years ago and no tissues were fixed in ethanol for genetic characterisation, but the new data support the assumption of strict host specificity of reptilian tapeworms in the Neotropical Region.
The monogenean ectoparasite Gyrodactylus salaris Malmberg, 1957 was detected in 2001 on juveniles of landlocked Salmo salar Linnaeus in three rivers draining to Lake Kuitozero in the White Sea basin. The ancestry of the colony was studied by internal transcribed spacers of the nuclear ribosomal operon (ITS), mitochondrial COI gene and by 12 microsatellite markers. The maternal ancestor was a frozen heterozygotic and heteroplasmic diploid clone RBT marked by a ITS-1068R, spread by rainbow trout and observed in Denmark, Norway, Finland and Russia. The clone combined genomes from two divergent matrilines, probably from grayling (Thymallus Linck) in the Southern Baltic basin (COI alien, 84 % bootstrap support) and in Balkans (COI rbt, 99 %). The genetic distance of the 1545 bp sequences was dMCL = 0.025. The population in Kuitozero was a progeny of RBT females repeatedly inseminated by conspecific males. It was sexual but propagated as parthenogenetic clones. The derived population carried only COI rbt.. The microsatellite alleles of the RBT clone segregated with the paternal alleles following Mendelian model, with an excess of heterozygotes: He = 0.608, Ho = 0.883. Among 244 genotyped worms, 27 multilocus clones were observed, as segregated among the parr (FST = 0.824). Parental genotypes were not detected. The largest clone (104 worms) was heterozygotic in all 12 loci and was identified on fifteen fish, in two rivers and four years. The balancing selection (excess of heterozygotes) equalised the allelic frequencies and maximised the genetic variance available for purifying and adaptive natural selection on a new host. The two sexual episodes associated with three host switch steps offers a model to understand the evolution of the diverse host spectrum of host-specific Gyrodactylus von Nordmann, 1832.
The discovery of multiple metabolic enzymes encoded by genes of apparent plant or cyanobacterial origin in trypanosomatids led to the influential hypothesis that the common ancestor of Euglenozoa harboured a plastid that was subsequently lost in kinetoplastids. Here, we critically re-evaluate this hypothesis using an expanded, phylogenetically balanced dataset comprising 299 eukaryotic and 102 bacterial species. We reassess the evolutionary histories of 16 genes encoding proteins previously interpreted as evidence for an ancestral euglenozoan plastid using state-of-the-art maximum-likelihood and Bayesian phylogenetic approaches, supplemented by topology tests. Our analyses reveal that none of the examined genes provides compelling support for a plastid-bearing ancestor of Euglenozoa. Instead, these enzymes display heterogeneous evolutionary origins consistent with multiple independent horizontal gene transfer events between euglenozoans and diverse bacterial (distinct from cyanobacteria) and eukaryotic donors. Only the gene encoding a vacuolar H⁺-pyrophosphatase, an electrogenic proton pump, shows limited affinity to chloroplast-bearing lineages, and this signal alone is insufficient to infer plastid ancestry. Taken together, our results strongly suggest a horizontal gene transfer from various non-plastid bearing lineages over the hypothesis of plastid presence in the euglenozoan common ancestor with subsequent loss in kinetoplastids, diplonemids, and non-photosynthetic euglenids.
The temporal dynamics of parasite communities of the Three-spot cichlid Amphilophus trimaculatus Günther 1867 was examined during an annual cycle. A total of 770 fishes were collected between March 2019 and February 2020 from a tropical costal lagoon. Thirteen taxa of metazoan parasites were identified, two of monoxenous and 11 of heteroxenous parasites. No significant changes were observed in the species composition of parasite communities in A. trimaculatus during a 12-yr period (2008-2020). The prevalence of infection of six heteroxenous parasites Austrodiplostomum ostrowskiae Dronen, 2009, Cladocystis cf. trifolium Poche, 1926, Clinostomum cf. tataxumui Sereno-Uribe, Pinacho-Pinacho, García-Varela et Pérez-Ponce de León, 2013, Crassicutis cichlasomae Manter, 1936, Southwellina cf. hispida Witenberg, 1932 and Contracaecum sp. varied between sampling months, and/or climatic seasons. Some species were more prevalent during some months of the dry season, while others during the rainy season, suggesting that these parasite populations respond differently to environmental changes. The environmental changes generated by the dry/rainy cycle may have affected the availability of intermediate host populations, and the feeding and reproductive behaviour of the host. Temporal variations in the infection levels of some parasite species generated important changes in the structure of the component communities over time. This study allows us to appreciate the sensitivity of parasite-host systems to environmental variability, and suggests that alterations to hydrological regimes could have significant consequences on parasite biodiversity in tropical brackish water environments.
During a parasitological survey of the common cuttlefish Sepia officinalis (Linnaeus) collected from the Bizerte Lagoon in northern Tunisia, adult acanthocephalans were found attached to the internal wall of cuttlefish stomach. The presence of adult acanthocephalans in cephalopods is unusual, given that definitive hosts for these obligate endoparasites are typically vertebrates. A detailed morphological examination of both sexes using light and scanning electron microscopy revealed high morphological similarities to Acanthocephaloides irregularis Amin, Oğuz, Heckmann, Tepe et Kvach, 2011. A partial sequence of 604 bp of the cytochrome oxidase subunit I (COI) gene was successfully generated. Phylogenetic analysis based on COI gene confirmed the identification, showing that the Tunisian isolate of A. irregularis clustered closely to A. propinquus (Dujardin, 1845) from Gobius bucchichii Steindachner. This study presents the first record of A. irregularis in S. officinalis in the Mediterranean Sea, offering new insights into its life cycle, host specificity, and ecological significance within benthic food webs. This finding raises important questions about the role of cephalopod hosts in the transmission dynamics of acanthocephalans in marine environments.
A new nematode genus and species, Ophthalmonema diodontis gen. et sp. n. (Cystidicolidae), are established based on female specimens (males remain unknown) collected from both eyes of an aquarium-kept spot-fin porcupinefish, Diodon hystrix Linnaeus (Diodontidae, Tetraodontiformes), originally caught in coastal waters off Florida, USA. Examination by light (LM) and scanning electron microscopy (SEM) revealed that the mouth structure of this nematode, particularly the presence of two conspicuously large, rounded, opposing dorsoventral plates, each connected by a narrow bridge to the inner end of the pseudolabium, is unique among all cystidicolid genera. Inadequately described cystidicolid nematodes previously reported from the eye and surrounding tissues of D. hystrix and Diodon nicthemerus Cuvier in the Caribbean Sea and in waters off southern Australia, respectively, as Metabronema sp. or Cystidicolidae gen. sp. are considered to belong to the new species O. diodontis. A key to cystidicolid genera is provided.
The paper reports records of in situ spores of Paleozoic early land plants totalling 44 genera with 72 species (including four subspecies). Their reproductive organs yielded in situ spores belonging to 3 cryptospore species and 18 spore genera with 59 species. All descriptions of in situ spores have been modified employing current terminology for the description of Paleozoic spores. In situ spores of early plants are usually small, morphologically simple and can be divided into a few morphological groups. The most abundant spore genera are Apiculiretusispora, Retusotriletes and Ambitisporites.
The paper documented, branched hyphae preserved on the adaxial cuticle of pinnules of the Pennsylvanian leptosporangiate fern Discosoropteris chlupatum P & scaron;eni & ccaron;ka et al. from the Whetstone Horizon, Radnice Member, Kladno Formation of the Pilsen Basin, Czech Republic. The hyphae occur as running structures on the leaf surface, show simple septa and lack clamp connections, consistent with an ascomycete affinity. Exceptional host-tissue preservation indicates rapid burial by volcanic ash and supports epiphyllous colonisation, most plausibly parasitic, although early saprotrophic colonisation cannot be excluded. This record expands the limited evidence of Paleozoic foliar fungi preserved as compressions and highlights the potential of volcaniclastic deposits for detecting plant-fungus associations.
Research on the molecular genetics of Echinococcus has advanced significantly owing to its relevance in understanding genetic variation, host-parasite interactions, and the transmission of Echinococcus species. A bibliometric analysis was performed using RStudio (Bibliometrix) and VOSviewer to evaluate molecular genetic research on Echinococcus spp. published between 1985 and 2025. Data were extracted from Scopus, Web of Science, PubMed, Europe PMC, and ProQuest. The analysis revealed a steady rise in publications on Echinococcus molecular genetics, accelerating from the early 2000s and peaking around 2017, with a slight decline after 2023, reflecting fluctuations in research activity. Comparative analysis showed Echinococcus consistently surpassed Schistosoma, Taenia, and soil-transmitted helminths, peaking at 60 articles in 2020-2021. Early publications achieved high mean Total Citations (TC) per year, followed by a stable trend, indicating lasting impact. Leading journals included Parasitology Research (Germany; 70 articles, H-index 114), Veterinary Parasitology (Netherlands; 62, H-index 150), Parasitology (UK; 53, H-index 173), Acta Tropica (Netherlands; 34, H-index 122), and PLOS Neglected Tropical Diseases (USA; 28, H-index 172). Tehran University of Medical Sciences (54 articles) led institutions. Influential authors included D. P. McManus and T. Romig. Multinational studies (484 publications) had higher citations than single-country (474). Iran (121), China (116), and Italy (53) led global contributions, emphasising collaboration, genotyping, phylogeny, and veterinary applications. This bibliometric study underscores the evolving trends in Echinococcus molecular genetics, providing valuable insights for researchers and stakeholders to guide future investigations and collaborative strategies in controlling echinococcosis.
Background: Schizophrenia often features low-grade neuroinflammation. Because latent toxoplasmosis (LT) is common in this population, we tested whether LT yields a biomarker pattern resembling that reported in schizophrenia. Methods: We quantified 15 cytokines and 15 blood markers of brain injury in 65 LT-positive individuals and 103 matched LT-negative controls using multiplex immunoassays. Multivariate effects of infection, age, sex, and their interaction were assessed by MANCOVA and PERMANOVA. Effects on individual biomarkers were tested by partial Kendall correlation (controlling for age and sex). Differences in the internal correlation structure were evaluated with Mantel tests on dissimilarity matrices derived from partial correlations. Results: LT was associated with higher KLK6, S100B, and TDP-43 and lower MIF; several other markers showed nonsignificant but sizable trends. Cytokines showed reduced IFN-γ, IL-1β, and MCP-1 and elevated IL-13 and IL-17 in the infected group. Sex-stratified analyses suggested stronger effects on brain-injury markers in women and on cytokines in men. Correlation structure also diverged: infected individuals exhibited more negative links between brain-injury markers and cytokines, whereas controls showed predominantly positive associations (Mantel r = 0.461, p = 0.043). The LT profile overlapped with schizophrenia in elevated KLK6 and S100B and, in men, reduced GDNF, but contrasted for MIF and for the overall cytokine pattern (no consistent IL-6/TNF-α elevation). Conclusions: LT entails neuroinflammatory and neuroimmune alterations that only partly recapitulate schizophrenia; the biomarker pattern and interrelationships differ, arguing against LT as the main driver of schizophrenia-related neuroinflammation. Keywords: Chronic toxoplasmosis; Neuroimmune communication; HPA axis dysregulation; Inflammatory signaling; Glial activation markers; Brain injury biomarkers; Sex-specific immune modulation; aging. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement Czech Science Foundation supported this work (grant no. 22-20785S) ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: The study was approved by the Institutional Review Board of the Faculty of Science, Charles University (approval number 2021/4), and conducted in accordance with applicable regulations and ethical guidelines. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes All data produced are available online at figshare 10.6084/m9.figshare.30408286
With more than 62 reported species, Tunisia has a rich diversity of elasmobranchs. However, investigations of their parasites in Tunisian waters remain rare and fragmented. With the global biodiversity crisis that most living species are facing, the study of parasite diversity is crucial for assessing ecosystem health and host-parasite interactions. In this study, 2,092 specimens of cartilaginous fishes (Chondrichthyes: Elasmobranchii) belonging to eight species, six genera and five families were sampled along the Tunisian coast and examined for their ectoparasites. The different host species were each infected by at least one ectoparasite species. A total of 24 ectoparasite species, among which three new species, were collected and identified. Copepods exhibited the highest taxonomic diversity (11 species), followed by 'monogeneans' (6 species), isopods (5 species), and leeches (2 species). To understand the diversification and specialisation of the collected ectoparasite species and the factors that may influence them, parasitological indices, parasitic communities' composition, parasitic richness and seasonal variation are presented in this work. Parasite community structure varied among host species and families. Mustelus mustelus (Linnaeus) showed the greatest diversity (Shannon-Wiener H' = 1.91; Species richness (SR) = 10), whereas Torpedo torpedo (Linnaeus) hosted only a single leech species. The present study demonstrates that parasite community composition and structure of the studied hosts seem to be influenced primarily by the geographic distribution, the sampling effort and the population density, along with other factors such as the phylogeny of the host species.
The pathogenicity of haemogregarines and their effects on the health status of ectothermic hosts remain largely unexplored. In this study, we examined the impact of Hemolivia mauritanica (Sergent et Sergent, 1904) infection on the differential leukocyte count (DLC) as a measurable indicator of health in tortoise hosts. A total of 206 blood smears were analysed, including 181 from spur-thighed tortoises (Testudo graeca Linnaeus) and 25 from marginated tortoises (Testudo marginata Schoepff). Light microscopy was used to identify infected individuals, determine DLC, and quantify parasitaemia levels. Overall, H. mauritanica was detected in 125 of 181 (69%) T. graeca samples and 21 of 25 (84%) T. marginata samples. To assess whether infection influenced DLC, we statistically compared leukocyte profiles between infected and uninfected individuals. Additionally, we evaluated the effects of other factors, including host species, parasitaemia intensity, sex, age, and the month and year of blood collection. Wilcoxon rank-sum tests revealed that parasitaemia and age had a statistically significant effect on DLC in T. graeca. Further analysis using linear models showed a significant association between parasitaemia and DLC, specifically affecting azurophils in T. graeca and basophils in T. marginata. Nine T. graeca tortoises positive for H. mauritanica were co-infected with haemosporidian parasites of the genus Haemocystidium Castellani et Willey, 1904, specifically three with Haemocystidium anatolicum (Orkun et Güven, 2013) and six with Haemocystidium caucasicum (Krasilnikov, 1965). Although co-infection itself was not statistically significant, a separate analysis of Haemocystidium parasitaemia revealed a significant effect on lymphocyte DLC. Furthermore, the frequent presence of mitotic and polychromatophilous erythrocytes in H. mauritanica-infected tortoises suggests a potential increase in erythrocyte regeneration.
We report the fauna of the Acanthocephala of 120 Patagonian blennies Eleginops maclovinus (Cuvier) from northern Patagonia, Argentina. A total of 535 acanthocephalans belonging to five species were collected and identified using light microscopy. Juvenile and adult forms were only observed for Hypoechinorhynchus magellanicus Szidat, 1950 (Arhythmacanthidae). Juvenile forms of Corynosoma australe Johnston, 1937, Corynosoma cetaceum Johnston et Best, 1942 and Corynosoma shackletoni Zdzitowiecki, 1978 (Polymorphidae) were found encapsulated in the mesenteries. Juveniles of Profilicollis chasmagnathi (Holcman-Spector, Mañé-Garzón et Dei-Cas, 1977) (Polymorphidae) were found free in the intestines of the fish. Hypoechinorhynchus magellanicus was the most abundant acanthocephalan in our study, accounting for 48.4% of all specimens collected, followed by C. australe (33.5%). The Patagonian blennie represents a new host record for four species (C. australe, C. cetaceum, C. shackletoni and P. chasmagnathi). The northern Patagonia in Argentina is a novel locality record for C. shackletoni. This survey improves our knowledge of life cycles and geographical distribution of zoonotic marine acanthocephalans with potential risk to humans and companion animals.
Flagellated protozoa of the order Trichomonadida infect a variety of vertebrates, including poultry such as Gallus gallus domesticus (Linnaeus). Several trichomonad pathogens are of significant veterinary importance due to their role in diseases that cause high mortality rates in chickens. Despite the importance of Trichomonadida in poultry health, molecular studies on these protozoa in North Africa are limited. This study addresses this gap by investigating the genetic diversity and evolutionary relationships of Trichomonadida isolated from G. gallus domesticus and its nematode parasite Heterakis gallinarum (Schrank, 1788) in Tunisia, using a multilocus molecular approach with 18S rRNA and α-actinin 1 genes. Based on both markers, all Tunisian haplotypes, which clustered with those from France, were found to belong to genotype2. 18S rRNA analysis revealed the existence of protozoans such as Histomonas meleagridis (Smith, 1895) and Parahistomonas wenrichi Lund, 1963 in coinfection with H. gallinarum, confirming a possible mixed infection. Additionally, when analysing caecal samples, other Trichomonadida species were identified, including Simplicimonas sp. and Tetratrichomonas gallinarum (Martin et Robertson, 1911). These findings suggest a complex protozoan community within the studied hosts. Phylogenetic analysis revealed a close relationship between H. meleagridis and P. wenrichi, as well as between Simplicimonas sp. and the Monoceromonas-Tritrichomonas group. Both H. meleagridis genotypes 1 and 2 exhibited a sister-group relationship with P. wenrichi, with strong support for a common evolutionary origin. Tetratrichomonas gallinarum was basal in the tree, suggesting early divergence in the Trichomonadida lineage. This study provides, for the first time, insights into the genetic diversity of trichomonadids in Tunisia. The 18S rDNA locus proved to be effective for assessing the genetic diversity of H. meleagridis, P. wenrichi, T. gallinarum and Simplicimonas sp. and showed a possible mixed infection. The findings provide valuable insights into the genetic characteristics of these parasites in Tunisian poultry farms and contribute to the understanding of Trichomonadida diversity, enhancing disease control and prevention efforts.
The morphological variation of the nematode Raphidascaris mundeswariensis Patra, Choudhury, Thorn et Ash, 2021 in four fish hosts, Apocryptes bato (Hamilton), Glossogobius giuris (Hamilton), Taenioides cirratus (Blyth) and Eleotris lutea (Day), from the Mundeswari River of West Bengal, India, was studied. Partial sequences of the 28S rRNA and COI gene were generated to verify the conspecificity of these isolates while evaluating host-related variation in these samples. Little to no genetic variation was found among isolates from the different hosts and all were identified as R. mundeswariensis. However, subtle differences were found in the morphology among specimens of R. mundeswariensis from the four different hosts, mainly the number of caudal papillae and spicule length. The difference in the nematode morphology from various fish species can be a case of host-induced morphological variation which may enhance the adaptive capabilities of these helminths to parasitise a wide range of hosts. The present study raises questions about the use of the number of caudal papillae as an important taxonomic character in this species and other related nematodes. The results from this study also highlight the importance of examining as many specimens as possible from different hosts in the same localities to cover the range of intraspecific variation.
Three species of amphibian-parasitic acanthocephalans belonging to the genus Pseudoacanthocephalus Petrochenko, 1958 have been recorded in Japan. However, only a limited number of localities have been surveyed, and the distribution of these congeners across other regions of Japan remains unclear. In this study, acanthocephalans of the genus Pseudoacanthocephalus were recovered from both definitive (Rana ornativentris Werner - type host, and Zhangixalus arboreus [Okada et Kawano]) and accidental hosts (Scyliorhinus torazame [Tanaka]) from Sado Island, Japan. Morphological analyses indicate that those specimens represent a new species, Pseudoacanthocephalus sadoensis sp. n., which may be endemic to the island. Additionally, our report of the incidental occurrence of this species in a marine elasmobranch represents the first documented case of a Pseudoacanthocephalus species found in a marine host.
Our team's discovery of the link between chronic "latent" infection with Toxoplasma gondii (Nicolle et Manceaux, 1908) and suicidal behaviour, and our subsequent cross-diagnostic confirmatory work and mechanistic extensions, evolved from our neuroimmunology studies on affective and behavioural dysregulation exacerbated by allergic sensitisation and allergen exposure. Another root was studying behavioural changes and cytokine gene expression in the brain of rodents sensitised and exposed to aeroallergens. We "piggy-backed" our project funded to study coupling between aeroallergen sensitisation and exposure in patients with recurrent mood disorders, by measuring Toxoplasma gondii (T. gondii) antibodies in existing samples, and found associations between IgG serointensity and past suicide attempts. Successively, we then reported significant associations between T. gondii seropositivity and/or serointensity and suicidal behaviour in patients with schizophrenia in Germany, recent attempters in Sweden, and longitudinally in a cohort of Danish mothers. In the Danish mothers the exposure to T. gondii preceded self-directed harm and violent suicide attempts; the association was stronger with higher serointensity strata demonstrating a dose-effect. Furthermore, we identified links between T. gondii IgG and suicide endophenotypes of aggression and impulsivity in both individuals with no history of mental illness, and in patients with Intermittent Explosive Disorder (IED). We also found associations between T. gondii and risk factors of suicidal behaviour such as hopelessness and anhedonia in the Amish, depressive symptoms in pregnant women and women Veterans, frailty in older adults, and cognitive deficits in patients with bipolar disorder. Recently, we reported positive associations between T. gondii IgG serointensity with suicidal ideation, impulsivity, depression scores, and daytime dysfunction due to sleep problems in US Veterans who previously attempted suicide. Toxoplasma gondii emerged rather unexpectedly and then took over a considerable proportion of our neuroimmune research portfolio. It satisfied both intellectual appetites, and brought celebrations of discovery, with three systematic reviews and meta-analyses published to date, and a substantial majority of primary articles confirming our initial observations. Toxoplasma gondii also brought considerable frustrations, such as initial grant application setbacks, inability to completely demonstrate causality and, so far, prophylactic and therapeutic impotence for mental health applications in general. While we do not have, as of today, effective and safe treatments for chronic toxoplasmosis with demonstrated mental health benefits in immunocompetent hosts, there are reasons to be optimistic regarding future discoveries. These may include vaccines, novel medications using in silico exploration with biological confirmation, trials of reactivation prevention, as well as identification and targeting of mediating mechanisms. Yet the most justified reasons for optimism are the potential to apply machine learning (ML) and artificial intelligence (AI) methodologies to big data with a focus on interaction and causal inference. These novel approaches, utilising ML-weighted models that emulate randomised trials in electronic medical records, have the potential to reveal not only if T. gondii elevates risk and to what extent, but also for whom specifically, under which demographic, clinical and physiological circumstances, and what factors, or combinations thereof, might mitigate this risk.
Taenia crassiceps (Zeder, 1800), a zoonotic cestode with a wide geographical distribution, utilises canids as definitive hosts and small rodents as intermediate hosts. However, accidental infections in non-human primates, particularly in captive lemurs, have been increasingly documented. In this case report, we describe the first documented case of cysticercosis caused by the larval stage of T. crassiceps (metacestode; also known as Cysticercus longicollis Rudolphi, 1819) in a captive western grey bamboo lemur (Hapalemur occidentalis Rumpler). The affected female lemur showed progressive abdominal distension over a period of two months, which initially indicated pregnancy. At necropsy, multiple thin-walled metacestodes were discovered throughout the abdominal and thoracic cavities, including a large polycystic mass involving the liver and peritoneum. Histopathological analysis revealed larval cestodes with armed (hook-bearing) scoleces embedded in vascularised stromal tissue, accompanied by marked eosinophilic and macrophage infiltration and focal necrosis, particularly in the lungs. Morphological and molecular identification based on COI gene sequencing confirmed the presence of T. crassiceps. Despite extensive parasitological investigations, no definitive host excreting T. crassiceps eggs was found in the zoological facility where the lemur was kept. These results emphasise the possibility of indirect environmental transmission and highlight the susceptibility of lemurs as atypical intermediate hosts. This case confirms previous reports of lethal cysticercosis in lemurs, which is often characterised by rapid systemic spread of metacestodes. Our findings also emphasise the need for increased awareness and preventive measures to reduce the risk of parasite infections in vulnerable captive primates.
