Pub Date : 2026-02-06DOI: 10.1016/j.ijpara.2026.104803
Sohini Kumar, Zhiqiang Pang, Elizabeth Siciliani, Armando Jardim, Jianguo Xia, Thavy Long
Resistance to macrocyclic lactone (ML) preventives in the canine heartworm Dirofilaria immitis is an emerging concern worldwide. Although ML-resistant isolates of D. immitis are genetically distinct from wildtype populations, little is known about their drug resistance mechanisms. To address this gap, we used untargeted metabolomics to characterize and compare the excreted/secreted metabolic profile of drug-susceptible Missouri (MO) and -resistant JYD-34 isolates in the presence or not of ivermectin (IVM). Both isolates showed differences in their baseline metabolomic profiles, which became substantially distinct following IVM treatment. Further analysis indicated that tryptophan metabolism (TM) was significantly different between MO and JYD-34. We identified varying enrichment profiles of metabolites linked to the kynurenine pathway (KP). Furthermore, our study suggested that IVM treatment triggers an increased release of metabolites linked to KP in MO only, suggesting a potential role of KP in modulating the host immune system.
{"title":"Metabolomic analysis of macrocyclic lactone susceptible and resistant isolates of Dirofilaria immitis.","authors":"Sohini Kumar, Zhiqiang Pang, Elizabeth Siciliani, Armando Jardim, Jianguo Xia, Thavy Long","doi":"10.1016/j.ijpara.2026.104803","DOIUrl":"https://doi.org/10.1016/j.ijpara.2026.104803","url":null,"abstract":"<p><p>Resistance to macrocyclic lactone (ML) preventives in the canine heartworm Dirofilaria immitis is an emerging concern worldwide. Although ML-resistant isolates of D. immitis are genetically distinct from wildtype populations, little is known about their drug resistance mechanisms. To address this gap, we used untargeted metabolomics to characterize and compare the excreted/secreted metabolic profile of drug-susceptible Missouri (MO) and -resistant JYD-34 isolates in the presence or not of ivermectin (IVM). Both isolates showed differences in their baseline metabolomic profiles, which became substantially distinct following IVM treatment. Further analysis indicated that tryptophan metabolism (TM) was significantly different between MO and JYD-34. We identified varying enrichment profiles of metabolites linked to the kynurenine pathway (KP). Furthermore, our study suggested that IVM treatment triggers an increased release of metabolites linked to KP in MO only, suggesting a potential role of KP in modulating the host immune system.</p>","PeriodicalId":13725,"journal":{"name":"International journal for parasitology","volume":" ","pages":"104803"},"PeriodicalIF":3.2,"publicationDate":"2026-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146142390","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-01DOI: 10.1016/S0020-7519(26)00020-2
{"title":"Aims and scope and Editorial board","authors":"","doi":"10.1016/S0020-7519(26)00020-2","DOIUrl":"10.1016/S0020-7519(26)00020-2","url":null,"abstract":"","PeriodicalId":13725,"journal":{"name":"International journal for parasitology","volume":"56 2","pages":"Article 104789"},"PeriodicalIF":3.2,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146096025","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-01DOI: 10.1016/j.ijpara.2025.08.004
Charlotte O. Moore , Caroline V. Andrews , Erin M. Lemley , Michelli Inacio Gonçalves Funnicelli , Marcos Rogério André , Edward B. Breitschwerdt , Erin Lashnits
Small wildlife species host flea and tick species that can also infest or transmit pathogens to domestic animals and humans, including Anaplasma, Babesia, Bartonella, Borrelia, Ehrlichia, and Rickettsia species. Despite their zoonotic potential, little is known regarding the prevalence, diversity, and epidemiology of these pathogens. Therefore, we aimed to survey the ectoparasites found on Eastern Cottontail Rabbits (rabbits), Eastern Grey Squirrels (squirrels), and Virginia Opossums (opossums) in south-central Wisconsin, and describe the prevalence of select pathogens. Ectoparasites were opportunistically collected from small mammals, then identified to the species level, pooled, washed, and DNA extracted for quantitative PCR (qPCR) to detect Anaplasmataceae, Apicomplexa, Bartonella, hemotropic Mycoplasma, and Rickettsia. To analyze the genomic diversity of uncharacterized Bartonella, three flea pools were subject to metagenomic sequencing. Cediopsylla simplex and Haemaphysalis leporispalustris were the most common ectoparasites on rabbits, while Orchopeas howardi was most common on squirrels and opossums. Bartonella species were detected in C. simplex pools (n = 52), most commonly two distinct Bartonella alsatica-like bacteria (38 %; 20/52). Bartonella durdenii, definitively identified by metagenomic sequencing, was detected in 42 % (13/31) of O. howardi pools from squirrels. From metagenomic sequencing, B. alsatica-like species displayed a 4.8 % dissimilarity rate while B. durdenii displayed a 0.4 % dissimilarity rate. Sequencing of one B. alsatica-like flea pool also identified phage-associated genes not found in the B. alsatica genome. Rickettsia felis (n = 1) and opossum-associated hemotropic Mycoplasma sp. (n = 2) were detected in O. howardi from opossums. Rickettsia bellii and Anaplasma sp. were detected in Haemaphysalis leporispalustris from rabbits. These findings reinforce the value of metagenomic sequencing, facilitating the correct identification of B. durdenii and identifying genes not found in the type strain, specifically phage related genes. Due to the known zoonotic potential of B. alsatica, further examination of B. alsatica-like and B. durdenii pathogenicity is warranted.
{"title":"Wildlife fleas and ticks in Wisconsin, USA: unrecognized vectors of bacterial pathogens","authors":"Charlotte O. Moore , Caroline V. Andrews , Erin M. Lemley , Michelli Inacio Gonçalves Funnicelli , Marcos Rogério André , Edward B. Breitschwerdt , Erin Lashnits","doi":"10.1016/j.ijpara.2025.08.004","DOIUrl":"10.1016/j.ijpara.2025.08.004","url":null,"abstract":"<div><div>Small wildlife species host flea and tick species that can also infest or transmit pathogens to domestic animals and humans, including <em>Anaplasma, Babesia, Bartonella, Borrelia, Ehrlichia,</em> and <em>Rickettsia</em> species. Despite their zoonotic potential, little is known regarding the prevalence, diversity, and epidemiology of these pathogens. Therefore, we aimed to survey the ectoparasites found on Eastern Cottontail Rabbits (rabbits), Eastern Grey Squirrels (squirrels), and Virginia Opossums (opossums) in south-central Wisconsin, and describe the prevalence of select pathogens. Ectoparasites were opportunistically collected from small mammals, then identified to the species level, pooled, washed, and DNA extracted for quantitative PCR (qPCR) to detect Anaplasmataceae, Apicomplexa, <em>Bartonella,</em> hemotropic <em>Mycoplasma,</em> and <em>Rickettsia.</em> To analyze the genomic diversity of uncharacterized <em>Bartonella</em>, three flea pools were subject to metagenomic sequencing. <em>Cediopsylla simplex</em> and <em>Haemaphysalis leporispalustris</em> were the most common ectoparasites on rabbits, while <em>Orchopeas howardi</em> was most common on squirrels and opossums. <em>Bartonella</em> species were detected in <em>C. simplex</em> pools (<em>n</em> = 52)<em>,</em> most commonly two distinct <em>Bartonella alsatica</em>-like bacteria (38 %; 20/52). <em>Bartonella durdenii,</em> definitively identified by metagenomic sequencing, was detected in 42 % (13/31) of <em>O. howardi</em> pools from squirrels<em>.</em> From metagenomic sequencing, <em>B. alsatica-</em>like species displayed a 4.8 % dissimilarity rate while <em>B. durdenii</em> displayed a 0.4 % dissimilarity rate. Sequencing of one <em>B. alsatica</em>-like flea pool also identified phage-associated genes not found in the <em>B. alsatica</em> genome. <em>Rickettsia felis</em> (<em>n</em> = 1) and opossum-associated hemotropic <em>Mycoplasma</em> sp. (<em>n</em> = 2) were detected in <em>O. howardi</em> from opossums<em>. Rickettsia bellii</em> and <em>Anaplasma</em> sp. were detected in <em>Haemaphysalis leporispalustris</em> from rabbits. These findings reinforce the value of metagenomic sequencing, facilitating the correct identification of <em>B. durdenii</em> and identifying genes not found in the type strain, specifically phage related genes. Due to the known zoonotic potential of <em>B. alsatica,</em> further examination of <em>B. alsatica</em>-like and <em>B. durdenii</em> pathogenicity is warranted.</div></div>","PeriodicalId":13725,"journal":{"name":"International journal for parasitology","volume":"56 2","pages":"Article 104716"},"PeriodicalIF":3.2,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144953024","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The protozoan parasite Eimeria tenella causes coccidiosis in poultry, which results in substantial economic losses to the global poultry industry. Understanding the molecular mechanisms of drug resistance in E. tenella is essential for developing effective control strategies. The goal of this study was to investigate the role of E. tenella phosphofructokinase (EtPFK1) in mediating resistance to maduramycin, a widely used anticoccidial drug. Characterization of EtPFK1 expression across developmental stages and under drug treatment revealed elevated mRNA and protein levels in sporulated oocysts and maduramycin-resistant strains. Immunofluorescence assays showed its localization in the cytoplasm and on the surface of sporozoites. To elucidate the role of EtPFK1 in maduramycin-resistant strains, an EtPFK1-overexpressing strain was generated using the drug-sensitive strain of E. tenella. Overexpression of EtPFK1 reduced the sensitivity of E. tenella to maduramycin, as demonstrated by both in vitro and in vivo assays. Specifically, the EtPFK1-overexpressing strain exhibited complete resistance to 2 ppm maduramycin and light resistance to 5 ppm, indicating that EtPFK1 contributes to the development of drug resistance in E. tenella. Additionally, EtPFK1 overexpression reduced the pathogenicity of E. tenella, as demonstrated by fewer cecal lesions and lower oocyst output in infected chickens. EtPFK1 overexpression enhanced adaptation to high-glucose environments, potentially facilitating drug resistance. These findings highlight the multifaceted role of EtPFK1 in mediating drug resistance in E. tenella and provide insight into the development of novel therapeutic interventions against coccidiosis.
{"title":"The key glycolytic enzyme phosphofructokinase is involved in Eimeria tenella resistance to maduramycin","authors":"Huanzhi Zhao , Qiping Zhao , Shunhai Zhu , Liushu Jia , Yu Yu , Jinwen Wang , Sishi Zhang , Qian Feng , Jia Yang , Bing Huang , Hui Dong , Hongyu Han","doi":"10.1016/j.ijpara.2025.08.008","DOIUrl":"10.1016/j.ijpara.2025.08.008","url":null,"abstract":"<div><div>The protozoan parasite <em>Eimeria tenella</em> causes coccidiosis in poultry, which results in substantial economic losses to the global poultry industry. Understanding the molecular mechanisms of drug resistance in <em>E. tenella</em> is essential for developing effective control strategies. The goal of this study was to investigate the role of <em>E. tenella</em> phosphofructokinase (<em>Et</em>PFK1) in mediating resistance to maduramycin, a widely used anticoccidial drug. Characterization of <em>Et</em>PFK1 expression across developmental stages and under drug treatment revealed elevated mRNA and protein levels in sporulated oocysts and maduramycin-resistant strains. Immunofluorescence assays showed its localization in the cytoplasm and on the surface of sporozoites. To elucidate the role of <em>Et</em>PFK1 in maduramycin-resistant strains, an <em>Et</em>PFK1-overexpressing strain was generated using the drug-sensitive strain of <em>E. tenella</em>. Overexpression of <em>Et</em>PFK1 reduced the sensitivity of <em>E. tenella</em> to maduramycin, as demonstrated by both in vitro and in vivo assays. Specifically, the <em>Et</em>PFK1-overexpressing strain exhibited complete resistance to 2 ppm maduramycin and light resistance to 5 ppm, indicating that <em>Et</em>PFK1 contributes to the development of drug resistance in <em>E. tenella</em>. Additionally, <em>Et</em>PFK1 overexpression reduced the pathogenicity of <em>E. tenella</em>, as demonstrated by fewer cecal lesions and lower oocyst output in infected chickens. <em>Et</em>PFK1 overexpression enhanced adaptation to high-glucose environments, potentially facilitating drug resistance. These findings highlight the multifaceted role of <em>Et</em>PFK1 in mediating drug resistance in <em>E. tenella</em> and provide insight into the development of novel therapeutic interventions against coccidiosis.</div></div>","PeriodicalId":13725,"journal":{"name":"International journal for parasitology","volume":"56 2","pages":"Article 104720"},"PeriodicalIF":3.2,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144953008","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-01DOI: 10.1016/j.ijpara.2025.08.010
Eloy Gonzales-Gustavson , Francesco Pizzitutti , Gabrielle Bonnet , Claudio Muro , Ricardo Gamboa , Javier A. Bustos , Sarah Gabriël , William K. Pan , Héctor H. Garcia , Seth O'Neal , for the CWGP
Taenia solium is a zoonotic parasite causing significant health and economic burdens, with complex transmission dynamics that demand improved control strategies. This study examines how infection and reinfection affect cyst development in pigs and how acquired immunity constrains parasite burden. A total of 116 pigs were purchased from commercial farms in northern Peru and housed under controlled conditions. Of these, 110 pigs were allocated to 18 experimental groups to evaluate the impact of single and repeated infections with varying doses of T. solium eggs and to model the number of live cysts produced based on dose and age at infection. Gravid proglottids collected from human cases were used to prepare viable egg pools. Infections were administered orally via esophageal catheterization, and pigs were necropsied 10 weeks after the final infection to quantify cyst burden. A negative binomial regression model assessed the influence of infection dose, prior infection, age, and other factors. No significant differences in cyst counts were found between singly infected and reinfected pigs, regardless of initial or reinfection doses, highlighting that infection induces strong acquired immunity that prevents subsequent infections. A dose–response analysis indicated that cyst burden follows a power relationship with egg dose. Integrating data from both single and reinfected pigs into a unified model improved prediction precision. Furthermore, incorporating age at infection allowed us to model the combined effects of acquired and innate immunity, reflecting changes in susceptibility over time. These findings demonstrate that a single exposure to T. solium eggs can generate robust protective immunity in pigs. The resulting quantitative model, predicting viable cyst counts based on dose and age, offers valuable insights for integrating immunity dynamics into transmission models, supporting the development of more effective strategies for controlling T. solium.
{"title":"Immunity against reinfection in pigs following Taenia solium infection and a quantitative dose–response model","authors":"Eloy Gonzales-Gustavson , Francesco Pizzitutti , Gabrielle Bonnet , Claudio Muro , Ricardo Gamboa , Javier A. Bustos , Sarah Gabriël , William K. Pan , Héctor H. Garcia , Seth O'Neal , for the CWGP","doi":"10.1016/j.ijpara.2025.08.010","DOIUrl":"10.1016/j.ijpara.2025.08.010","url":null,"abstract":"<div><div><em>Taenia solium</em> is a zoonotic parasite causing significant health and economic burdens, with complex transmission dynamics that demand improved control strategies. This study examines how infection and reinfection affect cyst development in pigs and how acquired immunity constrains parasite burden. A total of 116 pigs were purchased from commercial farms in northern Peru and housed under controlled conditions. Of these, 110 pigs were allocated to 18 experimental groups to evaluate the impact of single and repeated infections with varying doses of <em>T. solium</em> eggs and to model the number of live cysts produced based on dose and age at infection. Gravid proglottids collected from human cases were used to prepare viable egg pools. Infections were administered orally via esophageal catheterization, and pigs were necropsied 10 weeks after the final infection to quantify cyst burden. A negative binomial regression model assessed the influence of infection dose, prior infection, age, and other factors. No significant differences in cyst counts were found between singly infected and reinfected pigs, regardless of initial or reinfection doses, highlighting that infection induces strong acquired immunity that prevents subsequent infections. A dose–response analysis indicated that cyst burden follows a power relationship with egg dose. Integrating data from both single and reinfected pigs into a unified model improved prediction precision. Furthermore, incorporating age at infection allowed us to model the combined effects of acquired and innate immunity, reflecting changes in susceptibility over time. These findings demonstrate that a single exposure to <em>T. solium</em> eggs can generate robust protective immunity in pigs. The resulting quantitative model, predicting viable cyst counts based on dose and age, offers valuable insights for integrating immunity dynamics into transmission models, supporting the development of more effective strategies for controlling <em>T. solium.</em></div></div>","PeriodicalId":13725,"journal":{"name":"International journal for parasitology","volume":"56 2","pages":"Article 104722"},"PeriodicalIF":3.2,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144953021","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-01DOI: 10.1016/j.ijpara.2025.08.005
Vahid Sepahvand, Miles D. Lamare, Ceridwen I. Fraser
Large ectoparasitic copepods, nearly as long as the length of their host, are often found on Antarctic fish, yet little is known about their biology. In this study, we investigated the genetic structure and host-parasite relationships in Macrourus whitsoni, a deep-sea fish, and its copepod ectoparasite, Lophoura szidati, using 10,569 biallelic SNPs collected from 38 copepods and 5,009 biallelic SNPs from 35 fish individuals across three populations in the Ross Sea, Antarctica. The Fst, DAPC, and admixture analyses revealed distinct genetic patterns between the two species. For M. whitsoni, our results demonstrated low to moderate genetic differentiation among populations, while L. szidati exhibited strong population structure. Nucleotide diversity (π) differed significantly among both fish host and copepod parasite populations, reflecting contrasting patterns of genetic variation. Tajima’s D values were consistently negative in both hosts and parasites, indicating an excess of rare alleles, which suggests recent population expansion or purifying selection. Analysis of host-parasite coevolution revealed both congruent and discordant patterns. While some host-parasite pairs showed strong congruence, suggesting possible specialized coevolutionary relationships, other associations showed signs of discordance, suggesting host-switching events or ecological divergence. The contrasting genetic patterns and coevolutionary dynamics in our study open new directions for future research to show how life history traits, dispersal capacity, and environmental factors influence the biology and evolution of host-parasite species in the unique and extreme Ross Sea.
{"title":"Comparative population genetics of the Antarctic grenadier fish (Macrourus whitsoni) and its parasitic copepod (Lophoura szidati)","authors":"Vahid Sepahvand, Miles D. Lamare, Ceridwen I. Fraser","doi":"10.1016/j.ijpara.2025.08.005","DOIUrl":"10.1016/j.ijpara.2025.08.005","url":null,"abstract":"<div><div>Large ectoparasitic copepods, nearly as long as the length of their host, are often found on Antarctic fish, yet little is known about their biology. In this study, we investigated the genetic structure and host-parasite relationships in <em>Macrourus whitsoni</em>, a deep-sea fish, and its copepod ectoparasite, <em>Lophoura szidati</em>, using 10,569 biallelic SNPs collected from 38 copepods and 5,009 biallelic SNPs from 35 fish individuals across three populations in the Ross Sea, Antarctica. The Fst, DAPC, and admixture analyses revealed distinct genetic patterns between the two species. For <em>M. whitsoni</em>, our results demonstrated low to moderate genetic differentiation among populations, while <em>L. szidati</em> exhibited strong population structure. Nucleotide diversity (<em>π</em>) differed significantly among both fish host and copepod parasite populations, reflecting contrasting patterns of genetic variation. Tajima’s <em>D</em> values were consistently negative in both hosts and parasites, indicating an excess of rare alleles, which suggests recent population expansion or purifying selection. Analysis of host-parasite coevolution revealed both congruent and discordant patterns. While some host-parasite pairs showed strong congruence, suggesting possible specialized coevolutionary relationships, other associations showed signs of discordance, suggesting host-switching events or ecological divergence. The contrasting genetic patterns and coevolutionary dynamics in our study open new directions for future research to show how life history traits, dispersal capacity, and environmental factors influence the biology and evolution of host-parasite species in the unique and extreme Ross Sea.</div></div>","PeriodicalId":13725,"journal":{"name":"International journal for parasitology","volume":"56 2","pages":"Article 104717"},"PeriodicalIF":3.2,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144953026","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-01DOI: 10.1016/j.ijpara.2025.08.002
Shi-Chen Xie , Yi-Han Lv , Meng Wang , Xiao-Nan Zheng , Jin-Lei Wang , Bao-Quan Fu , Xing-Quan Zhu
Toxoplasma gondii is a zoonotic protozoan pathogen capable of infecting humans and nearly all warm-blooded animals, and causing substantial economic losses to the livestock industry. Developing an effective vaccine against T. gondii remains an urgent priority for controlling the spread of this zoonotic parasite. In this study, we evaluated the protective efficacy of a live-attenuated T. gondii PruΔpp2a-c mutant in both mice and cats. Immunization with PruΔpp2a-c elicited strong cellular (IL-2, IL-4, IL-10, IL-12, and IFN-γ) and humoral (IgG, IgG1, and IgG2a) immune responses in mice, conferring protection against lethal challenge with various T. gondii strains, including highly virulent Type I (RH), mildly virulent ToxoDB#9 (PYS), and less virulent Type II (Pru) strains. While partial protection was observed against virulent strains, almost complete immune protection was achieved against both acute and chronic infections by the less virulent Pru strain, along with a significant reduction in brain cyst burden (P < 0.001). Notably, vaccination of cats with PruΔpp2a-c induced high antibody titers and led to a 94.5 % reduction in fecal oocyst shedding (P < 0.001) following homologous challenge, thereby significantly decreasing the potential for environmental transmission. These findings demonstrate that PruΔpp2a-c provides strong cross-protection against various T. gondii strains and substantially limits oocyst shedding. The dual efficacy observed in both intermediate and definitive hosts highlights PruΔpp2a-c as a promising live-attenuated vaccine candidate for preventing transmission of T. gondii by cats.
{"title":"Live-attenuated Toxoplasma gondii PruΔpp2a-c mutant elicits protective immunity against toxoplasmosis in mice and cats","authors":"Shi-Chen Xie , Yi-Han Lv , Meng Wang , Xiao-Nan Zheng , Jin-Lei Wang , Bao-Quan Fu , Xing-Quan Zhu","doi":"10.1016/j.ijpara.2025.08.002","DOIUrl":"10.1016/j.ijpara.2025.08.002","url":null,"abstract":"<div><div><em>Toxoplasma gondii</em> is a zoonotic protozoan pathogen capable of infecting humans and nearly all warm-blooded animals, and causing substantial economic losses to the livestock industry. Developing an effective vaccine against <em>T. gondii</em> remains an urgent priority for controlling the spread of this zoonotic parasite. In this study, we evaluated the protective efficacy of a live-attenuated <em>T. gondii</em> PruΔ<em>pp2a-c</em> mutant in both mice and cats. Immunization with PruΔ<em>pp2a-c</em> elicited strong cellular (IL-2, IL-4, IL-10, IL-12, and IFN-γ) and humoral (IgG, IgG1, and IgG2a) immune responses in mice, conferring protection against lethal challenge with various <em>T. gondii</em> strains, including highly virulent Type I (RH), mildly virulent ToxoDB#9 (PYS), and less virulent Type II (Pru) strains. While partial protection was observed against virulent strains, almost complete immune protection was achieved against both acute and chronic infections by the less virulent Pru strain, along with a significant reduction in brain cyst burden (<em>P</em> < 0.001). Notably, vaccination of cats with PruΔ<em>pp2a-c</em> induced high antibody titers and led to a 94.5 % reduction in fecal oocyst shedding (<em>P</em> < 0.001) following homologous challenge, thereby significantly decreasing the potential for environmental transmission. These findings demonstrate that PruΔ<em>pp2a-c</em> provides strong cross-protection against various <em>T. gondii</em> strains and substantially limits oocyst shedding. The dual efficacy observed in both intermediate and definitive hosts highlights PruΔ<em>pp2a-c</em> as a promising live-attenuated vaccine candidate for preventing transmission of <em>T. gondii</em> by cats.</div></div>","PeriodicalId":13725,"journal":{"name":"International journal for parasitology","volume":"56 2","pages":"Article 104714"},"PeriodicalIF":3.2,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144812013","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-01DOI: 10.1016/j.ijpara.2025.07.004
Tanja Himmel , Josef Harl , Julia Matt , Nora Nedorost , Mélanie Duc , Mélanie Tchoumbou , Tatjana Iezhova , Gediminas Valkiūnas , Herbert Weissenböck
During exo-erythrocytic merogony, avian Haemoproteus parasites (Apicomplexa, Haemosporida) develop distinct tissue stages: small meronts and large megalomeronts. Recent molecular studies suggest that Haemoproteus species develop either of the two morphotypes in naturally infected birds but earlier research indicates that certain species form both depending on the replicating cycle. Because data on tissue stages are limited to a few described species, patterns and mechanisms of (megalo-)merogony are unclear but required to better understand pathologies during haemoproteosis.
In this study, we aimed to characterize exo-erythrocytic stages of Haemoproteus species in naturally infected flycatchers (Muscicapidae). Tissue samples of eight Ficedula hypoleuca and two Ficedula parva positive by PCR and blood smear microscopy were subjected to histology and in situ hybridization applying Haemoproteus lineage-specific probes. Additionally, laser capture microdissection was performed to enable molecular identification of individual tissue stages. A phylogenetic analysis based on the parasites’ cytochrome b gene (886 bp) was performed to explore the relationship of meront- and megalomeront-forming species within the genus Haemoproteus.
In F. hypoleuca, we found meronts and megalomeronts, and molecular data indicate that both belong to Haemoproteus balmorali, suggesting phenotypic variation of this parasite. Phylogenetically, H. balmorali was closely related to Haemoproteus attenuatus, which develops similar meronts but no megalomeronts, suggesting varying phenotypic variation among closely related species. In F. parva, we detected megalomeronts and gametocytes of Haemoproteus majoris hPHSIB1, presenting the first record in that host. By contrast, in F. hypoleuca showing high H. pallidus gametocytaemia, no exo-erythrocytic stages were found, implying that merogony was completed and not coinciding with gametocytaemia. These results demonstrate that exo-erythrocytic development varies considerably between species and patterns of tissue merogony may not be generalized at genus level. Furthermore, we report significant nuclear hypertrophy of the host cell in Haemoproteus megalomeronts, a feature formerly considered unique to Leucocytozoon, challenging it’s use for genus identification.
{"title":"Tissue stages of Haemoproteus parasites (Haemosporida, Apicomplexa) in Ficedula flycatchers with evidence for phenotypic variation in Haemoproteus balmorali and implications for haemosporidian taxonomy","authors":"Tanja Himmel , Josef Harl , Julia Matt , Nora Nedorost , Mélanie Duc , Mélanie Tchoumbou , Tatjana Iezhova , Gediminas Valkiūnas , Herbert Weissenböck","doi":"10.1016/j.ijpara.2025.07.004","DOIUrl":"10.1016/j.ijpara.2025.07.004","url":null,"abstract":"<div><div>During exo-erythrocytic merogony, avian <em>Haemoproteus</em> parasites (Apicomplexa, Haemosporida) develop distinct tissue stages: small meronts and large megalomeronts. Recent molecular studies suggest that <em>Haemoproteus</em> species develop either of the two morphotypes in naturally infected birds but earlier research indicates that certain species form both depending on the replicating cycle. Because data on tissue stages are limited to a few described species, patterns and mechanisms of (megalo-)merogony are unclear but required to better understand pathologies during haemoproteosis.</div><div>In this study, we aimed to characterize exo-erythrocytic stages of <em>Haemoproteus</em> species in naturally infected flycatchers (Muscicapidae). Tissue samples of eight <em>Ficedula hypoleuca</em> and two <em>Ficedula parva</em> positive by PCR and blood smear microscopy were subjected to histology and in situ hybridization applying <em>Haemoproteus</em> lineage-specific probes. Additionally, laser capture microdissection was performed to enable molecular identification of individual tissue stages. A phylogenetic analysis based on the parasites’ cytochrome <em>b</em> gene (886 bp) was performed to explore the relationship of meront- and megalomeront-forming species within the genus <em>Haemoproteus</em>.</div><div>In <em>F. hypoleuca</em>, we found meronts and megalomeronts, and molecular data indicate that both belong to <em>Haemoproteus balmorali</em>, suggesting phenotypic variation of this parasite. Phylogenetically, <em>H. balmorali</em> was closely related to <em>Haemoproteus attenuatus</em>, which develops similar meronts but no megalomeronts, suggesting varying phenotypic variation among closely related species. In <em>F. parva</em>, we detected megalomeronts and gametocytes of <em>Haemoproteus majoris</em> hPHSIB1, presenting the first record in that host. By contrast, in <em>F. hypoleuca</em> showing high <em>H. pallidus</em> gametocytaemia, no exo-erythrocytic stages were found, implying that merogony was completed and not coinciding with gametocytaemia. These results demonstrate that exo-erythrocytic development varies considerably between species and patterns of tissue merogony may not be generalized at genus level. Furthermore, we report significant nuclear hypertrophy of the host cell in <em>Haemoproteus</em> megalomeronts, a feature formerly considered unique to <em>Leucocytozoon</em>, challenging it’s use for genus identification.</div></div>","PeriodicalId":13725,"journal":{"name":"International journal for parasitology","volume":"56 2","pages":"Article 104711"},"PeriodicalIF":3.2,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144764792","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-01DOI: 10.1016/j.ijpara.2025.08.007
Salvatore Capuozzo , Maria Paola Maurelli , Stefano Marrone , Biase Celano , Giuseppe Martone , Paola Vitiello , Ines Hammami , Antonio Bosco , Lavinia Ciuca , Giuseppe Cringoli , Carlo Sansone , Laura Rinaldi
Fasciola hepatica and Calicophoron daubneyi are trematodes with significant health and economic impacts on ruminant livestock farms. An effective and reliable diagnosis is essential to control their spread. To improve copromicroscopic diagnosis, the Kubic FLOTAC Microscope (KFM), a portable digital microscope, was designed for both laboratory and field use. It is based on the use of FLOTAC/Mini-FLOTAC techniques and combines their high sensitivity, accuracy and precision with a reliable system based on an Artificial Intelligence (AI) predictive model. It features automated parasite egg detection, powered by an integrated battery, a web interface for microscope control, and a dedicated AI server for image analysis. In this study, the system was optimized to better discriminate between the eggs of these two parasites through additional processing steps and a robust detection model. Two protocols, egg-spiked samples and naturally infected samples, were used to simulate different sample conditions, creating a dataset for model training and evaluation. A second dataset of field samples, with egg counts verified by optical microscopy, was used to assess performance. The detection performance during the evaluation of samples from both protocols was found to be satisfactory. Specifically, the average fecal egg count, obtained through the clinical report generated by the KFM system, exhibited a mean absolute error of only 8 eggs per sample. This result demonstrates that the KFM is a valuable tool for parasitological diagnosis that supports the livestock industry.
{"title":"A dedicated deep learning workflow for automatic Fasciola hepatica and Calicophoron daubneyi egg detection using the Kubic FLOTAC microscope","authors":"Salvatore Capuozzo , Maria Paola Maurelli , Stefano Marrone , Biase Celano , Giuseppe Martone , Paola Vitiello , Ines Hammami , Antonio Bosco , Lavinia Ciuca , Giuseppe Cringoli , Carlo Sansone , Laura Rinaldi","doi":"10.1016/j.ijpara.2025.08.007","DOIUrl":"10.1016/j.ijpara.2025.08.007","url":null,"abstract":"<div><div><em>Fasciola hepatica</em> and <em>Calicophoron daubneyi</em> are trematodes with significant health and economic impacts on ruminant livestock farms. An effective and reliable diagnosis is essential to control their spread. To improve copromicroscopic diagnosis, the Kubic FLOTAC Microscope (KFM), a portable digital microscope, was designed for both laboratory and field use. It is based on the use of FLOTAC/Mini-FLOTAC techniques and combines their high sensitivity, accuracy and precision with a reliable system based on an Artificial Intelligence (AI) predictive model. It features automated parasite egg detection, powered by an integrated battery, a web interface for microscope control, and a dedicated AI server for image analysis. In this study, the system was optimized to better discriminate between the eggs of these two parasites through additional processing steps and a robust detection model. Two protocols, egg-spiked samples and naturally infected samples, were used to simulate different sample conditions, creating a dataset for model training and evaluation. A second dataset of field samples, with egg counts verified by optical microscopy, was used to assess performance. The detection performance during the evaluation of samples from both protocols was found to be satisfactory. Specifically, the average fecal egg count, obtained through the clinical report generated by the KFM system, exhibited a mean absolute error of only 8 eggs per sample. This result demonstrates that the KFM is a valuable tool for parasitological diagnosis that supports the livestock industry.</div></div>","PeriodicalId":13725,"journal":{"name":"International journal for parasitology","volume":"56 2","pages":"Article 104719"},"PeriodicalIF":3.2,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144953070","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-01DOI: 10.1016/j.ijpara.2025.08.006
Brooke A. McPhail, Sara Tomusiak, Hannah Veinot, Neill Dodds, Patrick C. Hanington
Snail hosts play a central role in structuring trematode communities. To test how snail hosts shape parasite diversity in central Alberta, we built upon a previous snail–trematode survey conducted at six lakes in central Alberta from 2013 to 2015 that uncovered 79 trematode species. However, analyses suggested that additional species remained to be uncovered. To build on this baseline, we conducted further snail–trematode collections from 2019 to 2022 at eight reclaimed wetland sites in various stages of reclamation, along with one established lake in Alberta. Across the nine sites, we collected 22,397 snails, of which 1981 were infected with digenetic trematodes. We also documented broader biodiversity at these sites using traditional survey techniques. Through DNA barcoding, we identified 74 trematode species infecting five snail species. Among these were 23 trematode species not previously reported in central Alberta and nine provisionally-named lineages with no matches to species in publicly available databases. In addition, we observed several previously unreported snail-trematode interactions. While trematode richness did not vary significantly with the wetland reclamation stage, host identity did influence richness: Physa gyrina hosted significantly more trematode species than Planorbella trivolvis. When combined with data from the earlier survey, sample completeness analyses indicate that we captured 100 % of the dominant species and 99 % of the typical species, but only 63 % of the overall species diversity in central Alberta. These findings underscore that trematode diversity in central Alberta remains incompletely characterized and highlight the continued value of long-term and host-inclusive sampling efforts.
{"title":"Reclaimed wetlands support rich trematode and host diversity: findings from a four-year survey","authors":"Brooke A. McPhail, Sara Tomusiak, Hannah Veinot, Neill Dodds, Patrick C. Hanington","doi":"10.1016/j.ijpara.2025.08.006","DOIUrl":"10.1016/j.ijpara.2025.08.006","url":null,"abstract":"<div><div>Snail hosts play a central role in structuring trematode communities. To test how snail hosts shape parasite diversity in central Alberta, we built upon a previous snail–trematode survey conducted at six lakes in central Alberta from 2013 to 2015 that uncovered 79 trematode species. However, analyses suggested that additional species remained to be uncovered. To build on this baseline, we conducted further snail–trematode collections from 2019 to 2022 at eight reclaimed wetland sites in various stages of reclamation, along with one established lake in Alberta. Across the nine sites, we collected 22,397 snails, of which 1981 were infected with digenetic trematodes. We also documented broader biodiversity at these sites using traditional survey techniques. Through DNA barcoding, we identified 74 trematode species infecting five snail species. Among these were 23 trematode species not previously reported in central Alberta and nine provisionally-named lineages with no matches to species in publicly available databases. In addition, we observed several previously unreported snail-trematode interactions. While trematode richness did not vary significantly with the wetland reclamation stage, host identity did influence richness: Physa gyrina hosted significantly more trematode species than Planorbella trivolvis. When combined with data from the earlier survey, sample completeness analyses indicate that we captured 100 % of the dominant species and 99 % of the typical species, but only 63 % of the overall species diversity in central Alberta. These findings underscore that trematode diversity in central Alberta remains incompletely characterized and highlight the continued value of long-term and host-inclusive sampling efforts.</div></div>","PeriodicalId":13725,"journal":{"name":"International journal for parasitology","volume":"56 2","pages":"Article 104718"},"PeriodicalIF":3.2,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144953075","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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