Parasitologia, Volume 5, Issue 4 (December 2025) – 10 articles

Our study reports the first molecular detection of the protozoan pathogen Histomonas meleagridis, the causative agent of histomonosis, in the poultry red mite Dermanyssus gallinae. Mite samples were collected from a commercial poultry farm and a backyard flock in Hungary and analyzed using PCR assays that targeted the COX1 gene in mites and 18S rRNA gene in H. meleagridis. Phylogenetic analysis confirmed the identity of D. gallinae and revealed distinct genetic lineages between farm and backyard isolates. H. meleagridis DNA was detected in 10 of 17 mite samples, representing multiple variants within Genotype 1. No histomonosis was detected in the examined poultry, although one hen harbored Simplicimonas sp. The findings suggest that D. gallinae could serve as a carrier for H. meleagridis, potentially facilitating the persistence and transmission of the pathogen. This novel host–pathogen association highlights the need for further research into the epidemiological role of poultry ectoparasites in the spread of histomonosis. Full article

Helminth parasites infect mammalian hosts through complex life cycles, mostly triggering T helper type 2 (Th2) immune responses characterized by interleukin-4 (IL4), interleukin-5 (IL5), and interleukin-13 (IL13) production. Environmental chemical exposures may modulate these immune pathways, potentially affecting infection outcomes. Using The Comparative Toxicogenomics Database (CTD), we analyzed chemical–gene interactions affecting IL4, IL5, and IL13 genes to identify chemicals capable of modulating Th2 immunity and their associated expression profiles. Accordingly, a total of 818 chemicals can interact with IL4, IL5 and/or IL13, with 145 chemicals showing the potential of affecting all three genes. These 145 chemicals include air pollutants (8.3%), allergens (2.7%), bioactive molecules (8.3%), industry-related chemicals (14.5%), medicinal drugs (21.4%), metal and metal-containing chemicals (8.3%), pesticides (3.4%), plant compounds (12.4%), and others (20.7%). We observed a greater number of chemicals associated with increased (n = 95) gene expression compared to decreased (n = 14) gene expression, suggesting a Th2 pathway hyperactivation caused by chemicals capable of affecting IL4, IL5 and IL13. Eight classes of parasitic diseases were observed among chemical-associated conditions. Environmental chemicals extensively modulate Th2 immune responses through diverse molecular mechanisms. The trend concerning upregulation of Th2 pathways may enhance antiparasitic protection but, on the other hand, could predispose individuals to allergic diseases, among other Th2-related conditions. These exploratory findings suggest that chemical pollution may influence the susceptibility and pathogenesis of helminth infections and highlight the need for the incorporation of exposome-based approaches in parasitology research. Full article

Pediculosis produced by the presence of the human head louse (Pediculus humanus capitis DeGeer, 1767) and the body louse (Pediculus humanus humanus L., 1758) remains a neglected tropical disease in Nigeria, where permethrin-based pediculicides are widely used. However, the resistance status of lice populations has not been previously assessed. Knockdown resistance (kdr) to pyrethroids is primarily driven by two mutations—T917I and L920F—in the voltage-sensitive sodium channel (VSSC) gene. This study investigated the presence of these mutations in 85 head and body lice collected from school-age children in two settlements in Nigeria. The T917I mutation was detected in head lice at frequencies ranging from 21% to 76%, and in body lice from 10% to 95%, with significant variation between sites and louse types. Remarkably, all lice examined carried the L920F mutation, regardless of T917I genotype, a pattern not previously reported in body lice. These findings suggest that pyrethroid resistance is well established or under active selection in the study populations. This is the first report of kdr mutations in human lice from Nigeria and highlights the urgent need for resistance monitoring programs. Early genetic surveillance of these mutations can inform treatment strategies and help prevent widespread resistance in lice populations, preserving the efficacy of available pediculicides. Full article

The increasing global incidence of infections caused by free-living amoebae (FLA) and the lack of effective, safe, and approved treatments highlight the urgent need for novel amoebicidal compounds with pharmacological potential. Despite a growing body of literature on the anti-FLA properties of various compounds, comprehensive reviews summarizing this progress remain scarce. This study aimed to identify the most promising compounds tested in vitro and/or in vivo for anti-FLA activity. A systematic review was conducted, analyzing 108 studies published between 1986 and 2024, selected from an initial pool of 23,653 database results. A total of 537 compounds were evaluated for their in vitro anti-FLA activity. Compounds exhibiting ≥50% reduction in amoeba viability relative to untreated controls were classified as promising if they showed low toxicity in mammalian cell models, particularly when active at concentrations ≤ 10 µM, consistent with predicted favorable pharmacokinetic and pharmacodynamic profiles. The most promising compounds for drug and disinfectant development include ten trophocidal agents against B. mandrillaris, thirty-two trophocidal and four cysticidal agents against N. fowleri, and sixty-two trophocidal and nineteen cysticidal agents against Acanthamoeba spp. Compounds active at low concentrations (≤10 µM or <0.014 mg/mL) prioritized for in vivo drug development studies include: against Balamuthia mandrillaris, trophocidal 515, 531, 533; against Naegleria fowleri, trophocidal 421, 416, 518, 46, 254, 522, 111–120 and cysticidal 16; and against Acanthamoeba spp., trophocidal 498, 499, 500, 535, 107, 347, 348, and 340. Future studies should evaluate their efficacy, safety, pharmacokinetics, and pharmacodynamics toward developing effective drugs, antiseptics, and disinfectants. Full article

The main pathological, epidemiological, and clinical findings of haemonchosis in goats and sheep in a semi-arid region of Northeast Brazil are described. Necropsy records conducted between January 2012 and December 2021 at the Animal Pathology Laboratory (APL) of the UFCG, were reviewed. In 2022, a prospective study monitored the necropsies performed on these species. In total, necropsies were conducted on 410 goats and 319 sheep, haemonchosis was observed in 50 (12%) goats and 49 (15%) sheep. For goats, females (45/50, 90%; p ≤ 0.05), the age range of 13–35 months (25/50, 50%; p ≤ 0.05), and crossbred animals (38/50, 76%; p ≤ 0.05) were most affected. Both goat and sheep, respectively, raised in a semi-intensive system were more infected (41/50, 82%; 36/49, 76.5%; p ≤ 0.05). The animals came from the States of Paraíba, Pernambuco, Ceará, and Rio Grande do Norte. The proportion of goats (32/50, 64%) and sheep (30/49, 61.2%) with a normal body condition score was significantly different (p ≤ 0.05). The main pathological alterations (p ≤ 0.05) were the mucosal and carcass paleness, and the presence of H. contortus specimens in the abomasum. Haemonchosis remains a significant parasitic disease affecting small ruminants in the semi-arid region of Northeast Brazil, leading to mortality and decreased production rates, posing substantial economic challenges that adversely impact goat and sheep farming. Full article

Excretory/secretory products from parasites (ESPs) can act as pathogen-associated molecular patterns (PAMPs) to activate innate immunity. Parasites may achieve immune evasion by modulating the interaction between PAMPs and the nucleotide-binding oligomerization domain-like receptor family, pyrin domain-containing three (NLRP3) inflammasome. Previous studies have suggested that some components of ESPs from Clonorchis sinensis (CsESPs) can induce the host’s immune responses, but the components that balance immunopathology and maintain chronic infection in chronic Clonorchis sinensis (C. sinensis) remain unclear. We previously found that the iNOS-interacting protein from C. sinensis (CsNOSIP), a component of CsESP, stimulates macrophages to produce reactive oxygen species (ROS) and nitric oxide (NO), both of which inhibit NLRP3 inflammasome activation. Therefore, this study investigated the effects of CsESP and CsNOSIP on inflammasome activation using RT-PCR, Western blot, and ELISA. This study showed that CsESPs promoted NLRP3 inflammasome activation in RAW264.7 cells, while CsNOSIP inhibited LPS-induced IL-1β secretion through an NLRP3-caspase-1-dependent pathway and reversed the CsESPs-induced activation through the iNOS/NO–NF-κB pathway. These results reveal the antagonistic effects of CsESPs and CsNOSIP in inflammasome regulation, suggesting that this balance contributes to the regulation of the host’s immunity and the promotion of chronic infection of C. sinensis, providing potential targets for prevention and treatment. Full article

African trypanosomiasis is a protozoan disease that affects both humans and animals. Human African Trypanosomiasis (HAT) is a Neglected Tropical Disease targeted for elimination in 2030. Although WHO has not reported HAT from Nigeria in the last decade, there are published studies reporting seroprevalence, parasite detection/isolation, and animal reservoirs potentially involved in HAT transmission in Nigeria. Interestingly, the burden of Animal African Trypanosomiasis (AAT) continues to increase. In this study, we synthesized published reports on the prevalence of HAT and AAT in Nigeria from 1993–2021, the trypanosome species involved, the spread of animal reservoirs, and the variability in diagnostic methodologies employed. A scoping review was performed following the methodological framework outlined in PRISMA-ScR checklist. Sixteen eligible studies published between 1993 and 2021 were reviewed: 13 for AAT and 3 for HAT. Varying prevalence rates were recorded depending on the diagnostic methods employed. The average prevalence reported from these studies was 3.3% (HAT), and 27.3% (AAT). Diagnostic methods employed include microscopy, PCR and Card Agglutination Test for Trypanosomiasis (CATT). Cattle, pigs, and dogs were identified as carriers of human-infective trypanosomes. This study highlights the scarcity of HAT epidemiological studies/data from Nigeria, the high prevalence, complex epidemiology, limited attention and surveillance of African Trypanosomiasis in Nigeria. Remarkably, WHO records do not reflect the published data showing evidence of HAT prevalence/cases in Nigeria. Unfortunately, diagnostics challenges and unrealistic disease reporting protocols seem to limit HAT reporting from Nigeria. Therefore, adequately coordinated epidemiological surveys and targeted intervention policies are imperative to ascertain the true epidemiological status of HAT in Nigeria and prevent disease re-emergence towards achieving WHO’s elimination targets. The presence of animal carriers of human-infective trypanosomes underscores the importance of a one-health approach to combat African trypanosomiasis effectively. Full article

Stomoxys calcitrans (Linnaeus, 1758) is a hematophagous fly species of veterinary importance, known for its negative effects on animal health and productivity. The stress caused by their painful bites results in losses in milk and meat production. Despite its impact, data on its ecology and activity in Algeria are lacking. Such knowledge is needed to evaluate its potential effects on livestock production and rural health, and to support surveillance, outbreak prediction, and control strategies. This study aimed to investigate the monthly and daily dynamics of S. calcitrans in livestock farms in the Batna region and evaluate the influence of climatic factors on its abundance. From July 2022 to July 2023, Vavoua traps were placed monthly from 7 a.m. to 6 p.m. on four farms in the Batna region, representing different livestock types. Captured flies were identified, sexed, and counted every two hours. Climatic data were collected both in situ and from NASA POWER datasets. Fly abundance was analyzed using non-parametric statistics, Spearman’s correlation, and multiple regression analysis. A total of 1244 S. calcitrans were captured, mainly from cattle farms. Activity occurred from August to December, with a peak in September. Males were more abundant and exhibited a bimodal activity in September. Fly abundance was positively correlated with temperature and precipitation and negatively correlated with wind speed and humidity. This study presents the first ecological data on S. calcitrans in northeastern Algeria, highlighting its seasonal dynamics and the climatic drivers that influence it. The results highlight the species’ preference for cattle and indicate that temperature and rainfall are key factors influencing its abundance. These findings lay the groundwork for targeted control strategies against this neglected pest in Algeria. Full article

Human subcutaneous dirofilariasis caused by Dirofilaria repens is an emerging zoonotic parasitic infection increasingly observed in southern Europe. We report a case of a woman from western Sicily, who likely acquired the infection locally through a mosquito bite. The high prevalence of D. repens in the local canine population (up to 20.4%) suggests a role of dogs as a probable reservoir for transmission to humans in the local population. With ultrasound analysis being inconclusive, only after surgical removal was the presence of an adult worm evident, and only after molecular analysis through DNA sequencing of the cytochrome oxidase subunit I gene (COI) could a definitive D. repens infection diagnosis be obtained. This case highlights the need for enhanced vector control, animal health surveillance and public awareness to limit the transmission to humans of D. repens. A correct parasitological diagnosis would be imperative for the recognition of human cases. Full article

In this study, a diverse collection of images of myxozoans from the genera Henneguya and Myxobolus was created, providing a practical dataset for application in computer vision. Four versions of the YOLOv5 network were tested, achieving an average precision of 97.9%, a recall of 96.7%, and an F1 score of 97%, demonstrating the effectiveness of MLens in the automatic detection of these parasites. These results indicated that machine learning has the potential to make microparasite detection more efficient and less reliant on manual work in parasitology. The beta version of the MLens showed strong performance, and future improvements may include fine-tuning the WebApp hyperparameters, expanding to other myxosporean genera, and refining the model to handle more complex optical microscopy scenarios. This work presented a significant advancement, opening new possibilities for the application of machine learning in parasitology and substantially accelerating parasite detection. Full article