Neutrophils versus Protozoan Parasites: Plasmodium, Trichomonas, Leishmania, Trypanosoma, and Entameoba

Neutrophils are the most abundant polymorphonuclear granular leukocytes in human blood and are an essential part of the innate immune system. Neutrophils are efficient cells that eliminate pathogenic bacteria and fungi, but their role in dealing with protozoan parasitic infections remains controversial. At sites of protozoan parasite infections, a large number of infiltrating neutrophils is observed, suggesting that neutrophils are important cells for controlling the infection. Yet, in most cases, there is also a strong inflammatory response that can provoke tissue damage. Diseases like malaria, trichomoniasis, leishmaniasis, Chagas disease, and amoebiasis affect millions of people globally. In this review, we summarize these protozoan diseases and describe the novel view on how neutrophils are involved in protection from these parasites. Also, we present recent evidence that neutrophils play a double role in these infections participating both in control of the parasite and in the pathogenesis of the disease.

Deciphering protein prenylation in endocytic trafficking in Toxoplasma gondii

Toxoplasma gondii is a widespread intracellular protozoan pathogen infecting virtually all warm-blooded animals. This parasite acquires host-derived resources to support its replication inside a membrane-bound parasitophorous vacuole within infected host cells. Previous research has discovered that Toxoplasma actively endocytoses host proteins and transports them to a lysosome-equivalent structure for digestion. However, few molecular determinants required for trafficking of host-derived material within the parasite were known. A recent study (Q.-Q. Wang, M. Sun, T. Tang, D.-H. Lai, et al., mBio 14:e01309-23, 2023, https://doi.org/10.1128/mbio.01309-23) identified a critical role for membrane anchoring of proteins via prenylation in the trafficking of endocytosed host proteins by Toxoplasma, including an essential Toxoplasma ortholog of Rab1B. The authors also found that TgRab1 is crucial for protein trafficking of the rhoptry secretory organelles, indicating a dual role in endocytic and exocytic protein trafficking. This study sets the stage for further dissecting endomembrane trafficking in Toxoplasma, along with potentially exploiting protein prenylation as a target for therapeutic development.

Molecular Survey of Haemosporidian Parasites in Procellariiformes Sampled in Southern Brazil, 2013-22

The order Procellariiformes includes several species of seabirds that perform long-distance migrations crossing all the oceans. These movements may contribute to the dispersal and exchange of hemoparasites, such as haemosporidians. There is a lack of studies regarding the order Haemosporida in Procellariiformes, and, to date, only the genus Plasmodium has been reported. This survey investigated the occurrence of the three genera of haemosporidians, Plasmodium, Haemoproteus, and Leucocytozoon, in samples collected between 2013 and 2022 from 95 individuals of 14 species of Procellariiformes from southern Brazil, including live animals in rehabilitation centers, individuals caught as incidental bycatch, and carcasses found along the coast. A total of 171 samples of blood and fragments of liver and spleen were analyzed, with extracted DNA being subjected to a nested PCR followed by phylogeny analysis. All animals were negative for Plasmodium spp. and Leucocytozoon spp., but one Black-browed Albatross (Thalassarche melanophris) and one Manx Shearwater (Puffinus puffinus) specimen were positive for Haemoproteus spp. The sequences obtained from positive seabirds did not show 100% similarity with other known lineages available in the MalAvi database and thus were probably novel lineages. However, one sequence clustered together with Haemoproteus noctuae, a parasite from Strigiformes, while the other was grouped with Haemoproteus columbae, which is classically related to Columbiformes. These results suggest that both positive animals may have become infected when beached or in rehabilitation centers by a spillover of vectors from local birds. This highlights the importance of surveillance of the health of Procellariiformes regarding the possibility of dissemination of new pathogens in different bird populations.

Epidemiology of visceral leishmaniasis in municipalities of Mato Grosso and the performance of surveillance activities: an updated investigation

Visceral leishmaniasis (VL) is considered a globally neglected disease. To address the problem of VL endemic to Brazil, the Visceral Leishmaniasis Control Program (VLCP) was created, which recommends the development of health surveillance actions such as the identification of human and canine cases, vector control and prevention of disease. We aimed to investigate the epidemiological situation of VL in municipalities of the State of Mato Grosso (MT) and assess the execution of VLCP activities. Data on human cases were obtained from the Information System for Notifiable Diseases (SINAN), and data from entomological and canine inquiry were provided by the State's Health Department. Analyzes from the period 2019 - 2021 recorded 30 cases of human VL, distributed among 16 municipalities. Vectors were identified in 50% of the municipalities where entomological investigations were carried out, and the predominant specie was Lutzomyia longipalpis. A total of 15,585 dogs were subjected to serological examination, of which 18.91% tested seropositive for Leishmania infantum. However, it must be emphasized that only three municipalities conducted consecutive inquiries involving canine VL. Although VL is distributed widely throughout the State, only a few municipalities have undertaken the actions of the VLCP, thus highlighting the neglected status of the disease.

Genome-Wide Classification of Myb Domain-Containing Protein Families in Entamoeba invadens

Entamoeba histolytica, the causative agent of amebiasis, is the third leading cause of death among parasitic diseases globally. Its life cycle includes encystation, which has been mostly studied in Entamoeba invadens, responsible for reptilian amebiasis. However, the molecular mechanisms underlying this process are not fully understood. Therefore, we focused on the identification and characterization of Myb proteins, which regulate the expression of encystation-related genes in various protozoan parasites. Through bioinformatic analysis, we identified 48 genes in E. invadens encoding MYB-domain-containing proteins. These were classified into single-repeat 1R (20), 2R-MYB proteins (27), and one 4R-MYB protein. The in-silico analysis suggests that these proteins are multifunctional, participating in transcriptional regulation, chromatin remodeling, telomere maintenance, and splicing. Transcriptomic data analysis revealed expression signatures of eimyb genes, suggesting a potential orchestration in the regulation of early and late encystation-excystation genes. Furthermore, we identified probable target genes associated with reproduction, the meiotic cell cycle, ubiquitin-dependent protein catabolism, and endosomal transport. In conclusion, our findings suggest that E. invadens Myb proteins regulate stage-specific proteins and a wide array of cellular processes. This study provides a foundation for further exploration of the molecular mechanisms governing encystation and unveils potential targets for therapeutic intervention in amebiasis.

Biomechanics of parasite migration within hosts

The dissemination of protozoan and metazoan parasites through host tissues is hindered by cellular barriers, dense extracellular matrices, and fluid forces in the bloodstream. To overcome these diverse biophysical impediments, parasites implement versatile migratory strategies. Parasite-exerted mechanical forces and upregulation of the host's cellular contractile machinery are the motors for these strategies, and these are comparably better characterized for protozoa than for helminths. Using the examples of the protozoans, Toxoplasma gondii and Plasmodium, and the metazoan, Schistosoma mansoni, we highlight how quantitative tools such as traction force and reflection interference contrast microscopies have improved our understanding of how parasites alter host mechanobiology to promote their migration.

Severe lophomoniasis in a patient with diabetes and past history of COVID-19 in Central Iran: case report

In this case report, we address the diagnostic challenges and clinical implications of severe infection with Lophomonas blattarum in a patient initially suspected of experiencing long COVID symptoms. We describe the patient's medical history, initial symptoms, diagnostic tests, and treatment. A female patient with diabetes in her early 60s presented with severe shortness of breath and was initially diagnosed with diabetic ketoacidosis (DKA). After resolution of her DKA symptoms, persistent respiratory issues led to a COVID-19 test, which was negative. A chest computed tomography scan revealed abnormalities, prompting bronchoscopy and bronchoalveolar lavage fluid analysis, which confirmed the presence of L. blattarum. Notably, the protozoan remained mobile and viable even after a 4-day transport at ambient temperature. This case emphasizes the importance of considering alternative diagnoses and improving awareness about L. blattarum infection in patients with respiratory symptoms, for timely and accurate management.

Leishmania PNUTS discriminates between PP1 catalytic subunits through an RVxF-ΦΦ-F motif and polymorphisms in the PP1 C-tail and catalytic domain

Phosphoprotein phosphatase 1 (PP1) associates with specific regulatory subunits to achieve, among other functions, substrate selectivity. Among the eight PP1 isotypes in Leishmania, PP1-8e associates with the regulatory protein PNUTS along with the structural factors JBP3 and Wdr82 in the PJW/PP1 complex that modulates RNA polymerase II (pol II) phosphorylation and transcription termination. Little is known regarding interactions involved in PJW/PP1 complex formation, including how PP1-8e is the selective isotype associated with PNUTS. Here, we show that PNUTS uses an established RVxF-ΦΦ-F motif to bind the PP1 catalytic domain with similar interfacial interactions as mammalian PP1-PNUTS and noncanonical motifs. These atypical interactions involve residues within the PP1-8e catalytic domain and N and C terminus for isoform-specific regulator binding. This work advances our understanding of PP1 isoform selectivity and reveals key roles of PP1 residues in regulator binding. We also explore the role of PNUTS as a scaffold protein for the complex by identifying the C-terminal region involved in binding JBP3 and Wdr82 and impact of PNUTS on the stability of complex components and function in pol II transcription in vivo. Taken together, these studies provide a potential mechanism where multiple motifs within PNUTS are used combinatorially to tune binding affinity to PP1, and the C terminus for JBP3 and Wdr82 association, in the Leishmania PJW/PP1 complex. Overall, our data provide insights in the formation of the PJW/PP1 complex involved in regulating pol II transcription in divergent protozoans where little is understood.

Phospholipases A and Lysophospholipases in protozoan parasites

Phospholipases (PLs) and Lysophospholipases (LysoPLs) are a diverse group of esterases responsible for phospholipid or lysophospholipid hydrolysis. They are involved in several biological processes, including lipid catabolism, modulation of the immune response and membrane maintenance. PLs are classified depending on their site of hydrolysis as PLA1, PLA2, PLC and PLD. In many pathogenic microorganisms, from bacteria to fungi, PLAs and LysoPLs have been described as critical virulence and/or pathogenicity factors. In protozoan parasites, a group containing major human and animal pathogens, growing literature show that PLAs and LysoPLs are also involved in the host infection. Their ubiquitous presence and role in host-pathogen interactions make them particularly interesting to study. In this review, we summarize the literature on PLAs and LysoPLs in several protozoan parasites of medical relevance, and discuss the growing interest for them as potential drug and vaccine targets.

The Parasites of Cats in Türkiye

Cats have an important and different place due to their close relationships with humans. Since most of the parasites they carry are zoonotic, it is important to detect them. According to the research, Dipylidium caninum, Joyeuxiella pasqualei, Toxocara spp., Toxascaris leonina, Giardia spp., Isospora spp., and Toxoplasma sp. were found to be higher in cats compared to other parasites. It has been determined that scabies and flea infestations are common as ectoparasites. This review aims to present the reported parasites and their prevalence rates in cats in Türkiye.

Giardia duodenalis (Styles, 1902) in Cattle: Isolation of Calves with Diarrhoea and Manure Treatment in the Lagoon Presented as Risk Factors in Latvian Herds

Giardia duodenalis is a waterborne zoonotic protozoan that causes gastrointestinal tract inflammation in humans, cattle, and other animals. The aim of the present study was to estimate the prevalence and potential risk factors for Giardia infection in cattle in Latvia. During 2020-2021, a total of 973 individual faecal samples from cattle aged from 1 day to 12 years old, from 32 cattle herds, were tested for Giardia cyst presence with immunofluorescence staining followed by Giardia assemblage differentiation targeting beta-giardin gene. Using a questionnaire, information was collected to estimate the potential risk factors for G. duodenalis infection in cattle herds. Giardia was found in 8.4% of the examined cattle with a mean intensity of 5756 cysts per gram of faeces. The highest prevalence was observed in the 0 to 3-month-old calves (16.4%). At least one Giardia shedding animal was found in 27 herds with an overall prevalence of 84.4%. Significantly higher prevalence was found for cattle infected with G. duodenalis assemblage E compared to that infected with assemblage A: 88.7% and 11.3%, respectively. Protective factors such as age and rodent control and change of shoes were found to be significant for Giardia infection, while isolating calves for diarrhoea and water bodies (ponds/lakes) in pasture were potential risk factors in Latvian cattle.

Babesia gibsoni Whole-Genome Sequencing, Assembling, Annotation, and Comparative Analysis

The intracellular protozoan parasite Babesia gibsoni infects canine erythrocytes and causes babesiosis. The hazards to animal health have increased due to the rise of B. gibsoni infections and medication resistance. However, the lack of high-quality full-genome sequencing sets has expanded the obstacles to the development of pathogeneses, drugs, and vaccines. In this study, the whole genome of B. gibsoni was sequenced, assembled, and annotated. The genomic size of B. gibsoni was 7.94 Mbp in total. Four chromosomes with the size of 0.69 Mb, 2.10 Mb, 2.77 Mb, and 2.38 Mb, respectively, 1 apicoplast (28.4 Kb), and 1 mitochondrion (5.9 Kb) were confirmed. KEGG analysis revealed 2,641 putative proteins enriched on 316 pathways, and GO analysis showed 7,571 annotations of the nuclear genome in total. Synteny analysis showed a high correlation between B. gibsoni and B. bovis. A new divergent point of B. gibsoni occurred around 297.7 million years ago, which was earlier than that of B. bovis, B. ovata, and B. bigemina. Orthology analysis revealed 22 and 32 unique genes compared to several Babesia spp. and apicomplexan species. The metabolic pathways of B.gibsoni were characterized, pointing to a minimal size of the genome. A species-specific secretory protein SA1 and 19 homologous genes were identified. Selected specific proteins, including apetala 2 (AP2) factor, invasion-related proteins BgAMA-1 and BgRON2, and rhoptry function proteins BgWH_04g00700 were predicted, visualized, and modeled. Overall, whole-genome sequencing provided molecular-level support for the diagnosis, prevention, clinical treatment, and further research of B. gibsoni. IMPORTANCE The whole genome of B. gibsoni was first sequenced, annotated, and disclosed. The key part of genome composition, four chromosomes, was comparatively analyzed for the first time. A full-scale phylogeny evolution analysis based on the whole-genome-wide data of B. gibsoni was performed, and a new divergent point on the evolutionary path was revealed. In previous reports, molecular studies were often limited by incomplete genomic data, especially in key areas like life cycle regulation, metabolism, and host-pathogen interaction. With the whole-genome sequencing of B. gibsoni, we provide useful genetic data to encourage the exploration of new terrain and make it feasible to resolve the theoretical and practical problems of babesiosis.

Prevalence of gastrointestinal parasites in domestic cats (Felis catus) diagnosed by different coproparasitological techniques in the municipality of Seropédica, Rio de Janeiro

The objectives of this work were to investigate the occurrence of parasites in feces of cats, compare different coproparasitological techniques for their diagnosis and determine associations with parasitism. The samples were processed using three different coproparasitological techniques: centrifugal flotation in sucrose, centrifugal flotation in ZnSO4 and simple sedimentation. The parasitic association between parasitism and variables such as age, sex and fecal consistency was performed using the chi-square test or the G test with a significance level of 5%. A total of 237 samples were analyzed, of which 93 (39.2%) were positive, being Ancylostoma spp. (17.3%), Giardia intestinalis (12.2%), Platynosomum illiciens (8.0%), Cystoisospora spp. (6.3%), Toxoplasma gondii/ Hammondia hammondi (3.4%), Diphyllobothriidae (2.1%), Toxocara spp. (1.7%), Dipylidium caninum (1.3%) and Mesocestoides spp. (0.8%). In the parasitism association analysis, it was possible to verify a statistical difference in the age category for Cystoisospora spp. (p=0.001) observing a strong relationship between parasitism and young animals, the association with sex proved to be important for P. illiciens (p<0.001) with a higher frequency of parasitized females and fecal consistency revealed to be related to the parasites G. intestinalis (p=0.007) and P. illiciens (p=0.033) showing a higher number of positive animals for these parasites with normal fecal consistency. In conclusion, we observed a higher occurrence of Ancylostoma spp. and G. intestinalis in fecal samples from domestic cats received in routine diagnoses and the presence of other parasites with zoonotic potential, as well as the relationship of these diagnosed parasites with the categories sex, age and fecal consistency.

Primary pulmonary amoebiasis mimicking lung tumour in immunocompromised patient: A case report

Amoebiasis is the most common protozoan disease caused by Entamoeba histolytica. The second most frequent extraintestinal infection, behind amoebic liver abscess, is pulmonary amoebiasis. We present the case of an immunocompromised 40-year-old man. He complained of cough for 1 month, shortness of breath, and fever. Chest x-ray demonstrated left paracardial consolidation, possibly pneumonia or a mass. Chest CT scans with contrast revealed the presence of an abscess-mimicking tumour. CT-guided TTB and histology examinations indicated the presence of trophozoites of E. histolytica. This patient was diagnosed with pulmonary amoebiasis. Diagnostic criteria for pulmonary amoebiasis include clinical manifestations, radiography, and microscopic examination. There was an improvement in clinical response after a 10-day course of antibiotics. Amoebiasis of the lungs is treatable with medicines and drainage when necessary. Early diagnosis and treatment are imperative to decrease mortality and morbidity.

Causes of fetal death in the Flemish cattle herd in Brazil

Background and Aim

Flemish cattle in Brazil are on the brink of extinction and are found only in one herd in Lages, Santa Catarina State. This study aimed to uncover the reasons for the recurring abortions in the Flemish cattle herd.

Materials and Methods

Seventeen Flemish fetuses underwent postmortem examinations, with samples collected for histopathology and microbiology culture tests, polymerase chain reaction (PCR) test for Neospora caninum, and reverse transcription-PCR (RT-PCR) test for bovine viral diarrhea virus (BVDV) from 2015 to 2020.

Results

Of the 17 fetuses, N. caninum was the most common diagnosis and was found in 88% (15/17). One fetus (5.8%) had a coinfection with N. caninum and Citrobacter amalonaticus, leading to fibrinonecrotic pericarditis. All fetuses tested negative for BVDV by RT-PCR. Of the 107 dams tested by indirect immunofluorescence assay, 26 (25.2%) were anti-N. caninum seropositive, with 17 (65.4%) aborting and 5 (19.2%) having estrus repetition. Reverse transcription-PCR results showed that 9 (8.4%) of the serum samples collected from dams tested positive, which tested follow-up test 3 months later, indicating a BVDV transient infection. The factors that contributed to neosporosis included dogs' access to pastures and improper disposal of fetal remains, which made it easier for dogs to consume them.

Conclusion

This study warns the occurrence of N. caninum as a cause of reproductive disorders that can lead to abortion in the studied Flemish cattle herd.

Pre-exposure to Fe2O3 or TiO2 Nanoparticles Inhibits Subsequent Biological Uptake of 55Fe-Labeled Fe2O3 Nanoparticles

Aquatic organisms are frequently exposed to various nanoparticles (NPs) in the natural environment. Thus, studies of NP bioaccumulation should include organisms that have been previously exposed to NPs. Our study investigated the effects of pre-exposure of Tetrahymena thermophila (T. thermophila) to Fe₂O₃ or TiO₂ NPs on the protozoan's subsequent uptake of ⁵⁵Fe-labeled Fe₂O₃ (⁵⁵Fe₂O₃) NPs. Molecular mechanisms underlying the pre-exposure effects were explored in transcriptomic and metabolomic experiments. Pre-exposure to either NPs inhibited the subsequent uptake of ⁵⁵Fe₂O₃ NPs. The results of the transcriptomic experiment indicated that NP pre-exposure influenced the expression of genes related to phagosomes and lysosomes and physiological processes such as glutathione and lipid metabolism, which are closely associated with the endocytosis of ⁵⁵Fe₂O₃ NPs. The differentially expressed metabolites obtained from the metabolomic experiments showed an enrichment of energy metabolism and antioxidation pathways in T. thermophila pre-exposed to NPs. Together, these results demonstrate that the pre-exposure of T. thermophila to Fe₂O₃ or TiO₂ NPs inhibited the protozoan's subsequent uptake of ⁵⁵Fe₂O₃ NPs, possibly by mechanisms involving the alteration of endocytosis-related organelles, the induction of oxidative stress, and a lowering of the intracellular energy supply. Thus, NP pre-exposure represents a scenario which can inform increasingly realistic estimates of NP bioaccumulation.

Integrated Approach for Synthetic Cathinone Drug Prioritization and Risk Assessment: In Silico Approach and Sub-Chronic Studies in Daphnia magna and Tetrahymena thermophila

Synthetic cathinones (SC) are drugs of abuse that have been reported in wastewaters and rivers raising concern about potential hazards to non-target organisms. In this work, 44 SC were selected for in silico studies, and a group of five emerging SC was prioritized for further in vivo ecotoxicity studies: buphedrone (BPD), 3,4-dimethylmethcathinone (3,4-DMMC), butylone (BTL), 3-methylmethcathinone (3-MMC), and 3,4-methylenedioxypyrovalerone (MDPV). In vivo short-term exposures were performed with the protozoan Tetrahymena thermophila (28 h growth inhibition assay) and the microcrustacean Daphnia magna by checking different indicators of toxicity across life stage (8 days sublethal assay at 10.00 µg L^-1). The in silico approaches predicted a higher toxic potential of MDPV and lower toxicity of BTL to the model organisms (green algae, protozoan, daphnia, and fish), regarding the selected SC for the in vivo experiments. The in vivo assays showed protozoan growth inhibition with MDPV > BPD > 3,4-DMMC, whereas no effects were observed for BTL and stimulation of growth was observed for 3-MMC. For daphnia, the responses were dependent on the substance and life stage. Briefly, all five SC interfered with the morphophysiological parameters of juveniles and/or adults. Changes in swimming behavior were observed for BPD and 3,4-DMMC, and reproductive parameters were affected by MDPV. Oxidative stress and changes in enzymatic activities were noted except for 3-MMC. Overall, the in silico data agreed with the in vivo protozoan experiments except for 3-MMC, whereas daphnia in vivo experiments showed that at sublethal concentrations, all selected SC interfered with different endpoints. This study shows the importance to assess SC ecotoxicity as it can distress aquatic species and interfere with food web ecology and ecosystem balance.

Corrigendum: The sole DNA ligase in Entamoeba histolytica is a high-fidelity DNA ligase involved in DNA damage repair

[This corrects the article DOI: 10.3389/fcimb.2018.00214.].

Protozoa-Derived Extracellular Vesicles on Intercellular Communication with Special Emphasis on Giardia lamblia

Parasitic diseases are an important worldwide problem threatening human health and affect millions of people. Acute diarrhea, intestinal bleeding, malabsorption of nutrients and nutritional deficiency are some of the issues related to intestinal parasitic infections. Parasites are experts in subvert the host immune system through different kinds of mechanisms. There are evidences that extracellular vesicles (EVs) have an important role in dissemination of the disease and in modulating the host immune system. Released by almost all types of cells, these nanovesicles are a natural secretory product containing multiple components of interest. The EVs are classified as apoptotic bodies, microvesicles, exosomes, ectosomes, and microparticles, according to their physical characteristics, biochemical composition and cell of origin. Interestingly, EVs play an important role in intercellular communication between parasites as well as with the host cells. Concerning Giardia lamblia, it is known that this parasite release EVs during it life cycle that modulate the parasite growth and adherence as well the immune system of the host. Here we review the recently updates on protozoa EVs, with particular emphasis on the role of EVs released by the flagellate protozoa G. lamblia in cellular communication and its potential for future applications as vaccine, therapeutic agent, drug delivery system and as diagnostic or prognostic biomarker.

Microcephaly and hydrocephalus in a sheep fetus infected with Neospora caninum in Southern Brazil - Short communication

A case of non-communicating hydrocephalus and microcephaly in a sheep fetus infected with Neospora caninum from Lages, Santa Catarina, Brazil, is reported. Macroscopically, there was moderate flattening and narrowing of the skull, and the portion of the cerebral hemispheres was markedly reduced in size, measuring 3.5 × 3.5 × 0.5 cm, with marked diffuse flattening of the brain gyri and dilation of the lateral ventricles. Cerebrospinal fluid samples were positive to N. caninum detection by PCR. Histologically, there was discrete focal lymphoplasmacytic necrotising encephalitis on the floor of the lateral ventricle, discrete multifocal gliosis and discrete multifocal lymphoplasmacytic myositis. Through the molecular detection of N. caninum in the cerebrospinal fluid, it was possible to report what appears to be the first case of non-communicating hydrocephalus and microcephaly in an ovine fetus infected with N. caninum.

Characterization of a highly diverged mitochondrial ATP synthase Fo subunit in Trypanosoma brucei

The mitochondrial F₁F_o ATP synthase of the parasite Trypanosoma brucei has been previously studied in detail. This unusual enzyme switches direction in functionality during the life cycle of the parasite, acting as an ATP synthase in the insect stages, and as an ATPase to generate mitochondrial membrane potential in the mammalian bloodstream stages. Whereas the trypanosome F₁ moiety is relatively highly conserved in structure and composition, the F_o subcomplex and the peripheral stalk have been shown to be more variable. Interestingly, a core subunit of the latter, the normally conserved subunit b, has been resistant to identification by sequence alignment or biochemical methods. Here, we identified a 17 kDa mitochondrial protein of the inner membrane, Tb927.8.3070, that is essential for normal growth, efficient oxidative phosphorylation, and membrane potential maintenance. Pull-down experiments and native PAGE analysis indicated that the protein is both associated with the F₁F_o ATP synthase and integral to its assembly. In addition, its knockdown reduced the levels of F_o subunits, but not those of F₁, and disturbed the cell cycle. Finally, analysis of structural homology using the HHpred algorithm showed that this protein has structural similarities to F_o subunit b of other species, indicating that this subunit may be a highly diverged form of the elusive subunit b.

Effects of municipal wastewater treatment plant effluent quality on aquatic ecosystem organisms

The management and quality monitoring of wastewater have an important role in sustainable development. A recent approach in environmental protection involves the ecotoxicological assessment of effluents to complement the usual chemical evaluations. This study assessed the impacts of wastewater treatment plant (WWTP) effluent quality in a location in Western Cape province, South Africa using organisms that bear different ecosystem-level function responsibilities like the Pseudokirchneriella subcapitata (microalgae), Daphnia magna (crustaceans), and Tetrahymena thermophila (protozoan) in addition to the physicochemical parameters. The effluent showed values of chemical oxygen demand (COD; 41-83 mg L^-1), dissolved oxygen (DO; 2.7-3.1 mg L^-1), Redox potential (189-265 mV), and total dissolved solids (TDS; 656-718 ppm). The protozoan Tetrahymena thermophila ecotoxicity test exhibited toxic effects of the effluents within 24-h with a mean lethal value (LC₅₀) of 1.12% for the winter season. The findings of this study revealed that analyzed physicochemical parameters are within the regulatory water quality acceptable standard thresholds with few exceptions, while the biotests were able to determine the toxicity levels and sensitivities of each test. The results showed that the WWTP whole effluent exerted toxicity to test organisms, but dilution can mitigate the effects considerably. The use of ecotoxicological assessment methods for municipal WWTP effluent may enhance existing water management strategies.

Automated Diagnostics: Advances in the Diagnosis of Intestinal Parasitic Infections in Humans and Animals

The increasingly close proximity between people and animals is of great concern for public health, given the risk of exposure to infectious diseases transmitted through animals, which are carriers of more than 60 zoonotic agents. These diseases, which are included in the list of Neglected Tropical Diseases, cause losses in countries with tropical and subtropical climates, and in regions with temperate climates. Indeed, they affect more than a billion people around the world, a large proportion of which are infected by one or more parasitic helminths, causing annual losses of billions of dollars. Several studies are being conducted in search for differentiated, more sensitive diagnostics with fewer errors. These studies, which involve the automated examination of intestinal parasites, still face challenges that must be overcome in order to ensure the proper identification of parasites. This includes a protocol that allows for elimination of most of the debris in samples, satisfactory staining of parasite structures, and a robust image database. Our objective here is therefore to offer a critical description of the techniques currently in use for the automated diagnosis of intestinal parasites in fecal samples, as well as advances in these techniques.

Bhalin, an Essential Cytoskeleton-Associated Protein of Trypanosoma brucei Linking TbBILBO1 of the Flagellar Pocket Collar with the Hook Complex

Background: In most trypanosomes, endo and exocytosis only occur at a unique organelle called the flagellar pocket (FP) and the flagellum exits the cell via the FP. Investigations of essential cytoskeleton-associated structures located at this site have revealed a number of essential proteins. The protein TbBILBO1 is located at the neck of the FP in a structure called the flagellar pocket collar (FPC) and is essential for biogenesis of the FPC and parasite survival. TbMORN1 is a protein that is present on a closely linked structure called the hook complex (HC) and is located anterior to and overlapping the collar. TbMORN1 is essential in the bloodstream form of T. brucei. We now describe the location and function of BHALIN, an essential, new FPC-HC protein. Methodology/Principal Findings: Here, we show that a newly characterised protein, BHALIN (BILBO1 Hook Associated LINker protein), is localised to both the FPC and HC and has a TbBILBO1 binding domain, which was confirmed in vitro. Knockdown of BHALIN by RNAi in the bloodstream form parasites led to cell death, indicating an essential role in cell viability. Conclusions/Significance: Our results demonstrate the essential role of a newly characterised hook complex protein, BHALIN, that influences flagellar pocket organisation and function in bloodstream form T. brucei parasites.

Cyclosporiasis-Updates on Clinical Presentation, Pathology, Clinical Diagnosis, and Treatment

Cyclospora cayetanensis is an intestinal coccidian parasite transmitted to humans through the consumption of oocysts in fecally contaminated food and water. Infection is found worldwide and is highly endemic in tropical and subtropical regions with poor sanitation. Disease in developed countries is usually observed in travelers and in seasonal outbreaks associated with imported produce from endemic areas. Recently, summertime outbreaks in the United States have also been linked to locally grown produce. Cyclosporiasis causes a diarrheal illness which may be severe in infants, the elderly, and immunocompromised individuals. The increased adoption of highly sensitive molecular diagnostic tests, including commercially available multiplex panels for gastrointestinal pathogens, has facilitated the detection of infection and likely contributed to the increased reports of cases in developed countries. This manuscript reviews important aspects of the biology, epidemiology, and clinical manifestations of C. cayetanensis and provides an in-depth discussion of current laboratory diagnostic methods.

Epidemiological study of toxoplasmosis outbreaks in Brazil

In Brazil, notification of toxoplasmosis outbreaks and epidemiological investigation is a mandatory activity of health surveillance. We investigated the risk factors for toxoplasmosis during outbreaks, notifications of outbreaks by the health secretary and reports in the literature. Other factors related to the municipalities were determined through the Institute of Geography and Statistics portal. We found that fruits and vegetables were the most described transmission routes in outbreaks, and oocysts were the most common parasitic form; in recent years; there has been an increase in outbreak notifications. We also found that municipalities with high municipal human development index have a higher number of toxoplasmosis infections during outbreaks. There is a need to raise awareness among the population and producers regarding good water management and quality practices and to facilitate the acquisition of complex data to improve preventive strategies.

Parasite-Mediated Remodeling of the Host Microfilament Cytoskeleton Enables Rapid Egress of Trypanosoma cruzi following Membrane Rupture

Chagas’ disease arises as a direct consequence of the lytic cycle of Trypanosoma cruzi in the mammalian host. While invasion is well studied for this pathogen, study of egress has been largely neglected. Here, we provide the first description of T. cruzi egress documenting a coordinated mechanism by which T. cruzi engineers its escape from host cells in which it has proliferated and which is essential for maintenance of infection and pathogenesis. Our results indicate that this parasite egress is a sudden event involving coordinated remodeling of host cell cytoskeleton and subsequent rupture of host cell plasma membrane. We document that host cells maintain plasma membrane integrity until immediately prior to parasite release and report the sequential transformation of the host cell’s actin cytoskeleton from normal meshwork in noninfected cells to spheroidal cages—a process initiated shortly after amastigogenesis. Quantification revealed gradual reduction in F-actin over the course of infection, and using cytoskeletal preparations and electron microscopy, we were able to observe disruption of the F-actin proximal to intracellular trypomastigotes. Finally, Western blotting experiments suggest actin degradation driven by parasite proteases, suggesting that degradation of cytoskeleton is a principal component controlling the initiation of egress. Our results provide the first description of the cellular mechanism that regulates the lytic component of the T. cruzi lytic cycle. We show graphically how it is possible to preserve the envelope of host cell plasma membrane during intracellular proliferation of the parasite and how, in cells packed with amastigotes, differentiation into trypomastigotes may trigger sudden egress.

Stages of Granulomatous Response Against Histozoic Metazoan Parasites in Mullets (Osteichthyes: Mugilidae)

Simple Summary

Parasitic diseases represent a common issue in fish and, when histozoic forms are present, this elicits a chronic inflammatory reaction leading to granuloma formation. Despite the large knowledge of granuloma formation due to parasites in visceral organs, little is known about the development and the evolutive stages of granulomas in naturally infected fish. Mullets (Osteichthyes: Mugilidae) are a widespread euryhaline fish species that harbor different parasites, thus representing a suitable model for the study of parasite-induced granulomas. Combining histopathology and immunohistochemical tools, we identified three developmental granuloma stages (pre-granuloma, intermediate, and late stage), that ranged from an intact parasite with mild signs of tissue reaction to the formation of a structured granuloma. The identified histological patterns could be reliable tools in the staging of the granulomatous response associated with histozoic parasites and are an attempt to broaden the knowledge of the inflammatory response in different host–parasite systems.

Abstract

Histozoic parasite–fish host interaction is a dynamic process that leads to the formation of a granuloma, a specific chronic inflammatory response with discernible histological features. Mullets (Osteichthyes: Mugilidae) represent a suitable model concerning the development of such lesions in the host–parasite interface. The present work aimed to identify granuloma developmental stages from the early to the late phase of the infection and to characterize the immune cells and non-inflammatory components of the granuloma in different stages. For this purpose, 239 mullets were collected from 4 Sardinian lagoons, and several organs were examined by combining histopathological, bacteriological, and immunohistochemical methods. Granulomas associated with trematode metacercariae and myxozoan parasites were classified into three developmental stages: (1) pre-granuloma stage, characterized by intact encysted parasite and with no or mild tissue reaction; (2) intermediate stage, with partially degenerated parasites, necrosis, and a moderate number of epithelioid cells (ECs); and (3) late stage, with a necrotic core and no detectable parasite with a high number of ECs and fibroblasts. The three-tier staging and the proposed morphological diagnosis make it conceivable that histopathology could be an essential tool to evaluate the granulomas associated with histozoic parasitic infection in fish.

Intracellular Hybrid Biosystem in a Protozoan to Trigger Visible-Light-Driven Photocatalysis

Incorporating artificial photosensitizers with microorganisms has recently been recognized as an effective way to convert light energy into chemical energy. However, the incorporated biosystem is usually constructed in an extracellular manner and is vulnerable to the external environment. Here, we develop an intracellular hybrid biosystem in a higher organism protozoa Tetrahymena pyriformis, in which the in vivo synthesized CdS nanoparticles trigger photoreduction of nitrobenzene into aniline under visible-light irradiation. Integrating a photosensitizer CdS into T. pyriformis enables the photosensitizer CdS, inherent nitroreductase, and the cytoplasmic reductive substance in T. pyriformis to synergistically engage in the photocatalysis process, generating a greatly enhanced aniline yield with a 40-fold increment. Moreover, building an intracellular hybrid biosystem in mutant T. pyriformis could even grant it new capability of reducing nitrobenzene into aniline under visible-light irradiation. Such an intracellular hybrid biosystem paves a new way to functionalize higher organisms and diversify light energy conversion.

Toxoplasma TgATG9 is critical for autophagy and long-term persistence in tissue cysts

Many of the world's warm-blooded species are chronically infected with Toxoplasma gondii tissue cysts, including an estimated one-third of the global human population. The cellular processes that permit long-term persistence within the cyst are largely unknown for T. gondii and related coccidian parasites that impact human and animal health. Herein, we show that genetic ablation of TgATG9 substantially reduces canonical autophagy and compromises bradyzoite viability. Transmission electron microscopy revealed numerous structural abnormalities occurring in ∆atg9 bradyzoites. Intriguingly, abnormal mitochondrial networks were observed in TgATG9-deficient bradyzoites, some of which contained numerous different cytoplasmic components and organelles. ∆atg9 bradyzoite fitness was drastically compromised in vitro and in mice, with very few brain cysts identified in mice 5 weeks post-infection. Taken together, our data suggests that TgATG9, and by extension autophagy, is critical for cellular homeostasis in bradyzoites and is necessary for long-term persistence within the cyst of this coccidian parasite.

Comparison between five coprological methods for the diagnosis of Balantidium coli cysts in fecal samples from pigs

Background and Aim:

Balantidium coli is a protozoan that can infect humans and non-human primates, being the domestic pigs the animals most affected by this parasite. This study aimed to compare the performance of five coprological methods for diagnosis of Balantidium coli cysts in fecal samples from pigs.

Materials and Methods:

From September to December 2019, 558 fecal samples were collected from the rectum of backyard pigs in the Bucaramanga metropolitan area, Colombia. The average age of the sampled animals was 3-4 months. Fecal samples collected were tested using the following coprological techniques: Direct examination with Lugol’s iodine solution, buffered saline, centrifugation/flotation and McMaster techniques, and Ziehl–Neelsen method.

Results:

The results indicate that B. coli cysts were diagnosed most frequently through direct examination with Lugol’s iodine solution (52.7% of the samples) followed by direct examination with a buffered saline solution (37.6%). Moderate concordance (k=0.41; p<0.05) was determined between direct method with Lugol’s iodine and buffered saline solution, McMaster and buffered saline (k=0.35; p<0.05), and centrifugation/flotation and buffered saline (k=0.28; p<0.05) showed a fair degree of concordance. The rest of the comparisons were classified as poor. The flotation techniques (centrifugation/flotation and McMaster) did not show good recovery of cysts.

Conclusion:

It is concluded that the most efficient method for diagnosing this parasitosis was to an association between direct examination with Lugol’s iodine solution and buffered saline.

CRISPR/Cas9 Ribonucleoprotein-Based Genome Editing Methodology in the Marine Protozoan Parasite Perkinsus marinus

Perkinsus marinus (Perkinsozoa), a close relative of apicomplexans, is an osmotrophic facultative intracellular marine protozoan parasite responsible for "Dermo" disease in oysters and clams. Although there is no clinical evidence of this parasite infecting humans, HLA-DR40 transgenic mice studies strongly suggest the parasite as a natural adjuvant in oral vaccines. P. marinus is being developed as a heterologous gene expression platform for pathogens of medical and veterinary relevance and a novel platform for delivering vaccines. We previously reported the transient expression of two rodent malaria genes Plasmodium berghei HAP2 and MSP8. In this study, we optimized the original electroporation-based protocol to establish a stable heterologous expression method. Using 20 μg of pPmMOE[MOE1]:GFP and 25.0 × 106 P. marinus cells resulted in 98% GFP-positive cells. Furthermore, using the optimized protocol, we report for the first time the successful knock-in of GFP at the C-terminus of the PmMOE1 using ribonucleoprotein (RNP)-based CRISPR/Cas9 gene editing methodology. The GFP was expressed 18 h post-transfection, and expression was observed for 8 months post-transfection, making it a robust and stable knock-in system.

A study on intestinal parasitic infections among school children in Karaikal

Introduction

Intestinal parasitic infections (IPIs) play a major role in global disease burden with significant morbidity. The most vulnerable age group was school going children and is transmitted through soil. About 90% of infected individuals remain asymptomatic. The present study was designed to screen for IPI among school children in Karaikal, to identify the asymptomatic infections and to assess the type and occurrence of IPIs.

Methodology

A cross-sectional study was carried out from July to September 2018 among school children in the age group of 6-14 years after getting ethical clearance. A total of 335 single stool samples were collected. The samples were subjected to macroscopic examination, microscopic examination and subjected to concentration techniques such as salt floatation and formal ether sedimentation technique. Two separate fresh stool smears were made on the microscopic slides for trichrome and modified acid-fast staining. The results were calculated as percentage, frequency/proportion, and Chi-square test using IBM SPSS software version 19.

Results

Only 90 (28%) out of 324 stool samples were positive for the presence of intestinal parasites. The sensitivity of formal ether sedimentation technique (58%) was higher than other techniques. None of the ova of helminths detected. Modified acid-fast staining was negative for coccidian parasites.

Conclusions

The low prevalence of protozoan parasites and total absence of helminths in the study revealed the effective role of nationwide deworming program and Swachh Bharat Abhiyan program. However, anthelminthic does not cover the protozoan parasites and it exists among asymptomatic healthy population.

Giardia and Cryptosporidium in Neo-Tropical Rodents and Marsupials: Is There Any Zoonotic Potential?

Cryptosporidiosis and giardiasis have been identified as emerging diseases in both developed and developing countries. Wildlife has been highlighted to play a major role in the spread of these diseases to humans. This review aims to highlight the research findings that relate to Cryptosporidium spp. and Giardia spp., with a focus on (1) parasitism of neo-tropical hystricomorphic rodents and marsupials from the genus Didelphis and (2) prevention and treatment strategies for humans and animals for the neo-tropical region. It was found that there are few studies conducted on neo-tropical rodent and marsupial species, but studies that were found illustrated the potential role these animals may play as zoonotic carriers of these two parasites for the neo-tropical region. Thus, it is recommended that further studies be done to assess the threat of protozoan parasites in neo-tropical wildlife to humans and domestic animals, and to further determine the most effective prophylaxis adapted for the unique conditions of the region.

Canine leishmaniasis in Northern California-A case report

A 3-year-old dog was referred to the Veterinary Medical Teaching Hospital of the University of California-Davis for further evaluation of episodes of epistaxis of 1-year duration and peripheral lymphadenopathy. The patient had a history of atopic dermatitis with no travel history outside of California. Hyperglobulinemia with a polyclonal gammopathy was noted on serum protein electrophoresis. Microscopic evaluation of a bone marrow aspirate sample revealed many free and intra-cellular amastigotes of Leishmania sp. that was further confirmed by qPCR as L infantum. This is, to the best of our knowledge, the first reported case of canine leishmaniasis in the state of California. The patient is believed to have been vertically infected from the dam who is from Serbia and remained subclinical until presentation. Because the clinical progression of leishmaniasis is variable, it is important that precautions be discussed with owners acquiring puppies with dams from endemic regions of leishmaniasis to prevent zoonotic exposure in states where competent vectors are present.

De Novo Synthesis of Phosphatidylcholine Is Essential for the Promastigote But Not Amastigote Stage in Leishmania major

Phosphatidylcholine (PC) is the most abundant type of phospholipids in eukaryotes constituting ~30% of total lipids in Leishmania. PC synthesis mainly occurs via the choline branch of the Kennedy pathway (choline ⇒ choline-phosphate ⇒ CDP-choline ⇒ PC) and the N-methylation of phosphatidylethanolamine (PE). In addition, Leishmania parasites can acquire PC and other lipids from the host or culture medium. In this study, we assessed the function and essentiality of choline ethanolamine phosphotransferase (CEPT) in Leishmania major which is responsible for the final step of the de novo synthesis of PC and PE. Our data indicate that CEPT is localized in the endoplasmic reticulum and possesses the activity to generate PC from CDP-choline and diacylglycerol. Targeted deletion of CEPT is only possible in the presence of an episomal CEPT gene in the promastigote stage of L. major. These chromosomal null parasites require the episomal expression of CEPT to survive in culture, confirming its essentiality during the promastigote stage. In contrast, during in vivo infection of BALB/c mice, these chromosomal null parasites appeared to lose the episomal copy of CEPT while maintaining normal levels of virulence, replication and cellular PC. Therefore, while the de novo synthesis of PC/PE is indispensable for the proliferation of promastigotes, intracellular amastigotes appear to acquire most of their lipids through salvage and remodeling.

Biochemical and structural characterisation of a protozoan beta-carbonic anhydrase from Trichomonas vaginalis

We report the biochemical and structural characterisation of a beta-carbonic anhydrase (β-CA) from Trichomonas vaginalis, a unicellular parasite responsible for one of the world’s leading sexually transmitted infections, trichomoniasis. CAs are ubiquitous metalloenzymes belonging to eight evolutionarily divergent groups (α, β, γ, δ, ζ, η, θ, and ι); humans express only α-CAs, whereas many clinically significant pathogens express only β- and/or γ-CAs. For this reason, the latter two groups of CAs are promising biomedical targets for novel antiinfective agents. The β-CA from T. vaginalis (TvaCA1) was recombinantly produced and biochemically characterised. The crystal structure was determined, revealing the canonical dimeric fold of β-CAs and the main features of the enzyme active site. The comparison with the active site of human CA enzymes revealed significant differences that can be exploited for the design of inhibitors selective for the protozoan enzyme with respect to the human ones.

Long-Term Determinants of the Seroprevalence of Toxoplasma gondii in a Wild Ungulate Community

Toxoplasma gondii is an obligate intracellular protozoan which infects warm-blooded vertebrates, including humans, worldwide. In the present study, the epidemiology of T. gondii was studied in the wild ungulate host community (wild boar, red deer, and fallow deer) of Doñana National Park (DNP, south-western Spain) for 13 years (2005-2018). We assessed several variables which potentially operate in the medium and long-term (environmental features, population, and stochastic factors). Overall, the wild ungulate host community of DNP had high seroprevalence values of T. gondii (STG; % ± confidence interval (CI) 95%; wild boar (Sus scrofa) 39 ± 3.3, n = 698; red deer (Cervus elaphus) 30.7 ± 4.4, n = 423; fallow deer (Dama dama) 29.7 ± 4.2, n = 452). The complex interplay of hosts and ecological/epidemiological niches, together with the optimal climatic conditions for the survival of oocysts that converge in this area may favor the spread of the parasite in its host community. The temporal evolution of STG oscillated considerably, mostly in deer species. The relationships shown by statistical models indicated that several factors determined species patterns. Concomitance of effects among species, indicated that relevant drivers of risk operated at the community level. Our focus, addressing factors operating at broad temporal scale, allows showing their impacts on the epidemiology of T. gondii and its trends. This approach is key to understanding the epidemiology and ecology to T. gondii infection in wild host communities in a context where the decline in seroprevalence leads to loss of immunity in humans.

Exposure to Toxoplasma gondii Through Consumption of Raw or Undercooked Meat: A Systematic Review and Meta-Analysis

Toxoplasma gondii is a globally distributed protozoan that mainly causes health issues in the fetuses of pregnant women who have never been exposed to this parasite and patients with deficient immune systems. Except in these vulnerable populations, the primary infection generally goes unnoticed in most healthy individuals. Apart from transplant/transfusion, congenital transmission, direct contact with infected cats or their feces, and environmental contamination (i.e., oocysts in food, water, and soil) pathways, humans can acquire the parasite through consumption of animal tissues infected by T. gondii. This meta-analysis estimated the risk of acquiring T. gondii by consuming raw or undercooked meat, regardless of which animal species are eaten. Using a random-effect model, crude and adjusted pooled measures of association (risk and odds ratio) were estimated according to study design (cohort, case-control, and cross-sectional studies). The meta-analysis included measures of heterogeneity as well as quality rating scales for each study design. Our results suggest that individuals who eat raw or undercooked meat have, respectively, 1.2-1.3 times the risk and 1.7-3.0 times the odds of T. gondii infection compared to those who thoroughly cook meat, regardless of the animal species they consume. These results align with the current understanding that adequately cooking meat inactivates the parasite and decreases the risk of transmission. Seroprevalence ranged from 1.3% to 88.6%, while the proportion of individuals eating raw or undercooked meat fluctuated from 0.7% to 98.3% across the studies in the meta-analysis. These numbers reflect various preferences with regard to eating meat (i.e., eating tartar, sausages, or salamis) as well as individual, cultural and religious food habits, and personal awareness.

Characterization of Cystathionine β-Synthase TtCbs1 and Cysteine Synthase TtCsa1 Involved in Cysteine Biosynthesis in Tetrahymena thermophila

Cysteine is implicated in important biological processes. It is synthesized through two different pathways. Cystathionine β-synthase and cystathionine γ-lyase participate in the reverse transsulfuration pathway, while serine acetyltransferase and cysteine synthase function in the de novo pathway. Two evolutionarily related pyridoxal 5'-phosphate-dependent enzymes, cystathionine β-synthase TtCBS1 (TTHERM_00558300) and cysteine synthase TtCSA1 (TTHERM_00239430), were identified from a freshwater protozoan Tetrahymena thermophila. TtCbs1 contained the N-terminal heme binding domain, catalytic domain, and C-terminal regulatory domain, whereas TtCsa1 consisted of two α/β domains. The catalytic core of the two enzymes is similar. TtCBS1 and TtCSA1 showed high expression levels in the vegetative growth stage and decreased during the sexual developmental stage. TtCbs1 and TtCsa1 were localized in the cytoplasm throughout different developmental stages. His-TtCbs1 and His-TtCsa1 were expressed and purified in vitro. TtCbs1 catalyzed the canonical reaction with the highest velocity and possessed serine sulfhydrylase activity. TtCsa1 showed cysteine synthase activity with high K_m for O-acetylserine and low K_m for sulfide and also had serine sulfhydrylase activity toward serine. Both TtCbs1 and TtCsa1 catalyzed hydrogen sulfide producing. TtCBS1 knockdown and TtCSA1 knockout mutants affected cysteine and glutathione synthesis. TtCbs1 and TtCsa1 are involved in cysteine synthesis through two different pathways in T. thermophila.

Human intestinal parasitic infection: a narrative review on global prevalence and epidemiological insights on preventive, therapeutic and diagnostic strategies for future perspectives

INTRODUCTION

Intestinal parasitic infection (IPI) is a global health concern among socioeconomically deprived communities in many developing countries. Many preventative strategies have been deployed to control IPI, however, there is a lack in standards on the techniques used to diagnose and monitor the prevalence of IPI.

AREAS COVERED

The present article will review the diseases associated with IPI and discuss the current IPI control strategies such as the water, sanitation, and hygiene (WASH) interventions, community-led total sanitation (CLTS) approach, and regular anthelminthic treatments. For the first time, this review will also evaluate all currently practised diagnostic techniques for the detection of intestinal parasites and provide insights on future IPI control strategies.

EXPERT OPINION

Advanced and improved diagnostic methods such as qPCR coupled with a high-resolution melting curve, aptamers, biosensors, and detection of extracellular vesicles can be used for detection of IPI. Vaccination against intestinal parasites can be made available to increase antibodies to interfere with the blood-feeding process by the parasites, which subsequently reduces the reproductive rates of the parasites. These methods collectively can serve as future management strategies for intestinal parasitic infections.

Trypanocidal Essential Oils: A Review

Trypanosomiases are diseases caused by parasitic protozoan trypanosomes of the genus Trypanosoma. In humans, this includes Chagas disease and African trypanosomiasis. There are few therapeutic options, and there is low efficacy to clinical treatment. Therefore, the search for new drugs for the trypanosomiasis is urgent. This review describes studies of the trypanocidal properties of essential oils, an important group of natural products widely found in several tropical countries. Seventy-seven plants were selected from literature for the trypanocidal activity of their essential oils. The main chemical constituents and mechanisms of action are also discussed. In vitro and in vivo experimental data show the therapeutic potential of these natural products for the treatment of infections caused by species of Trypanosoma.

Malaria parasite plasmepsins: More than just plain old degradative pepsins

Plasmepsins are a group of diverse aspartic proteases in the malaria parasite Plasmodium Their functions are strikingly multifaceted, ranging from hemoglobin degradation to secretory organelle protein processing for egress, invasion, and effector export. Some, particularly the digestive vacuole plasmepsins, have been extensively characterized, whereas others, such as the transmission-stage plasmepsins, are minimally understood. Some (e.g. plasmepsin V) have exquisite cleavage sequence specificity; others are fairly promiscuous. Some have canonical pepsin-like aspartic protease features, whereas others have unusual attributes, including the nepenthesin loop of plasmepsin V and a histidine in place of a catalytic aspartate in plasmepsin III. We have learned much about the functioning of these enzymes, but more remains to be discovered about their cellular roles and even their mechanisms of action. Their importance in many key aspects of parasite biology makes them intriguing targets for antimalarial chemotherapy. Further consideration of their characteristics suggests that some are more viable drug targets than others. Indeed, inhibitors of invasion and egress offer hope for a desperately needed new drug to combat this nefarious organism.

Targeting Parasite-Produced Macrophage Migration Inhibitory Factor as an Antivirulence Strategy With Antibiotic-Antibody Combination to Reduce Tissue Damage

Targeting virulence factors represents a promising alternative approach to antimicrobial therapy, through the inhibition of pathogenic pathways that result in host tissue damage. Yet, virulence inhibition remains an understudied area in parasitology. Several medically important protozoan parasites such as Plasmodium, Entamoeba, Toxoplasma, and Leishmania secrete an inflammatory macrophage migration inhibitory factor (MIF) cytokine homolog, a virulence factor linked to severe disease. The aim of this study was to investigate the effectiveness of targeting parasite-produced MIF as combination therapy with standard antibiotics to reduce disease severity. Here, we used Entamoeba histolytica as the model MIF-secreting protozoan, and a mouse model that mirrors severe human infection. We found that intestinal inflammation and tissue damage were significantly reduced in mice treated with metronidazole when combined with anti-E. histolytica MIF antibodies, compared to metronidazole alone. Thus, this preclinical study provides proof-of-concept that combining antiparasite MIF-blocking antibodies with current standard-of-care antibiotics might improve outcomes in severe protozoan infections.

Initial Evidences of Salt and Pepper Retinal Lesions (SPRL) in Patients with Intestinal Protozoan Infections in Iran

BACKGROUND

It is made clear that salt and pepper retinal lesion (SPRL) has subsequently associated with the infection with Giardia lamblia (G. lamblia). However, little is known regarding the prevalence of SPRL among patients suffered from parasitic infections in the world.

OBJECTIVE

This study aimed to determine the prevalence of SPRL among patients with intestinal protozoan infections, for the first time, in Sari, northern Iran.

METHODS

In this case-control study, a total of 150 subjects participated: 75 were in the patients group diagnosed to have an intestinal parasite and 75 in the control group without any intestinal infection. Fecal samples were obtained from all participants and examined with wet mount and formalin-ether methods. The retina of both groups was examined by an ophthalmologist.

RESULTS

Overall, salt and pepper retinal changes were diagnosed in 12 (16 %) patients with at least one parasitic infection (7 females and 5 males). G. lamblia was diagnosed in 6 subjects (50%), Blastocystis hominis in 5 (41.6%), and Entamoeba coli in 1 (8.3 %). Most of the patients (58.3%) had a mild infection. Bilateral retinal involvement was observed in 75% of the patients. Furthermore, macula involvement was observed in 91.7 % with SPRL.

CONCLUSION

Our findings indicated the relatively high prevalence of SPRL in subjects with giardiasis and blastocystosis. It can be concluded that not only G. lamblia but also B. hominis can cause SPRL in Sari, Iran. Further studies are needed to find other etiologic parasites able to cause retinal damages.

Inhibition survey with phenolic compounds against the δ- and η-class carbonic anhydrases from the marine diatom thalassiosira weissflogii and protozoan Plasmodium falciparum

The inhibition of δ- and η-class carbonic anhydrases (CAs; EC 4.2.1.1) was poorly investigated so far. Only one δ-CA, TweCA from the diatom Thalassiosira weissflogii, and one η-CA, PfCA, from Plasmodium falciparum, have been cloned and characterised to date. To enrich δ- and η-CAs inhibition profiles, a panel of 22 phenols was investigated for TweCA and PfCA inhibition. Some derivatives showed effective, sub-micromolar inhibition of TweCA (K_Is 0.81–65.4 µM) and PfCA (K_Is 0.62–78.7 µM). A subset of compounds demonstrated a significant selectivity for the target CAs over the human physiologically relevant ones. This study promotes the identification of new potent and selective inhibitors of TweCA and PfCA, which could be considered as leads for finding molecular probes in the study of carbon fixation processes (in which TweCA and orthologue enzymes are involved) or drug candidates in the treatment of malaria.

An Overview of Drug Resistance in Protozoal Diseases

Protozoan diseases continue to be a worldwide social and economic health problem. Increased drug resistance, emerging cross resistance, and lack of new drugs with novel mechanisms of action significantly reduce the effectiveness of current antiprotozoal therapies. While drug resistance associated to anti-infective agents is a reality, society seems to remain unaware of its proportions and consequences. Parasites usually develops ingenious and innovative mechanisms to achieve drug resistance, which requires more research and investment to fight it. In this review, drug resistance developed by protozoan parasites Plasmodium, Leishmania, and Trypanosoma will be discussed.

Global selective sweep of a highly inbred genome of the cattle parasite Neospora caninum

Neospora caninum, a cyst-forming apicomplexan parasite, is a leading cause of neuromuscular diseases in dogs as well as fetal abortion in cattle worldwide. The importance of the domestic and sylvatic life cycles of Neospora, and the role of vertical transmission in the expansion and transmission of infection in cattle, is not sufficiently understood. To elucidate the population genomics of Neospora, we genotyped 50 isolates collected worldwide from a wide range of hosts using 19 linked and unlinked genetic markers. Phylogenetic analysis and genetic distance indices resolved a single genotype of N. caninum Whole-genome sequencing of 7 isolates from 2 different continents identified high linkage disequilibrium, significant structural variation, but only limited polymorphism genome-wide, with only 5,766 biallelic single nucleotide polymorphisms (SNPs) total. Greater than half of these SNPs (∼3,000) clustered into 6 distinct haploblocks and each block possessed limited allelic diversity (with only 4 to 6 haplotypes resolved at each cluster). Importantly, the alleles at each haploblock had independently segregated across the strains sequenced, supporting a unisexual expansion model that is mosaic at 6 genomic blocks. Integrating seroprevalence data from African cattle, our data support a global selective sweep of a highly inbred livestock pathogen that originated within European dairy stock and expanded transcontinentally via unisexual mating and vertical transmission very recently, likely the result of human activities, including recurrent migration, domestication, and breed development of bovid and canid hosts within similar proximities.