Parasitic Infections Research Articles

Role of inflammasomes in Toxoplasma and Plasmodium infections.

The detection of pathogen-associated molecular patterns (PAMPs) or damage-associated molecular patterns (DAMPs) by multimeric protein complexes, known as inflammasomes, triggers an inflammatory response, which is a critical component of the innate immune system. This inflammatory response plays a pivotal role in host resistance against parasitic infections, presenting a significant global health challenge. We systematically searched for relevant articles from the Pubmed and the Web of Science database to summarize current insights into how inflammasomes function in preventing infections caused by the apicomplexan parasites Toxoplasma and Plasmodium. In vivo and in vitro studies have extensively explored inflammasomes such as the absent in melanoma 2 (AIM2), NLR family pyrin-containing protein 1 (NLRP1), NLRP3, and NLRP12 inflammasomes, alongside noncanonical inflammasomes, with particular emphasis on the NLRP1 and the NLRP3 inflammasome during Toxoplasma gondii infection or the AIM2 and the NLRP3 inflammasome at various stages of Plasmodium infection. Toxoplasma gondii interacts with inflammasomes to activate or inhibit immune responses. Inflammasomes control parasite burden and parasite-induced cell death, contribute to immune recognition and inflammatory responses and thus influence apicomplexan parasite-associated pathogenesis and the severity of clinical outcomes. Hence, inflammasomes play crucial roles in the progression and outcomes of toxoplasmosis and malaria. A comprehensive understanding of how parasitic infections modulate inflammasome activity enhances insight into host immune responses against parasites.

The parasitic copepod, Sarcotretes scopeli Jungersen, 1911 castrate its mesopelagic fish host Benthosema glaciale

AbstractThe mesopelagic fish Benthosema glaciale [Actinopterygii: Myctophiformes: Myctophidae], abundant in open ocean and deep fjords, is targeted for future exploitation despite existing knowledge gaps on population vital rates. Among these gaps, the vulnerability to pathogens is poorly understood. Parasites rely on the metabolic energy of their host and infections might compromise host physiology and behaviour, which in turn, may affect growth and survival. Parasitic infections by the copepod Sarcotretes scopeli [Crustacea: Copepoda: Pennellidae] have frequently been recorded from the North Atlantic, including west Norwegian fjords. In this paper we present data on how S. scopeli infection affect reproductive investment, energetic status, and growth of its host, the mesopelagic fish B. glaciale. Our results indicate that (i) S. scopeli reduce reproductive investment (measured as gonadosomatic index GSI) of both female and male B. glaciale; (ii) that the energy storage (hepatosomatic index HSI) appeared unaffected in female B. glaciale, while infected male hosts have higher HSI than uninfected, and (iii) that infected fish are in poorer condition than uninfected. These findings may indicate that S. scopeli could have a significant regulatory impact on B. glaciale populations.

Giant cerebellar neurocysticercosis masquerading a primary central nervous system neoplasm – A case report with review of literature

Background: Neurocysticercosis (NCC) is one of the leading parasitic infections of the brain. Giant NCC is rare, with only two cases of cerebellar involvement reported till now. In the presence of a host immune response, these giant NCCs can mimic primary central nervous system neoplasms. The objective of this article is to report a rare case of giant cerebellar NCC and its management strategy with a literature review. Case Description: A young male presented with a giant cerebellar ring-enhancing mass with features of raised intracranial pressure, and surgical excision was done. The patient made an uneventful recovery. Conclusion: Surgical excision is safe for NCC, especially in the presence of a diagnostic dilemma.

Asymptomatic parasitic worm thelazia callipaeda infection found during phacoemulsification: A case report

Introduction:We report a case of asymptomatic thelazia callipaeda infection discovered incidentally during phacoemulsification cataract surgery in March 2024. Case presentation: A 77-year-old male patient presented with complaints of blurred vision. During a slit-lamp examination, trichiasis was observed, but the patient had no foreign body sensation or itching. He was diagnosed with cataract and underwent phacoemulsification cataract surgery. During the surgery, a white, wriggling worm was discovered in the conjunctival sac and removed. It was later identified as thelazia callipaeda. The surgical eye was thoroughly washed and received anti-inflammatory medication postoperatively. No recurrence or new symptoms were reported during the 3-month follow-up period. Conclusions: Thelazia callipaeda infection can be asymptomatic and incidentally discovered. A detailed preoperative examination, such as turning over the upper and lower eyelids to check the conjunctival sac, is necessary before the surgery. When a worm is discovered during surgery, it is crucial to remove it completely and thoroughly clean and disinfect the conjunctival sac.

Current vaccines, experimental immunization trials, and new perspectives to control selected vector borne blood parasites of veterinary importance

Parasite infections transmitted by vectors such as ticks and blood-sucking arthropods pose a significant threat to both human and animal health worldwide and have a substantial economic impact, particularly in the context of worsening environmental conditions. These infections can manifest in a variety of symptoms, including fever, anemia, jaundice, enlarged spleen, neurological disorders, and lymphatic issues, and can have varying mortality rates. In this review, we will focus on the current state of available vaccines, vaccine research approaches, and trials for diseases caused by vector-borne blood parasites, such as Babesia, Theileria, Anaplasma, and Trypanosoma, in farm animals. Control measures for these infections primarily rely on vector control, parasiticidal drug treatments, and vaccinations for disease prevention. However, many of these approaches have limitations, such as environmental concerns associated with the use of parasiticides, acaricides, and insecticides. Additionally, while some vaccines for blood parasites are already available, they still have several drawbacks, including practicality issues, unsuitability in non-endemic areas, and concerns about spreading other infectious agents, particularly in the case of live vaccines. This article highlights recent efforts to develop vaccines for controlling blood parasites in animals. The focus is on vaccine development approaches that show promise, including those based on recombinant antigens, vectored vaccines, and live attenuated or genetically modified parasites. Despite intensive research, developing effective subunit vaccines against blood stage parasites remains a challenge. By learning from previous vaccine development efforts and using emerging technologies to define immune mechanisms of protection, appropriate adjuvants, and protective antigens, we can expand our toolkit for controlling these burdensome diseases.

The burden and trend of intestinal parasitosis among women at Berekum, Ghana: a 9-year retrospective study.

Intestinal parasitic infections(IPIs) are serious global public health issues, especially in low and middle-income countries. These parasites can cause high morbidity and mortality, especially in immunocompromised individuals, and can easily be transmitted by consumption of contaminated food or water or by penetration of skin and mucous membranes. We retrospectively analyzed all archived data from stool examination reports at the Parasitology Unit of Precise Health Diagnostic Services, Berekum for the prevalence and trends of parasitic infections spanning a period of 9 years (2013-2021). The data was retrieved and exported to IBM SPSS v.26 for statistical analysis. Descriptive data was summarized as proportions and presented in tables and charts. Pearson Chi-Square test (χ2) or Fisher's exact test was used to test for a statistical association between demographic factors and intestinal parasitic infections. P value was significant at < 0.05. A total of 9,217 records of stool examinations were retrieved. Almost half (48.45%) of the data were from patients aged between 20 and 29 years. An overall prevalence of intestinal parasitic infections of 21.20% was observed in this study. Patients aged 70 to 79 had the highest prevalence of the IPIs (44.44%). The parasites recovered in this study were intestinal flagellates, Entamoeba coli, Hookworm, Entamoeba histolytica/dispar, Ascaris lumbricoides, Enterobius vermicularis, Strongyloides stercoralis and Hymenolepis nana. The intestinal flagellates had the highest prevalence (98.31%) compared to the other intestinal parasites recovered. Intestinal parasitic infections had the highest prevalence in the year 2020 (28.56%) and lowest in 2018 (11.78%). An overall prevalence of 21.20% of intestinal parasitic infection was found. The majority of the parasites reported were intestinal flagellates (98.31%). The trend analysis revealed that the overall prevalence fluctuated across the entire period from 2013 to 2021.

Prevalence of intestinal parasitic helminths and its associated risk factors in Mekaneselam Town, South Wollo, Ethiopia.

Intestinal parasitic (IP) infections caused by helminths are among the most significant public health concerns that mainly affect deprived people in Sub-Sahara African countries. The current study aimed to determine the prevalence and associated risk factors of intestinal parasitic helminths among patients attending Mekaneselam hospital. In this cross-sectional study conducted from August 2022 to February 2023, stool specimens were collected and examined microscopically to detect intestinal helminths using direct wet-mount and formal-ether concentration techniques. A structured questionnaire was employed to obtain information regarding the socio-demographic characteristics and associated risk factors. Data were analyzed via appropriate univariate and multivariable logistic regression methods using SPSS version 25.0. The overall prevalence of the parasitic helminths was 51 (12.6%) out of 404 patients attending in Mekaneselam town during the study period. In this study, seven species of intestinal helminths were detected, with Ascaris lumbricoides (5.7%) being the most prevalent followed by Trichuris trichiura (2.2%). Significant positive associations were observed between intestinal helminths infection and the socio-demographic characteristics including marital status (χ2 = 7.97, p = 0.047), educational level (χ2 = 9.34, p = 0.025) and residence (χ2 = 3.90, p = 0.048). The odds of being infected with IP were three times higher among divorced patients than married individuals (AOR = 3.21, CI = 1.15-8.96, p = 0.03). Illiterate individuals were three times (AOR = 2.61, CI = 1.24-5.49, p = 0.011) and those who attended primary school were two times (AOR = 2.3, CI = 1.029-5.143, p = 0.042), more likely to have helminthic infections. Participants who did not wash their hands after using the toilet were five times more likely to acquire IP helminths than those who did (AOR = 4.36, CI = 2.83-6.72, p = 0.000). In the case of the feeding habit, study subjects who ate unwashed vegetables were more likely to acquire helminths than those who did not eat unwashed vegetables (AOR = 5. 43, CI = 4.33-23.77, p = 0.000). This study highlighted a substantial prevalence of intestinal helminths infections (12.6%) in the study area, warranting the urgent need for attention and interventions from relevant public health authorities.

Gastrointestinal Helminth Infections in Dogs in Sheep and Goat Farms in Greece: Prevalence, Involvement of Wild Canid Predators and Use of Anthelmintics

The objectives of the present work were the investigation of gastrointestinal parasitic infections in dogs in small ruminant farms in Greece, the elucidation of potential predictors for these infections and the description of practices related to administration of anthelmintics to dogs. This study was carried out in 444 small ruminant farms in Greece. Faecal samples were collected directly from the rectum of the dogs in the farms. The samples were processed by means of conventional parasitological techniques, specifically, a combined sedimentation flotation technique. There were dogs in 92.8% of the farms, with a median number of four dogs per farm. The following variables were associated with the presence of dogs in the farms: the presence of wild mammal predators near the farms, the increased daily period of farmers’ presence at the farm, goats as the livestock species at the farm and the management system applied in the farm. Helminth eggs were detected in samples from 72.6% of the farms. The main helminth eggs detected were those of hookworms (Uncinaria/Ancylostoma) and Toxocara canis, in 68.6% and 51.3% of the farms, respectively. In our multivariable analyses, an association emerged between the presence of canid predators near a farm and the detection of these helminths in faecal samples: in 76% and 60% of the samples, respectively, versus in 58% and 39% of the samples from farms with no canid presence. Of farmers with dogs, 16.0% reported that they omitted the administration of anthelmintics to the animals. In multivariable analysis, the semi-extensive or extensive management system applied in the farm, the lower annual milk production per animal and the lack of collaboration with a veterinary practice were the significant predictors for the omission of anthelmintic administration to the farm dogs. There was also a clear association in the omission of anthelmintic administration to the dogs and to the livestock on the farm. The most frequently administered anthelmintic was praziquantel, which was used in 93.6% of the farms.

The variety of abomasal nematode communities of captive and free-roaming populations of European bison, Bison bonasus (L.): a morphometric and molecular approach.

Most studies concerning parasitic infections in European bison have been performed on free-ranging animals: comparatively little is known about the abomasal nematodes of captive wisents, which are widely used in reintroduction programmes. The aim of the study was to determine the infection level and species composition of abomasal nematodes in captive European bison in enclosures (including zoos) and breeding centres compared to free-ranging individuals. It also includes a morphological analysis of the parasites based on figures and measurement data. Altogether, 11 species of nematodes were detected, with both captive and free-ranging animals demonstrating similar species compositions. Among those, 2 species of blood-sucking nematodes were detected, including Ashworthius sidemi and Haemonchus contortus. Interestingly, A. sidemi was found in almost all free-roaming animals, but only in 1 captive European bison. In addition, H. contortus was predominant in captive animals. The morphological identification was confirmed molecularly for 5 nematode species: A. sidemi, H. contortus, Ostertagia kolchida, O. ostertagi and Spiculopteragia boehmi. The identification was performed using small subunit ribosomal rDNA. The study provides the first available set of specular lengths of the gastric nematodes of European bison, and the first molecular data of O. kolchida and S. boehmi derived from the same host species. Our findings may simplify the morphometrical and molecular identification of Trichostrongylidae species infecting European bison, and can be useful in developing new management strategies for populations of this near-threatened species in Europe.

Distinct distribution and responses of IgM+, IgT1+ and IgT2+ B cells in common carp

In teleosts, the immunoglobulin classes produced by B cells are IgM, IgD, and IgT/IgZ. IgT was initially described as an immunoglobulin specialized in mucosal responses; accumulating evidence, however, shows that it is also involved in systemic immune responses. Two types of IgT/IgZ (IgT1 and IgT2) were previously described in common carp, but their further characterization was hampered by the lack of specific tool. In the current study, we developed and validated polyclonal antibodies against carp IgT1 and IgT2 and used them in combination with well validated monoclonal antibody against carp IgM (WCI12), to study the distribution of IgM+, IgT1+ and IgT2+ B cells or their secreted immunoglobulins in various mucosal and systemic organs of carp. Finally, we also preliminary assessed the B cell response to infection with the blood-borne parasite Trypanoplasma borreli. Using these tools, we report on the distinct expression of soluble immunoglobulins in systemic and mucosal compartments. IgT1 and IgM were expressed in mucosal as well as systemic organs and responded to systemic parasitic infection, whereas IgT2 was preferentially expressed at mucosal sites and did not respond to systemic infections. By studying the distribution of B cells in different organs, compartmentalization of the three B cell subtypes was observed in gills and gut, whereas splenic B cells appeared as organized clusters around ellipsoids. Our results provide insights into the distribution and to some extent the function of B cells in carp, indicating that our newly developed tools are valuable for future studies aiming at the further characterization of immune responses of carp to infections and vaccination.

Role of Eosinophils in Immunity, Allergy, and Inflammation: Friend or Foe

Eosinophils are multifunctional granulocytes involved in both protective and pathological immune responses. Traditionally recognized for their role in host defense against parasitic infections, eosinophils have gained significant attention for their involvement in allergic diseases, such as asthma, allergic rhinitis, and atopic dermatitis, where they are often considered detrimental. Eosinophils contribute to tissue damage and inflammation by releasing cytotoxic granule proteins, cytokines, and chemokines, perpetuating chronic inflammation. In conditions such as eosinophilic gastrointestinal disorders and hypereosinophilic syndrome, eosinophils infiltrate tissues and exacerbate inflammation, leading to organ dysfunction. However, eosinophils also exhibit beneficial roles, including modulating immune responses, promoting tissue repair, and maintaining tissue homeostasis. Recent research has highlighted their regulatory functions, where they interact with other immune cells to mediate both pro- and anti-inflammatory responses. The dual nature of eosinophils—both as protectors in immunity and contributors to pathology—presents a complex challenge in understanding their full impact on health and disease. Advances in biologic therapies targeting eosinophil activity, such as IL-5 inhibitors, offer promising treatment options for eosinophil-associated disorders. This review explores the diverse roles of eosinophils in immunity, allergy, and inflammation, examining both their protective and harmful functions, while discussing therapeutic strategies aimed at modulating eosinophil activity in various diseases. Keywords: Eosinophils, allergy, inflammation, immune regulation, IL-5 therapy

A Severe Case of Plasmodium falciparum Malaria in a 44-Year-Old Caucasian Woman on Return to Western Romania from a Visit to Nigeria

Malaria is currently the most prevalent life-threatening infectious disease in the world. In this case report, we present a 44-year-old Caucasian woman with a low level of education and no significant past medical history who presented to the emergency room of the Emergency County Hospital of Arad, Romania, with a general affected state, a fever of 38.5 °C, chills, weakness, headache, muscle pain, nausea, icterus, and watery diarrheal stool. A viral infection was initially suspected, and the patient was transferred to the Infectious Diseases Department. The anamnesis revealed that the patient traveled to Nigeria (Ado Ekiti) and returned to Romania 14 days before presenting to the hospital without following antimalarial prophylaxis. A peripheral blood smear was conducted and revealed parasitemia with ring forms of Plasmodium falciparum (P. falciparum) of 10–15% within the red blood cells. Parasitemia increased within a day to 15–18%, and her health rapidly deteriorated. She was transferred to the Victor Babeș Infectious Disease Hospital in Bucharest for the urgent initiation of antimalarial treatment. The patient’s condition continued to worsen rapidly, and she succumbed to her illness due to multi-organ failure. This report details the first documented case of malaria imported from Nigeria to Romania. People traveling to malaria-endemic areas should be educated about preventing this parasitic infection, both by adopting measures to reduce the risk of mosquito bites and by using appropriate chemoprophylaxis. In the context of resuming travel after the COVID-19 pandemic, understanding and adhering to prophylactic measures is crucial to avoid tragic situations, as highlighted in this case report.

Symptomatic Entamoeba dispar Infections Among Men Who Have Sex With Men, New York City, 2018

Abstract Entamoeba histolytica is considered the primary species causing the parasitic gastrointestinal infection amebiasis. A cluster of amebiasis infections was identified in 2018 among men who have sex with men in New York City and was likely caused by Entamoeba dispar, traditionally considered to be non-pathogenic.

Conspicuous parasite modifies appearance and energetics of a marine copepod

Abstract Parasitism is an important driver of ecosystem processes. Copepods are fundamental trophic links in marine food webs and harbour many microeukaryotic parasites, but unreliable access to infected individuals limits quantitative studies of parasite infection costs. Calanus spp., (helgolandicus or finmarchicus), infected with the Yellow-Hyphal Parasite become pigmented and are found near the surface, suggesting predator-mediated dispersal. Conventional markers prevented phylogenetic inference but confirmed that the parasite is not Ichthyophonus hoferi, as previously thought. We identified the pigments, quantified the pigment content and respiration rate, and derived stable isotope signatures of infected and uninfected Calanus spp. to examine costs of infection. We found that the pigments were astaxanthin and β-carotene, associated with the host and parasite, respectively. Parasitized hosts had increased astaxanthin content, reduced respiration rate, and lower lipid content. Ultrastructure imaging revealed parasitic cells associated with lipids in the haemocoel. The changes to host phenotype have detrimental impacts on energetics and the ecology of Calanus. We discuss the role of pigments in parasite-host interactions and suggest that the parasite produces β-carotene pigment for its physiological benefits. The trade-off between physiological benefits of pigments and conspicuousness for parasites is relevant in zooplankton-host systems, as zooplankton rely heavily on transparency for survival.

Concomitant parasite infections influence tuberculosis immunopathology and favor rapid sputum conversion of pulmonary tuberculosis patients

Immunopathology of human tuberculosis (TB) in a subgroup of patients is characterized by aberrantly high concentrations of inflammatory cytokines, for example Interleukin (IL)-6. Concomitant (co-)infections by parasites can affect host immunity, but the impact on immunopathology in TB patients is poorly defined. Here we characterized a group of patients with TB ( n = 76) from Ghana with different protozoan and helminth co-infections. Plasma cytokines were measured at the onset of disease and anti-mycobacterial treatment efficacy was monitored during disease course. A subgroup of TB patients had co-infections with protozoan (n = 19) or helminth (n = 16) parasites. Plasma analyses for candidate cytokines identified lower levels of IL-6 in parasite co-infected patients with TB. Moreover, it took less time for co-infected patients to become sputum-negative for Mycobacterium tuberculosis during treatment. These results indicated an influence of parasite co-infections on immunopathology in TB and suggested positive effects on treatment efficacy.

A lightweight deep-learning model for parasite egg detection in microscopy images.

Intestinal parasitic infections are still a serious public health problem in developing countries, and the diagnosis of parasitic infections requires the first step of parasite/egg detection of samples. Automated detection can eliminate the dependence on professionals, but the current detection algorithms require large computational resources, which increases the lower limit of automated detection. Therefore, we have designed a lightweight deep-learning model, YAC-Net, to achieve rapid and accurate detection of parasitic eggs and reduce the cost of automation. This paper uses the ICIP 2022 Challenge dataset for experiments, and the experiments are conducted using fivefold cross-validation. The YOLOv5n model is used as the baseline model, and then two improvements are made to the baseline model based on the specificity of the egg data. First, the neck of the YOLOv5n is modified to from a feature pyramid network (FPN) to an asymptotic feature pyramid network (AFPN) structure. Different from the FPN structure, which mainly integrates semantic feature information at adjacent levels, the hierarchical and asymptotic aggregation structure of AFPN can fully fuse the spatial contextual information of egg images, and its adaptive spatial feature fusion mode can help the model select beneficial feature and ignore redundant information, thereby reducing computational complexity and improving detection performance. Second, the C3 module of the backbone of the YOLOv5n is modified to a C2f module, which can enrich gradient information, improving the feature extraction capability of the backbone. Moreover, ablation studies are designed by us to verify the effectiveness of the AFPN and C2f modules in the process of model lightweighting. The experimental results show that compared with YOLOv5n, YAC-Net improves precision by 1.1%, recall by 2.8%, the F1 score by 0.0195, and mAP_0.5 by 0.0271 and reduces the parameters by one-fifth. Compared with some state-of-the-art detection methods, YAC-Net achieves the best performance in precision, F1 score, mAP_0.5, and parameters. The precision, recall, F1 score, mAP_0.5, and parameters of our method on the test set are 97.8%, 97.7%, 0.9773, 0.9913, and 1,924,302, respectively. Compared with the baseline model, YAC-Net optimizes the model structure and simplifies the parameters while ensuring the detection performance. It helps to reduce the equipment requirements for performing automated detection and can be used to realize the automatic detection of parasite eggs under microscope images.

Detection of biliary trematodes in sheep and goats from northern and central Portugal

Fasciolosis and dicrocoeliosis are severe parasitic infections that result in substantial economic damages to livestock farming globally as a consequence of reduced productivity and viscera condemnation. Molecular tests such as polymerase chain reaction (PCR) can detect Fasciola hepatica and Dicrocoelium dendriticum DNA with high sensitivity and specificity. In this study, we aimed to assess the presence of F. hepatica and D. dendriticum by PCR-based techniques in 400 small ruminant bile samples retrieved from central Portugal. Additionally, we conducted genetic characterisation of F. hepatica and D. dendriticum in these samples. Only one of the 400 bile samples (0.25%; 95% confidence interval [CI]: 0.01–1.39) examined by PCR tested positive for F. hepatica, and two samples (0.50%, 95% CI: 0.06–1.79) tested positive for D. dendriticum. Our findings indicate a low prevalence of F. hepatica and D. dendriticum in Portuguese small ruminants, underscoring the need to investigatefactors leading to meat rejection in slaughterhouses. Implementing effective parasite control measures is crucial to minimise economic losses and improve food safety. Addressing these infections and deploying targeted control strategies can enhance livestock production sustainability and ensure safe, high-quality meat products for consumers.

Prevalence of intestinal parasites in street dwellers attending a shelter in Cali, Colombia.

Intestinal parasitic infections represent a public health problem, especially among vulnerable populations. There are few studies on the prevalence and determinants of intestinal parasites infections in street dwellers, who may experience significant health and socioeconomic implications. Understanding the prevalence and associated factors of intestinal parasites in this population is crucial for targeted interventions to mitigate the spread of these infections. To determine the prevalence of intestinal parasites in street dwellers attending a shelter in Cali, Colombia. We selected 66 participants who met the inclusion criteria. We collected serial stool samples for laboratory evaluation and sociodemographic data, and information on their hygiene habits and addictions. Seventy-six percent of the participants had intestinal parasites or commensals, with 30% presenting monoparasitism, 46% polyparasitism, and 20% eosinophilia. Blastocystis spp. was the most common organism (68.18%), followed by Endolimax nana (34.85%) and Entamoeba coli (18.18%). The most common pathogens were the Entamoeba histolytica/E. dispar/E. moshkovskii complex (10.61%) and hookworms (9.09%). We evaluated prevalence-related determinants. Intestinal parasitism is a health problem among street dwellers in Cali. A serial examination is recommended for diagnosing intestinal parasitic infection, especially in cases of low parasite loads. Campaigns should be established to reduce the prevalence of these parasites in populations at risk of complications.

Comparative genomics of Plasmodium yoelii nigeriensis N67 and N67C: genome-wide polymorphisms, differential gene expression, and drug resistance

BackgroundThe study of rodent malaria parasites has significantly advanced our understanding of malaria parasite biology and host responses to parasite infections. There are four well-characterized rodent malaria parasite species (Plasmodium yoelii, P. chabaudi, P. berghei, and P. vinckei). Each species also has multiple strains that cause different disease phenotypes. P. yoelii nigeriensis N67C and N67, two isogenic parasites, are particularly intriguing as they differ in virulence and incite different immune responses in mice. The genome of the N67 parasite has been assembled recently, but not that of N67C. This study used PacBio HiFi sequencing data to assemble the N67C genome, compared the two genomes, and performed RNA sequencing to identify polymorphisms and differentially expressed genes (DEGs).ResultsThe assembled N67C parasite genome consisted of 16 scaffolds and three contigs of approximately 22.5 Mb with 100% and 96.6% completeness based on well-characterized single-copy orthologs specific to the Apicomplexa phylum and the Plasmodium genus, respectively. A comparison between the annotated N67C and N67 genomes revealed 133 single nucleotide polymorphisms (SNPs) and 75 indels. Among the polymorphic sites, an S (N67) to N (N67C) amino acid substitution at position 114 (S114N) in the dihydrofolate reductase-thymidylate synthase (DHFR-TS) confers resistance to pyrimethamine in mice. Additionally, 60 differentially expressed single-copy genes (DEGs) were detected after comparing mRNA levels between the two parasites. Starting with the predicted and annotated 5,681 N67C and 5,749 N67 genes, we identified 4,641 orthogroups that included at least one gene from the four P. yoelii parasites (N67, N67C, 17X, and YM), whereas 758 orthogroups showed subspecies or strain-specific patterns.ConclusionThe identification of polymorphic sites between the N67 and N67C genomes, along with the detection of the DEGs, may provide crucial insights into the variations in parasite drug responses and disease severity between these two isogenic parasites. The functional characterization of these genetic differences and candidate genes will deepen our understanding of disease mechanisms and pave the way for developing more effective control measures against malaria.

Critical and diverse role of alarmin cytokines in parasitic infections

Alarmin cytokines including IL-25, IL-33, and thymic stromal lymphopoietin (TSLP) function as danger signals to trigger host immunity in response to tissue injury caused by pathogenic factors such as parasitic infections. Parasitic diseases also provide an excellent context to study their functions and mechanisms. Numerous studies have indicated that alarmin cytokine released by non-immune cells such as epithelial and stromal cells induce the hosts to initiate a type 2 immunity that drives parasite expulsion but also host pathology such as tissue injury and fibrosis. By contrast, alarmin cytokines especially IL-33 derived from immune cells such as dendritic cells may elicit an immuno-suppressive milieu that promotes host tolerance to parasites. Additionally, the role of alarmin cytokines in parasite infections is reported to depend on species of parasites, cellular source of alarmin cytokines, and immune microenvironment, all of which is relevant to the parasitic sites or organs. This narrative review aims to provide information on the crucial and diverse role of alarmin cytokines in parasitic infections involved in different organs including intestine, lung, liver and brain.