Parasitologia, Volume 6, Issue 2 (April 2026) – 11 articles

Cholangiocarcinoma (CCA) is an aggressive malignancy with a poor prognosis that is strongly associated with chronic Clonorchis sinensis (C. sinensis, Cs) infection; however, its underlying molecular mechanisms remain elusive. Recent studies suggest that C. sinensis-derived extracellular vesicles (CsEVs) play a crucial role in host–parasite interactions and in shaping the tumor microenvironment during infection. Acting as key delivery vehicles, these CsEVs can transfer specific functional molecules, such as microRNAs (miRNAs), to host cholangiocytes, thereby modulating cellular behaviors—a process that may represent a significant pathway in parasite-induced carcinogenesis. Despite this, the specific miRNAs shuttled by CsEVs and their concrete functions and mechanisms in driving CCA proliferation and metastasis remain largely unexplored. To this end, we investigated Csi-miR-125a, a miRNA abundantly expressed in CsEVs, aiming to systematically elucidate its dual regulatory functions in CCA progression. Our findings offer novel mechanistic insights into host–parasite crosstalk, further the understanding of CCA pathogenesis, and point to potential therapeutic avenues. Using gain-and loss-of-function approaches in RBE and HuCCT1 cell lines, we demonstrated that Csi-miR-125a promotes cell proliferation by accelerating cell-cycle progression and suppressing apoptosis through direct targeting of BAK1. Concurrently, Csi-miR-125a enhances the migratory and invasive capacities of CCA cells via activation of the ERK signaling pathway. In a BALB/c nude mouse lung metastasis model, CsEVs depleted of Csi-miR-125a significantly inhibited pulmonary metastasis. Collectively, This study found that Csi-miR-125a derived from C. sinensis can regulate apoptosis and cell cycle progression by targeting BAK1, thereby promoting the proliferation of cholangiocarcinoma cells; meanwhile, it enhances cell migration and invasion by activating the ERK signaling pathway. These results suggest that Csi-miR-125a participates in and promotes the malignant progression of CCA. However, given its high homology with human endogenous miR-125a, its function may partially overlap with host endogenous miRNAs, rather than representing a completely independent carcinogenic effect. These findings provide mechanistic insights into host–parasite interactions during C. sinensis infection and lay a theoretical foundation for subsequent targeted intervention studies. Full article

Urban coastal wetlands constitute important ecological interfaces where human activities, wildlife, and arthropod vectors interact, potentially increasing the risk of pathogen transmission. In the city of Veracruz, Mexico, several interdunal lagoons have been incorporated into urban areas and are intensively used for recreational activities; however, information on their mosquito fauna remains limited. This study aimed to characterize mosquito species composition, abundance, and diversity in three urban recreational interdunal lagoons in Veracruz. Adult mosquitoes were collected weekly during the rainy season (June–September) 2023 using CDC light traps. Specimens were identified based on morphological characters using standard taxonomic keys, including genitalia dissections for male specimens when necessary. Species richness, sampling completeness, and community structure were evaluated using non-parametric richness estimators, diversity indices, species accumulation curves, and similarity analyses. A total of 1465 adult mosquitoes belonging to 11 species and five genera were collected. Mosquito assemblages were characterized by low species richness and a marked dominance of Culex panocossa and Culex quinquefasciatus across all lagoons. Diversity indices were low, and species composition showed a high degree of similarity among sites. Notably, Uranotaenia apicalis was recorded for the first time in the state of Veracruz, expanding its known geographical distribution. These findings indicate that urban interdunal lagoons support simplified mosquito communities dominated by disturbance-tolerant species, highlighting their potential epidemiological relevance and the need for targeted vector surveillance in urban coastal environments. Full article

During August 2025, a single adult yellow-bellied watersnake, Nerodia erythrogaster transversa was found dead on the road in Montgomery County, Arkansas, USA, salvaged, and its feces examined for coccidian parasites. Fecal material from the rectum was placed in a vial of 2.5% potassium dichromate and examined by light microscopy. Partially sporulated oocysts were initially found and allowed to completely sporulate. The snake was found to be passing a new species of Eimeria. Oocysts of Eimeria speairsi sp. n. were ovoidal to spheroidal with a slightly rough bi-layered wall, measured (L × W) 28.0 × 18.2 µm, and had a length/width (L/W) ratio of 1.5; a micropyle, oocyst residuum, and polar granule was absent. Sporocysts are ellipsoidal and measured 13.7 × 8.6 µm, L/W ratio of 1.6; a flattened Stieda body was present but sub-Stieda and para-Stieda bodies were absent. The sporocyst residuum was composed of various-sized granules in a compact rounded or irregular mass, sometimes dispersed between the sporozoites. A 412 bp sequence of the SSU rRNA gene produced for E. speairsi sp. n. showed a relatively low level of similarity. The species description is based primarily on oocyst morphology and partial SSU rRNA sequence data from the single host snake. In addition, an updated summary of the coccidians of North American watersnakes is provided. Full article

Cutaneous larva migrans (CLM) is a zoonotic parasitic infection traditionally associated with tropical and subtropical regions. In recent years, autochthonous cases have been reported in various European countries, suggesting a possible change in the epidemiological profile of the disease. We present a case of a patient with no history of international travel who developed a typical serpiginous, migrating skin lesion after local exposure. The diagnosis was made clinically, and treatment with albendazole resulted in rapid clinical improvement. To our knowledge, this is the first published probable autochthonous case of CLM in Bulgaria. The case highlights the role of climate change in expanding the geographical scope of the parasitosis and the need for increased clinical vigilance at the primary care level. Full article

Schistosomiasis is a major neglected tropical disease in sub-Saharan Africa. This study compared the epidemiology of urinary schistosomiasis among children living in two distinct ecosystems in Mauritania: the Senegal River Basin (Trarza region) and the arid oasis areas (Adrar and Tagant regions). A cross-sectional study was conducted between February 2023 and February 2024 involving 856 children across 14 sites. Urine samples were collected from school-aged children and subjected to macroscopic and microscopic examinations. A questionnaire was administered to each child to determine sociodemographic factors. Environmental and geographical factors were documented in the localities. The prevalence rate of urinary schistosomiasis among children in the Senegal River Valley was 32.4%. In the oases zone, prevalences were 6.43% and 3.35% in Tagant and Adrar, respectively. Macroscopic hematuria was 29.1%, 6.04%, and 4.18% in Trarza, Adrar, and Tagant, respectively. The intensities of infection were 48.9, 6.43, and 40 eggs/10 mL in the Trarza, Adrar, and Tagant regions, respectively. Based on sex, prevalence was higher among boys in the Trarza and Tagant regions, while in Adrar, it was higher among girls. Prevalence among children using polluted water sources with dense vegetation in the department of Tékane, in the Trarza region, was significantly higher (35.7%) than among those using cleaner water sources (21%). Urinary schistosomiasis remains highly prevalent among children living along the Senegal River, while considerably lower transmission was observed in oasis settings. These findings highlight the strong influence of environmental and water-related factors on transmission dynamics and underscore the need for targeted, context-specific control strategies. Full article

Objective: To evaluate the diagnostic performance of an in-house-developed IgG Western blot (WB) for congenital toxoplasmosis and its complementary role with other serological markers. Methodology: For this purpose, the study utilized 42 mother–child pairs, evaluating the WB in comparison with a Composite Reference Standard (CRS). Cohen’s Kappa coefficient measured agreement, while McNemar’s test compared WB with Combined Serology (neonatal IgG titers higher than the mother’s (IgG↑), IgM, IgA). Results: The WB demonstrated a sensitivity of 75.0% and a specificity of 100.0%. Kappa indicated substantial agreement with the CRS (κ = 0.67; 95% CI: 0.44–0.89). McNemar’s test found no statistically significant difference between WB and Combined Serology (p = 0.7516). Crucially, WB detected 4 unique cases missed by Combined Serology, and Combined Serology detected 6 cases missed by WB. This complementarity increased the overall diagnostic rate from 82.14% to 96.43%. Conclusions: IgG-WB is a crucial complementary diagnostic tool, especially for asymptomatic newborns. Its integration significantly improves diagnostic certainty, allowing for more timely treatment for congenital toxoplasmosis. Full article

Leishmaniases are infections caused by Leishmania parasites and transmitted through the bite of infected female Phlebotomus (Old World) and Lutzomyia (New World) sandflies. The disease disproportionately affects marginalized communities with limited healthcare access. With no approved human vaccines available, leishmaniasis treatment and prevention depend heavily on chemotherapeutics that face growing drug resistance challenges alongside toxicity concerns. The development of safe, effective and affordable vaccines against human leishmaniasis remains a global health priority for disease control and elimination, mostly in resource-limited settings. This review synthesizes progress in leishmaniasis vaccine platforms including live-attenuated parasites, whole-killed parasites, DNA, protein subunit, peptide-based and chimeric/multiepitope vaccines and their homogenous and heterogenous efficacy. Live-attenuated and whole-parasite vaccines have been accounted to elicit robust cellular immunity but pose safety risks, particularly in immunocompromised hosts. While both second- and third-generation vaccines exemplified by LEISH-F1/F3 polyproteins, elicit strong Th1-biased T cell responses in preclinical models, their efficacy in humans remains limited. However, the highlighted collective efforts are pivotal in steering the rational development of future research using various formulations for multiple management of leishmaniasis through cross-protection. Furthermore, emerging strategies including mRNA platforms, nanoparticle delivery, reverse vaccinology, and immunoinformatics offer promising avenues for accelerating vaccine discovery and advancing the development of novel and effective human vaccines. Full article

Canine babesiosis is a vector-borne disease of dogs with a worldwide distribution, presenting varying clinical signs depending on the host, parasite strain and climatic factors. Beyond companionship, dog meat serves as delicacy and is also used for zootherapy in some African communities. In this study, we collated and analyzed molecular biology-based diagnostic data on Babesia species of dogs in Africa in order to elucidate the epidemiological factors of the disease on the continent. Four Babesia species—B. rossi, B. vogeli, B. gibsoni and B. canis—were detected in Africa based on the results from 40 studies that involved the screening of 9435 dog blood samples from 83 study locations. Babesia rossi was the most commonly reported (aggregate detection rate = 7.7%) and was detected in samples from all the African regions except northern Africa. Babesia vogeli was the second most commonly reported (aggregate detection = 4.8%) and was detected in all of the African sub-regions. There were few reports of B. gibsoni (0.6%) in the southern and western African regions, and a single case of B. canis in an untraveled Nigerian dog. So far, there were no reports of Babesia coco, Babesia conradae or Babesia vulpes (Babesia annae, Babesia microti-like) in any of the African countries that have been confirmed by a molecular method. This study presents a synopsis of canine babesiosis in Africa, and provides an overview of common clinical signs, etiologies and risk factors that will serve as a quick guide to veterinarians to achieve timely tentative diagnosis. Full article

In this study, the ultrastructural characteristics of the mature spermatozoon of the cestode Gerbillitaenia psammomi, a parasite of the fat sand rat (Psammomys obesus) in the south of Tunisia, were examined by means of transmission electron microscopy. The spermatozoon is of Levron et al.’s type VI. This type of sperm cell is mainly characterized by the presence of a single axoneme of the 9 + ‘1’ pattern typical of the trepaxonematan Platyhelminthes, crest-like bodies, a periaxonemal sheath, twisted cortical microtubules, and a spiraled nucleus. The spermatozoon of G. psammomi possesses two crest-like bodies of different length. The results obtained in the present study suggest certain similarities with the remaining analyzed catenotaeniids; namely, Catenotaenia pusilla, Skrjabinotaenia (Meggittina) gerbilli, and Spasskijela lobata. The results are compared and discussed according to several characteristics found in the catenotaeniids and other studied cestodes, particularly those of the order Cyclophyllidea. Full article

Acute Trypanosoma cruzi infection induces an exuberant immune response; however, the host is unable to clear the parasite, and the infection progresses to a chronic phase. T and B cells play a crucial role in controlling infections. Although the parasite constitutes a myriad of antigenic determinants capable of activating many T and B cell clones, some antigens trigger a large proportion of CD8 T cells, implying TCR cross-reactivity targeting these determinants. Polyclonal activation may result in an inefficient immune response against the parasite, diverting it to less critical antigenic determinants, allowing infection persistence, and increasing the risk of autoimmunity. Cross-reactivity has been demonstrated in CD8 T cells but not in CD4 T cells. Herein, we demonstrate, by cytometry, that CD4+ T cells, carrying the DO11.10 transgenic TCR, which are responsive to OVA, are activated during the T. cruzi acute infection, becoming effector memory T cells that produce cytokines such as IFN-γ, TNF-α, IL-4, and IL-10. In addition, prior oral exposure to OVA altered cytokine production by these transgenic T cells upon infection. We also demonstrate that T. cruzi induces Foxp3 expression in a sizable pool of transgenic T cells. Full article