Acta Parasitologica最新文献

This study reports the first confirmed occurrence of the ciliated protozoan Tetrahymena pyriformis infecting Nile tilapia (Oreochromis niloticus) in the Godavari Basin, India. It evaluates its pathological impact on fish health.

Between May 2024 and March 2025, a total of 314 fish were examined from Nanded and Parbhani districts. Infections were diagnosed through light microscopy using Giemsa (1:10) and silver nitrate (2%) staining, with ultrastructural features confirmed by scanning electron microscopy (SEM). Histopathological examinations of gills and skin were performed to assess tissue damage associated with parasitism.

Out of 314 examined fish, 96 (30.5%) were infected, primarily in the gills and skin. As a facultative parasite, T. pyriformis became opportunistically pathogenic under stress conditions, leading to tetrahymenosis. Histopathology revealed severe epithelial disruption, excessive mucus secretion, hemorrhagic lesions, and necrosis, indicating substantial pathological effects of the infection.

This first record of T. pyriformis in Nile tilapia from India highlights its pathogenic potential. It underscores the importance of routine parasitological monitoring in both wild and cultured populations to ensure fish health and sustainable aquaculture management.

Purpose

Eimeria bovis is a protozoan disease-causing coccidiosis, a which affects significantly on the global cattle industry. Nonetheless, the control measures implemented have not been entirely effective, thus prompting the search for alternative methods for the parasitic and/or environmental control of the infecting forms (sporulated oocysts). The study aimed to evaluate the effect of papaya (Carica papaya) latex and pure papain on both sporulated and non-sporulated E. bovis oocysts.

Methods

Oocysts were collected from the feces of calves previously inoculated with E. bovis and stored in a potassium dichromate solution. Subsequently, the oocysts were assessed for the application of aqueous solutions (both active and denatured) of latex and papain at concentrations of 10%, 15%, and 30% (w/v), alongside a control group (water), which were incubated at 28 °C for 48 h. A reduction in oocyst counts was observed in the treatments compared to the control group.

Results

However, a significant difference (p < 0.01) was noted only at the concentration of 30% papain (m/v) in relation to the control.

Conclusion

The findings suggest that extracts of C. papaya, rich in papain, hold considerable potential for future applications in the control of E. bovis.

Purpose

Visceral leishmaniasis (VL) is a serious health-threatening disease. Existing drugs are often toxic. So alternative treatments are constantly being considered and evaluated. This study aims to investigate Auranifin as potential new antileishmanial agent.

Methods

The fatality rate of different concentrations of auranofin (2, 4, 6, 8, 10, 12 μg/ml) on promastigote and amastigote forms after 24 h was calculated. The induction apoptosis in promastigotes by auranofin was also analyzed. Then, Leishmania-infected mice were treated with a concentration of 6.25 mg/kg and 12.5 mg/kg of Auranofin. After 1 month, the liver and spleen of the euthanized mice were separated, smears were prepared and pathology slides were prepared from the spleen and liver. Blood cell counts and liver and kidney enzymes were analyzed using heart blood. Histopathological examinations were performed on liver and spleen after treatment.

Results

The fatality rate of auranofin at a concentration of 12 µg/ml on promastigote and amastigote forms of Leishmania infantum 24 h after culture was 99.35% and 94.05%, respectively. Over 90% of promastigotes and amastigotes were killed at concentrations of 8 µg/ml and 12 µg/ml of auranofin, respectively. Flow cytometry showed a high apoptosis rate (93.73%) at a concentration of 12 μg/ml. In the control group (without auranofin) 99% of cells were alive. Histopathological examination of the spleen and liver tissues showed a decrease in the degree of granulomatous and inflammatory changes in the groups treated with auranofin. Blood factors as well as Liver and kidney enzymes showed changes in both the test and control groups.

Conclusion

Auranofin has anti-leishmanial properties in both promastigotes and amastigotes, further studies are neecessary to explore this aspect.

Purpose

This study aimed to identify and analyze the role of Ferric reductase inBlastocystis sp. subtype 2 (ST2) and explore the relationship between the parasite and iron metabolism.

Methods

The location of Ferric reductase in Blastocystis sp. was determined using the indirect immunofluorescence assay (IFA). Transmission electron microscopy was employed to reveal the effect of iron ions on the cell membrane of Blastocystis sp.. For the first time, RNA interference technology was used to explore the relationship between Ferric reductase and iron ions.

Results

Ferric reductase was distributed in the membrane and cytoplasm of the parasite. Iron reduces the thickness of the Blastocystis sp.'s cell membrane. After silencing the Ferric reductase gene, there was no significant difference in the morphology of the parasite strain compared with the control group. The expression level of the Ferric reductase gene does not play a decisive role in maintaining the morphology of the parasite, but the deletion of the Ferric reductase gene reduces the ability of the parasite to absorb iron ions.

Conclusions

This study fills the gap in the research field of iron metabolism inBlastocystis sp. among parasites, lays a foundation for the research on the gene function of Blastocystis sp., and provides new candidate factors for the development of Blastocystis sp. vaccines.

Introduction

The objective of the World Health Organization is to achieve the interruption of human African trypanosomiasis (HAT) transmission by 2030.

Methods

This review aims to update knowledge on HAT, through a synthesis on the epidemiology, diagnostic tools and drugs of HAT.

Results

From 1960 to 2024 approximately 132,063 cases of HAT have been reported across Africa. The majority of HAT patients live in the Democratic Republic of Congo (DRC). The Card Agglutination Test for Trypanosomiasis (CATT) remained for a long time the reference serology test for field screening. The immune trypanolysis test (ITL) test is an accurate serodiagnostic tool increasingly used for medical surveillance of sleeping sickness, but it is reserved for reference laboratories. Prototypes of TDRs such as SD BIOLINE HAT and, HAT Sero-K-SeT have been developed to respond to constraints posed with CATT and ITL, but lack specificity. Parasitological diagnosis techniques such as the mini-Anion Exchange by Centrifugation technique (mAECT) are used for mandatory confirmation of the disease before the initiation of treatment, but their sensitivity is low. To date, the active molecules against HAT are: pentamidine, suramin, melarsoprol, eflornithine and nifurtimox. The use of these molecules does not guarantee healing and generates many side effects. A new molecule has appeared in the therapeutic arsenal. This is fexinidazole, which was approved by the WHO in 2019 for the treatment of HAT due to T.b. gambiense. The WHO recommends the oral administration of this molecule in the first stage of the disease and in the second stage for non-severe cases. Since 2024, this molecule has also been approved by the WHO for the treatment of HAT due to T. b. rhodesiense.

Conclusion

All these difficulties raised raise questions about the need to develop new diagnostic tools that are more specific, more sensitive and better suited to field screening. They also call out the urgency of finding new drugs that are less toxic, easy to administer and more effective.

Toxoplasma gondii, as an obligatory intracellular protozoan, can infect a diverse array of individuals and warm-blooded creatures. Considering the worldwide public health implications caused by T. gondii infection, it is an important goal to develop effective diagnostic tests or vaccines. The application of natural antigens derived from the parasite in these assessments encounters challenges, including the complexities of culturing the parasites, strain differences, and the high cost of kits produced based on natural antigens. The current bioinformatic study aimed to develop a multi-epitope T. gondii protein based on various immunoinformatic web servers to improve serodiagnosis. The linear and conformational B-cell epitope prediction of Surface Antigens 1(SAG1) and 2(SAG2), Dense granule proteins 2 (GRA2), 6 (GRA6), and 7 (GRA7), was conducted by the ABCpred and BepiPred servers, respectively. A variety of web servers were then accessed to predict antigenicity, solubility, and physicochemical properties, as well as to analyze secondary and tertiary structures, refine the 3D model, and validate the findings. Consequently, conformational B-cell epitopes were identified to explore potential protein-antibody interactions. In conclusion, further experimental evaluation is necessary for this multi-epitope construct for its subsequent incorporation in commercial serodiagnostic kits.

Purpose

Taenia pisiformis cysticerci have been reported in the female reproductive tract of rabbits, and this parasitosis is known to alter reproductive behavior and reduce embryo implantation; however, tissue-based studies relating the immune system to the implantation site during infection have not been previously addressed. Therefore, our research provides new information on the interaction between pregnancy and parasitic infection.

Methods

This study evaluated the recruitment of immune cells in uterine tissue during T. pisiformis infection. Fourteen female rabbits were experimentally infected with 1,000 T. pisiformis eggs and mated with a male on day 50 post-infection. Eight days after mating—corresponding to the mesometrial stage of implantation— tissue samples were collected from the middle third of the right uterine horn at the site of embryonic implantation, following the sampling rationale described in previous literature. Samples were fixed and processed using paraffin-embedding techniques, and histological sections were stained with hematoxylin and eosin. Three sections per rabbit were analyzed across 18 fields per group, each field measuring 2,960 μm². Mucosal height was measured, and lymphocytes and macrophages were quantified in the mucosa based on morphological criteria.

Results

The results showed a significant increase in lymphocyte and macrophage infiltration at the implantation sites of infected does compared to controls (p < 0.05), along with a 49% increase in mucosal height. No cysticerci were found in the uterine tissue, but metacestodes were observed in the pelvic region in 33% of infected animals, with a mean of 3.1 ± 2.6 cysticerci per animal.

Conclusion

These findings suggest an increased immune cell infiltration and marked uterine mucosal remodeling in infected does, potentially interfering with embryo establishment and development. We acknowledge that hormonal and cytokine measurements were not performed in this study; therefore, future research should address these parameters to clarify the underlying mechanisms.

Background

The whole plant of Evolvulus nummularius is traditionally used to treat helminth infections in Assam, India. This study was taken to evaluate the efficacy of its methanolic extract in suitable models in vitro and in vivo.

Methods

Hymenolepis diminuta exposed in vitro to E. nummularius were also studied for damages to its tegument using scanning electron microscopy. Also, the plant extract’s ability to inhibit AChE activity was assessed. The extract was later processed for GC-MS analysis to detect the phytocompounds present.

Results

In vitro study showed significant efficacy against H. diminuta and in vivo study revealed 76.93% and 71% reduction in eggs and worm counts respectively against juvenile H. diminuta worms, whereas, the extract caused 80% and 79.25% reduction in these parameters against H. diminuta adult worms. The extract also showed to cause 55.73% reduction in AChE activity. H. diminuta worms exposed to plant extract showed deformities in the suckers, tegument, microtriches and suckers. Its GC-MS study revealed the presence of (-)-deoxyephedrine, methamphetamine, 1-(5-methoxy-2-methylphenyl)-N-methylpropan-2-amine, ethyl vanillin, 3,4-dihydroxypropiophenone, and 1-(1,4-cyclohexadienyl)-2-methylaminopropane.

Conclusion

The results infer that E. nummularius possess significant anthelmintic activity and may be used in traditional medicine.

Introduction

This study aimed to investigate the influence of benznidazole (BZN) origin on its in vitro potency against various Trypanosoma cruzi strains.

Methods

Pure BZN, purified BZN, and the pharmaceutical formulation Abarax were evaluated for their activity against several parasite strains.

Results

Results demonstrated significant variability in BZN’s effectiveness, contingent upon both its specific form and the T. cruzi strain under investigation. Half-maximal inhibitory concentrations (IC₅₀ values) exhibited a wide range, indicating that the potency of BZN is not uniform across all its forms or against all parasite strains.

Conclusion

In conclusion, this study elucidates the complex interaction between BZN and T. cruzi. The parasite’s response to BZN can vary even within a single strain, influenced by the drug’s specific presentation. These findings underscore the critical importance of considering both parasite diversity and drug formulation when assessing the efficacy of treatments in laboratory assays.

Purpose

Molecular epidemiological studies focusing on the phylogenetic characterization of Theileria annulata are crucial for understanding the evolutionary history of the parasite worldwide. The current study reveals genetic diversity among Indian isolates of T. annulata based on the cyt b gene.

Method

In the present study, cyt b gene from 6 calf isolates of T. annulata was amplified; custom sequenced and accession numbers: MH778940-MH778945 were obtained.

Result

Two haplotypes were identified, differing by nucleotide substitutions at positions 710 (thymine to adenine) and 1076 (cytosine to guanine). Isolates from Northern India formed a distinct cluster on the phylogenetic tree compared to those from Southern India and showed closer phylogenetic similarity to Iranian isolates than to other Asian counterparts.

Conclusion

Important phylogenetic data has been generated from the present study suggestive of marked genetic variability in T. annulata isolates across the globe.