A delayed diagnosis of fascioliasis: The importance of appropriate fecal diagnostic method

Fascioliasis, a zoonotic helminthiasis, occurs sporadically in Japan. In this report, we describe a case of fascioliasis that was initially difficult to diagnose because the fecal examination method was negative for the Fasciola sp. eggs. A 64-year-old man living in Shimonoseki City, Japan, presented with fatigue and anorexia. Laboratory tests showed hepatic dysfunction and eosinophilia. Abdominal dynamic contrast-enhanced computed tomography and magnetic resonance cholangiopancreatography suggested intrahepatic biliary cysts. Thereafter, fever and night sweats persisted, and positron emission tomography and biopsy of the porta hepatis lymph node were performed on suspicion of malignancy. However, histopathological diagnosis found non-specific inflammation. As fascioliasis was suspected due to eosinophilia and the multiple hepatic masses, fecal egg examination was performed by an external private laboratory, which adopted the flotation method and reported the absence of parasite eggs. However, fecal examination was retried in our laboratory using the formalin-ether concentration method, and we detected Fasciola sp. eggs. This case suggests that misdiagnosis may occur depending on the fecal examination method; thus, it is necessary to choose a suitable method for certain parasite species.

Syntenic relationship of chromosomes in Strongyloides species and Rhabditophanes diutinus based on the chromosome-level genome assemblies

The Strongyloides clade, to which the parasitic nematode genus Strongyloides belongs, contains taxa with diverse lifestyles, ranging from free-living to obligate vertebrate parasites. Reproductive strategies are also diverse in this group of nematodes, employing not only sexual reproduction but also parthenogenesis, making it an attractive group to study genome adaptation to specific conditions. An in-depth understanding of genome evolution, however, has been hampered by fragmented genome assemblies. In this study, we generated chromosome-level genome assemblies for two Strongyloides species and the outgroup species Rhabditophanes diutinus using long-read sequencing and high-throughput chromosome conformation capture (Hi-C). Our synteny analyses revealed a clearer picture of chromosome evolution in this group, suggesting that a functional sex chromosome has been maintained throughout the group. We further investigated sex chromosome dynamics in the lifecycle of Strongyloides ratti and found that bivalent formation in oocytes appears to be important for male production in the mitotic parthenogenesis. This article is part of the Theo Murphy meeting issue 'Strongyloides: omics to worm-free populations'.

Pneumothorax with Eosinophilia is an Important Diagnostic Clue for Distinguishing Paragonimiasis from Chronic Eosinophilic Pneumonia: A Case Report

The Paragonimus westermani infection is a parasitic foodborne infection that induces systemic symptoms with eosinophilia in humans. Here, we described pneumothorax in addition to pulmonary opacities with eosinophilia in a man with a positive P. westermani serology. He was misdiagnosed with chronic eosinophilic pneumonia (CEP) during the initial phase. Paragonimiasis can share similar clinical findings with CEP in cases where the worm is confined to the lungs. The findings of the current study suggest that paragonimiasis and CEP can be distinguished from each other by the presence of various symptoms. Notably, eosinophilia with pneumothorax should be an important diagnostic factor for paragonimiasis.

Population genetics study of Strongyloides fuelleborni and phylogenetic considerations on primate-infecting species of Strongyloides based on their mitochondrial genome sequences

Strongyloides is a genus of parasitic nematodes of vertebrates comprising approximately 50 documented species, each with various host ranges. Among these, three species (S. stercoralis, S. fuelleborni, and S. cebus) are known to infect primate hosts. S. fuelleborni typically infects non-human primates in the Old World. To complement the existing information on the global genetic structure of this species, we conducted a genotyping study of S. fuelleborni samples collected from rhesus macaques in Myanmar, Japanese macaques in Japan, and some zoo-kept primates. This study identified a novel haplotype group in isolates from the Myanmar rhesus macaques. Subsequently, we obtained the complete or nearly complete mitochondrial genome sequences of S. fuelleborni, S. cebus (Strongyloides of New World monkeys), and S. vituli (Strongyloides of cattle). Phylogenetic analysis based on concatenated mitochondrial protein sequences of various Strongyloides species indicated a close relationship between S. fuelleborni, S. vituli and S. papillosus (Strongyloides in sheep and cattle). S. cebus is quite distantly related to both S. fuelleborni and S. stercoralis, which led to the hypothesis that the three primate Strongyloides species evolved independently as parasites of primates.

Preliminary evaluation of a flow cytometric assay with microsphere controls for the detection of platelet-bound antibodies in canine immune thrombocytopenia

BACKGROUND

Canine immune thrombocytopenia (ITP) ranges from a mild to severe bleeding disorder, and platelet counts do not reliably predict clinical disease course. The detection of platelet autoantibodies may further define the disease phenotype, but variability in assay configurations and a lack of well-characterized controls limit the diagnostic utility of anti-platelet antibody assays.

OBJECTIVES

We aimed to develop control reagents to facilitate the characterization of canine platelet surface-associated immunoglobulin (PSAIg) in flow cytometric assays.

METHODS

Silica microspheres were coated with canine IgG and IgM to assess the reactivity of goat and rabbit origin anti-canine immunoglobulin reagents. They were also used as positive controls in the PSAIg assay. Preliminary assay evaluation and determination of sample stability used PRP isolated from seven healthy dogs and 26 dogs newly diagnosed with thrombocytopenia.

RESULTS

Blood sample stability was established for up to a 48-hour storage time. The conjugated positive control microspheres demonstrated stable fluorescent labeling over a 2-year observation period. Rabbit and goat origin anti-dog IgM fluorescent antibody labels reacted nonspecifically with canine IgG. Rabbit origin anti-dog IgG antibody demonstrated greater class specificity for canine IgG than a goat origin antibody. Thrombocytopenic dogs had a broad range of membrane-bound immunoglobulin. Median PSAIgG for dogs with primary or secondary ITP (18.4%, 34.1%, respectively) were significantly higher than controls (3.8%, P < .05).

CONCLUSIONS

The described assay reagents and procedures provide positive controls and allow consistent thresholding to define a positive test result, suitable for any flow cytometer. A rabbit anti-dog IgG fluorescent label demonstrated specificity for canine IgG and was useful for the detection of PSAIgG in thrombocytopenic dogs.

Clinico-radiologic Characteristics of Pulmonary Visceral Larva Migrans Caused by Ascaris suum

Objective Visceral larva migrans (VLM) caused by Ascaris suum is a major health problem in pig farming regions. The clinical characteristics of pulmonary VLM caused by A. suum, however, are unclear. We assessed the clinico-radiologic features of this disease. Methods Medical records, including the results of chest radiography and high-resolution computed tomography (HRCT), were retrospectively reviewed from January 2000 through June 2019, at the University of Miyazaki Hospital and Kyoritsuiin Hospital in Miyazaki Prefecture, Japan. Results Seven patients with VLM caused by A. suum were identified. All seven patients had a unique habit of consuming raw foods, such as organic vegetables, chicken, turkey, wild boar, and venison. All but one patient, who had eosinophilic pneumonia with a fever and severe fatigue, had only mild or no respiratory symptoms. All 7 patients had remarkable eosinophilia (median, 1,960/μL) and high serum IgE levels (median, 1,346 IU/mL). Chest HRCT revealed multiple nodules and multiple nodular ground-glass opacities in 57% and 29% of the patients, respectively. The pulmonary lesions were located predominantly in subpleural areas. All seven patients were treated with albendazole, which led to improvement within two to three months. Neither eggs nor parasites were detected in the feces or sputum of any patient. Conclusion Consumption of raw organic vegetables or raw meat is a possible route of A. suum infection. Infected patients exhibit mild respiratory symptoms, and multiple nodules with a halo in the subpleural area are a common finding on chest HRCT. Treatment with albendazole was effective in these cases.

First demonstration of Strongyloides parasite from an imported pet meerkat - Possibly a novel species in the stercoralis/procyonis group

Strongyloides is a genus of parasitic nematodes of vertebrates that contains over 50 species, each with a variable host range. A recent molecular phylogenetic analysis on this genus showed that Strongyloides spp. from various carnivore hosts form a strongly supported clade together with Strongyloides stercoralis, a major pathogen of humans and dogs (named the "stercoralis/procyonis group"). In the present study, we obtained DNA sequencing data of Strongyloides sp. isolated from an imported meerkat (Suricata suricatta). Based on the phylogenetic analysis, we considered this a new member of the stercoralis/procyonis group. This study represents the first isolation and molecular characterization of a Strongyloides species from hosts belonging to the family Herpestidae (mongooses and meerkat). However, whether the meerkat serves as a natural host of this Strongyloides species remains to be investigated.

Potential of antibody test using Schistosoma mansoni recombinant serpin and RP26 to detect light-intensity infections in endemic areas

Schistosomiasis remains a worldwide public health problem, especially in sub-Saharan Africa. The World Health Organization targets the goal for its elimination as a public health problem in the 2030 Neglected Tropical Diseases (NTDs) Roadmap. Concerted action and agile responses to challenges will be necessary to achieve the targets. Better diagnostic tests can accelerate progress towards the elimination by monitoring disease trends and evaluating the effectiveness of interventions; however, current examinations such as Kato-Katz technique are of limited power to detect light-intensity infections. The point-of-care circulating cathodic antigen (POC-CCA) test shows a higher sensitivity compared to the reference standard, Kato-Katz technique, but it still lacks sufficient sensitivity with low infection intensity. In this study, we examined antibody reactions against recombinant protein antigens; Schistosoma mansoni serine protease-inhibitor (SmSerpin) and RP26, by enzyme-linked immunosorbent assay (ELISA) in plasma samples with light-intensity infection. The sensitivity using the cocktail antigen of recombinant SmSerpin and RP26 showed 83.7%. The sensitivity using S. mansoni soluble egg antigen (SmSEA) was 90.8%, but it showed poor specificity (29.7%), while the cocktail antigen presented improved specificity (61.4%). We conclude that antibody detection to the SmSerpin and RP26 protein antigens is effective to detect S. mansoni light-intensity infections. Our study indicates the potential of detecting antibody against recombinant protein antigens to monitor the transmission of schistosomiasis in low endemicity contexts.

Primaquine plus clindamycin as a promising salvage therapy for Pneumocystis jirovecii pneumonia: A retrospective analysis in Japanese patients

Treatment of intractable Pneumocystis jirovecii pneumonia (PCP) patients with primaquine (PQ) in combination with clindamycin (CLDM) was conducted by the Research Group on Chemotherapy of Tropical Diseases (RG-CTD), as a kind of compassionate use. Primaquine was not nationally licensed at the time but imported by RG-CTD for the use in a clinical research to investigate safety and efficacy in malaria treatment. Eighteen Japanese adult patients thus treated were analyzed. Prior to the treatment with PQ-CLDM, most of the patients had been treated with trimethoprim-sulfamethoxazole first, all of which being followed by pentamidine and/or atovaquone treatment. This combination regimen of PQ-CLDM was effective in 16 (89%) patients and developed adverse events (AEs) in five (28%) patients. AEs included skin lesions, methemoglobinemia, and hepatic dysfunction, though none of them were serious. As a second-line or salvage treatment for PCP, PQ-CLDM appears to be a better option than pentamidine or atovaquone. Currently in Japan, both PQ and CLDM are licensed drugs but neither of them is approved for treatment of PCP. Considering the potentially fatal nature of PCP, approval of PQ-CLDM for treating this illness should be urged.

Application of a real-time PCR assay for the detection of Ascaris suum DNA in the liver of experimentally infected chickens

This study aimed to evaluate the sampling method for the detection of Ascaris suum larval DNA in chicken livers using real-time PCR. Chickens were inoculated with A. suum eggs of a single dose (Group A) or repeatedly low doses (Group B). White spots (WSs) were continuously observed on liver from day 3 after the last infection in Group B and day 14 in Group A. In Group A, larval DNA was detected in WS lesions (78.6%) at a significantly higher rate than in the remaining tissue samples (31.3%). In conclusion, applying WS lesions to the assay improved the detection rate of A. suum DNA in chicken livers, especially in the case of a single infection.

An outbreak of Paragonimus westermani infection among Cambodian technical intern trainees in Japan, exhibiting various extrapulmonary lesions

We encountered an outbreak of paragonimiasis among Cambodian technical intern trainees (TITs) at a food-processing factory in Fukuoka, Japan. The patients were 20-28 years old, seven females and two males, who had been in Japan for one to four years. All of them had consumed raw or undercooked Japanese mitten crab they purchased at a local grocery store near their training place. CT images showed multiple lesions not only in the lungs but in the extrapulmonary organs as well, such as subcutaneous tissues, abdominal muscles, and mesentery, in most of the patients. Their medical records indicated that all of them acquired infection in Japan, not in Cambodia. Diagnosis was made serologically and the patients were treated with praziquantel successfully. Foreign workers and TITs are increasing in Japan so rapidly, that food borne-infections, including paragonimiasis, should be considered in people from developing countries who have exotic dietary habits.

Meningitis patients with Angiostrongylus cantonensis may present without eosinophilia in the cerebrospinal fluid in northern Vietnam

Background

Eosinophilic meningitis (EM) is a rare clinical syndrome caused by both infectious and noninfectious diseases. In tropical pacific countries, Angiostrongylus cantonensis is the most common cause. However, the EM definition varies in the literature, and its relation to parasitic meningitis (PM) remains unclear.

Methodology/Principal findings

Adult and adolescent patients of 13 years old or above with suspected central nervous system (CNS) infections with abnormal CSF findings were prospectively enrolled at a tertiary referral hospital in Hanoi, Vietnam from June 2012 to May 2014. Patients with EM or suspected PM (EM/PM) were defined by the presence of either ≥10% eosinophils or an absolute eosinophil cell counts of ≥10/mm³ in the CSF or blood eosinophilia (>16% of WBCs) without CSF eosinophils. In total 679 patients were enrolled: 7 (1.03%) had ≥10% CSF eosinophilia, 20 (2.95%) had ≥10/mm³ CSF eosinophilia, and 7 (1.03%) had >16% blood eosinophilia. The patients with ≥10% CSF eosinophilia were significantly younger (p = 0.017), had a lower body temperature (p = 0.036) than patients with ≥10/mm³ CSF eosinophilia among whom bacterial pathogens were detected in 72.2% (13/18) of those who were tested by culture and/or PCR. In contrast, the characteristics of the patients with >16% blood eosinophilia resembled those of patients with ≥10% CSF eosinophilia. We further conducted serological tests and real-time PCR to identify A. cantonensis. Serology or real-time PCR was positive in 3 (42.8%) patients with ≥10% CSF eosinophilia and 6 (85.7%) patients with >16% blood eosinophilia without CSF eosinophils but none of patients with ≥10/mm³ CSF eosinophilia.

Conclusions

The etiology of PM in northern Vietnam is A. cantonensis. The eosinophil percentage is a more reliable predictor of parasitic EM than absolute eosinophil count in the CSF. Patients with PM may present with a high percentage of eosinophils in the peripheral blood but not in the CSF.

Eosinophilic meningitis (EM) is a rare meningitis accompanied by eosinophils in the CSF and caused by multiple etiologies. Angiostrongylus cantonensis, which is a rat lungworm parasite, is the most common cause in tropical Asia. Previous papers have defined EM as CSF eosinophils ≥10% or CSF eosinophils ≥10/mm³. However, the relationship of EM to parasitic meningitis (PM) remains unclear. This prospective study enrolled 679 patients with suspected CNS infection who were admitted to a tertiary referral hospital in Hanoi, Vietnam from June 2012 to May 2014. The characteristics of patients with ≥10% CSF eosinophilia resembled those of patients with >16% blood eosinophilia without CSF eosinophils, whereas those of patients with ≥10/mm³ CSF eosinophilia were comparable with those of patients with typical bacterial meningitis. Serology or real-time PCR for A. cantonensis was positive in 3 out of 7 patients with ≥10% CSF eosinophilia and 6 out of 7 patients with > 16% blood eosinophilia without CSF eosinophils but none of patients with ≥10/mm³ CSF eosinophilia. The percentage, in contrast to the absolute eosinophil count in CSF, is reliable for predicting parasitic EM. Patients with PM may present with eosinophilia in the peripheral blood but not in the CSF.

Seroprevalence of toxoplasmosis among reproductive-aged women in Myanmar and evaluation of luciferase immunoprecipitation system assay

BACKGROUNDS

Primary infection with Toxoplasma gondii during pregnancy can pose serious health problems for the fetus. However, the epidemiological status of toxoplasmosis among reproductive-aged population in Myanmar is largely unknown. Although luciferase immunoprecipitation system (LIPS) assays for serodiagnosis of toxoplasmosis was developed mostly using mouse infection model, had not been tested by using field-derived human samples.

METHODS

A total of 251 serum samples were collected from reproductive-aged women, residing in Shwegyin township, Bago region, Myanmar and analyzed with a commercial ELISA kit, as well as in-house LIPS assays.

RESULTS

The overall seroprevalence for Toxoplasma gondii infection by the commercial ELISA was 11.5%. No clear risk factor was identified except for being in the younger age group (15-30 years old). Overall, LIPS assays showed low sensitivity when the commercial ELSA was used as a reference test.

CONCLUSION

We identified the epidemiological situation of toxoplasmosis in some rural communities in Myanmar. The data obtained here will serve as a primary information for the effort to reduce toxoplasmosis in this region. Although looked promising in the previous experiments with mouse infection model, we found that the reported LIPS procedures need further improvements to increase the sensitivities.

Contribution of peptidyl prolyl isomerase (Pin1) to development of pulmonary hypertension via pulmonary vascular endothelial cell dysfunction

Background

Endothelial dysfunction is thought to be a major contributor to overall pathogenesis of vasculopathy seen in pulmonary hypertension (PH), which is manifested by the impaired release of nitric oxide (NO) generated through endothelial nitric oxide synthase (eNOS) in endothelial cells. Activation of human eNOS is regulated by phosphorylation at multiple sites including Thr33 and Ser114, which residues are followed by Pro. The peptidyl isomerase Pin1 specifically isomerizes the phospho-protein having Ser/Thr-Pro bond and regulates their activity. Pin1 is involved in proliferation, cell cycle, and apoptosis in cancer, by isomerizing some functional molecules such as JNK, JUN, cyclin D, BAX, etc. However, it is controversial whether direct interaction of Pin1 with eNOS and how eNOS activity is altered by Pin1, especially in PH.

Purpose

We aimed to clarify whether Pin1 contributes to the PH development using Pin1 knockout mice and Pin1 affects the expression of phosphorylated eNOS (p-eNOS) molecule and pulmonary arterial endothelial cell (PAEC) apoptosis.

Methods and results

Wild (WT) and Pin1-deficient mice (KO) were exposed to hypoxia (10% O2) or normoxia for 3 weeks to generate hypoxia-induced PH. Hypoxia-inducible factor (HIF1α) expression in lungs was significantly enhanced in WT-hypoxia (WH, n=6) and KO-hypoxia (KH, n=6), suggesting that hypoxic response was certainly occurred in these mice. Pulmonary arterial pressure did not elevate in KH compared with KO-normoxia (KN, n=6) and WT-normoxia (WN, n=6), it was significantly increased only in WH (P&lt;0.01), indicating that KO did not develop PH by hypoxia. The gain of RV weight was parallel to the increase of pulmonary arterial pressure. Western blot showed that p-eNOS expression in lungs was significantly decreased in WH compared to WN, however, the expression was not different between KH and KN. It suggests that Pin1 plays a regulatory role in p-eNOS expression in hypoxic response. In cultured PAECs, the expression of p-eNOS and eNOS was markedly increased by siRNA-mediated Pin1 knockdown. Immunoprecipitation study showed the possibility of Pin1 binding to p-eNOS molecule. Apoptosis evaluated by caspase-3/7 activity by fluorescent assay and cleaved caspase-3 expression by Western blot was significantly increased by Pin1 overexpression in PAECs; however, it was significantly decreased by Pin1 knockdown. Moreover, the exaggeration of apoptosis induced by doxorubicin was markedly increased by Pin1 overexpression compared with control in PAECs; however, it was clearly suppressed by Pin1 knockdown.

Conclusion

This study suggests that endogenous Pin1 contributes to the development of PH partly via the dysfunction of PAECs, that is, by the interference with p-eNOS expression and by the increase of apoptosis inducibility to external stimuli.

Funding Acknowledgement

Type of funding source: Public grant(s) – National budget only. Main funding source(s): JSPS KAKENHI

Strongyloides stercoralis colitis in a patient positive for human T-cell leukaemia virus with rheumatoid arthritis during an anti-rheumatic therapy: a case report

An elderly woman with rheumatoid arthritis (RA) presented with a chief complaint of abdominal pain and diarrhoea while undergoing treatment with low-dose corticosteroids and abatacept. Endoscopic and histopathological findings revealed manifestations of ulcerative colitis (UC). An intermediate dose of corticosteroids and 5-aminosalicylic acid were administered. Abatacept was discontinued; the anti-TNF biologic, golimumab, was administered for treatment of both RA and UC. However, colitis worsened in response to this therapeutic regimen. Colonoscopy revealed severe mucosal lesions; larvae were detected in samples taken from multiple shallow mucosal ulcers. The patient was diagnosed with Strongyloides stercoralis colitis based on the results of an anti-parasite antibody test and examination of the larval DNA. Furthermore, serology revealed a positive test for antibodies against human T-cell leukaemia virus type 1 (HTLV-1). Immunosuppressive treatment was terminated; ivermectin was administered, which resulted in improvements in colitis symptoms within a few weeks. There are several published reports describing S. stercoralis colitis as a lethal mimic of UC. Corticosteroid and anti-TNF therapies have been reported as among the major risk factors associated with strongyloidiasis in patients with HTLV-1 infection. Therefore, HTLV-1 and Strongyloides infections may be considered in cases of new-onset gastrointestinal symptoms during immunosuppressive therapy, particularly in HTLV-1-endemic regions.

Phylogenetic relationships of Strongyloides species in carnivore hosts

Strongyloides stercoralis is a parasitic nematode and a major pathogen responsible for human strongyloidiasis. The presence of this species in the dog population has led to an interest in studying the phylogenetic relationships among Strongyloides spp. in carnivore hosts. In the present study, Strongyloides spp. from various carnivore hosts (raccoon, Japanese badger, Siberian weasel, raccoon dog, masked palm civet, and domestic cat) were sought. Except for civets, Strongyloides spp. were identified in all host species. Based on 18S rDNA sequences, nine OTUs (operational taxonomy units) were identified. Molecular phylogenetic analyses using 18S28S rDNA and mitochondrial cox1 (cytochrome c oxidase subunit 1) sequences clustered them into two groups. The first group (named the stercoralis/procyonis group) was comprised of six OTUs and occurred in cats, raccoon dogs, raccoons (S. procyonis), Siberian weasels, and Japanese badgers and included S. stercoralis from humans and dogs. The second group (named the planiceps group) was made up of Strongyloides spp. from raccoon dogs (two OTUs) and one OTU from Siberian weasels. Subsequent analysis using almost the full-length nucleotide sequences of protein-coding genes in their mitochondrial genomes placed Strongyloides spp. of cats in a sister taxon position to S. stercoralis, whereas S. procyonis from raccoons was more distantly related to them. The presence of Strongyloides spp. from various carnivore hosts, which are close relatives of S. stercoralis, suggests this group of Strongyloides (the stercoralis/procyonis group) essentially evolved as parasites of carnivores, although more data on Strongyloides spp. from primate hosts are needed.

Serum immunoglobulin G antibody titer to Fusobacterium nucleatum is associated with unfavorable outcome after stroke

Stroke can be a cause of death, while in non-fatal cases it is a common cause of various disabilities resulting from associated brain damage. However, whether a specific periodontal pathogen is associated with increased risk of unfavorable outcome after stroke remains unknown. We examined risk factors for unfavorable outcome following stroke occurrence, including serum antibody titers to periodontal pathogens. The enrolled cohort included 534 patients who had experienced an acute stroke, who were divided into favorable (n = 337) and unfavorable (n = 197) outcome groups according to modified ranking scale (mRS) score determined at 3 months after onset (favorable = score 0 or 1; unfavorable = score 2-6). The associations of risk factors with unfavorable outcome, including serum titers of IgG antibodies to 16 periodontal pathogens, were examined. Logistic regression analysis showed that the initial National Institutes of Health stroke scale score [odds ratio (OR) = 1·24, 95% confidence interval (CI) = 1·18-1·31, P < 0·001] and C-reactive protein (OR = 1·29, 95% CI = 1·10-1·51, P = 0·002) were independently associated with unfavorable outcome after stroke. Following adjustment with those, detection of the antibody for Fusobacterium nucleatum ATCC 10953 in serum remained an independent predictor of unfavorable outcome (OR = 3·12, 95% CI = 1·55-6·29, P = 0·002). Determination of the antibody titer to F. nucleatum ATCC 10953 in serum may be useful as a predictor of unfavorable outcome after stroke.

Establishment of a serodiagnosis system for the detection of Toxocara spp. and Ascaris suum infection in chickens

Chickens are considered to act as paratenic hosts for agents, Toxocara canis, T. cati and Ascaris suum; which cause ascarid larva migrans syndrome (ascarid LMS) in humans. In addition, they are the definitive host for Ascaridia galli, considered not to be infective for humans. All ascarid parasites can have a high homology of antigenicity, leading to cross-reactivity in serodiagnostic assays. This study was conducted to establish a procedure for the serological detection of those roundworm infections in chickens. Twenty-five male Julia chickens were divided into five groups (n = 5); T. canis-, T. cati-, Ascaris suum- and Ascaridia galli-infected, and an uninfected control group. In Ascaris suum-soluble worm antigen preparation (As-SWAP) ELISA, all infected groups showed an elevation of anti-ascarid antibodies, indicating the usefulness of As-SWAP as a screening antigen for the detection of ascarid infections. For infecting species identification, T. canis-excretory/secretory (Tc-ES) and Ascaris suum-ES (As-ES) antigen ELISA were conducted by serial dilution sera. Toxocara spp.-infected sera showed stronger binding to Tc-ES than As-ES, while Ascaris suum and Ascaridia galli-infected sera bound to As-ES more strongly than Tc-ES. To discriminate between Ascaris suum and Ascaridia galli infection, sera were pre-incubated with Ascaridia galli-SWAP antigen and applied to Tc-ES and As-ES ELISAs. In this pre-adsorbed ES antigen ELISAs, only the Ascaris suum infected group showed positive binding to As-ES, resulting from the adsorption of cross-reactive antibodies in Ascaridia galli-infected sera. Finally, anti-Toxocara specific antibodies were confirmed by Tc-ES western blot (WB). Toxocara spp.-infected sera showed toxocariasis-specific band pattern in Tc-ES WB, while no specific band appeared on any strip incubated with Ascaris suum, Ascaridia galli-infected and uninfected sera. In conclusion, the serodiagnostic assays evaluated in this study are useful for the detection of ascarid infections in chickens.

Paragonimus and paragonimiasis in Asia: An update

Paragonimiasis, or lung fluke disease, is a typical food-borne parasitic zoonosis caused by infection with trematodes belonging to the genus Paragonimus. More than 50 species of Paragonimus have been reported throughout the world, of which seven valid species infect humans, an estimated one million people annually worldwide. Among the seven species, P. westermani, P. heterotremus, and P. skrjabini/P. s. miyazakii, distributed in Asia, are the most important species as the cause of paragonimiasis. Humans acquire infection through the ingestion of raw, pickled or undercooked freshwater crustaceans, 2nd intermediate hosts, or consuming raw meat of wild boar or deer, paratenic hosts. Infections often occur clustered in foci where dietary habits allow transmission of the parasites. Paragonimiasis typically causes a subacute to chronic inflammatory disease of the lungs. The symptoms, including chronic cough, chest pain, dyspnea and hemoptysis, mimic those of tuberculosis and lung cancer. Serologic tests are commonly used for the diagnosis of paragonimiasis, and Praziquantel is the treatment of choice. In this review, the current status of Paragonimus and paragonimiasis in Asia is outlined based on the latest information and findings. We also summarize current trends of paragonimiasis in Japan, which is one of the most endemic area of paragonimiasis in the world, for the better understanding and control of paragonimiasis.

P6012Active selexipag metabolite MRE-269 increases endothelin receptors in pulmonary artery smooth muscle cells

Background

The pathology of pulmonary arterial hypertension (PAH) indicates the abnormal outgrowth of pulmonary artery smooth muscle cells (PASMCs) of the media. Abundant expression of endothelin 1 (ET-1) is observed in vessels of PAH, and has been considered to play a pathogenic role. There are several endothelin receptors including ETA, ETB. Compared to ETA, ETB mRNA is less expressed in PASMCs from control individuals, and is reported to be increased in those from PAH patients. However, how ETB is involved in PAH remains unclear. Selexipag, a non-prostanoid IP receptor agonist, was recently authorized for treating PAH. Compared to selexipag, the active metabolite MRE-269 has a higher affinity for the IP receptor. Initial combination therapy come to be accepted as a standard strategy for this disease, although the interaction of each drug has not been discussed enough.

Purpose

To assess the effect of selexipag on ET-1 receptors in PASMCs.

Methods

We stimulated purchased human PASMCs and endothelial cells by MRE-269 (300 nM), ET-1 (100 nM) or combination of them in vitro. Quantitative PCR was performed to quantify mRNA expressions. Cell proliferation was assessed by CCK8 cell proliferation assay kit. BQ123, A192621, bosentan was used as blocker against ETA, ETB, or both, respectively.

Results

In PASMCs, MRE-269 increased ETA and ETB expressions 2- and 7-fold, respectively. On the other hand, it increased ETB 1.2-fold in pulmonary artery endothelial cells; ETA was not detected in those cells. After pretreatment by MRE-269, ET-1 accelerated the proliferation of PASMCs. A192621 and bosentan abrogated this proliferation. In contrast, BQ123 did not abrogate it.

Conclusions

In PASMCs, active selexipag metabolite MRE-269 increases ETB more strongly than ETA, resulting in accelerated cell proliferation by ET-1 predominantly via ETB. These data call for further study focused on the choice of ET-1 receptor antagonists in the case of combination therapy with selexipag.

Characterization of the RAGE-binding protein, Strongyloides venestatin, produced by the silkworm-baculovirus expression system

The receptor for advanced glycation end products (RAGE) recognizes Ca⁺⁺-binding proteins, such as members of the S100 protein family released by dead or devitalized tissues, and plays an important role in inflammatory responses. We recently identified the Ca⁺⁺-binding protein, venestatin, secreted from the rodent parasitic nematode, Strongyloides venezuelensis. We herein characterized recombinant venestatin, which is abundantly produced by the silkworm-baculovirus expression system (silkworm-BES), particularly in its interaction with RAGE. Venestatin from silkworm-BES possessed a binding capacity with Ca⁺⁺ ions and vaccine immunogenicity against S. venezuelensis larvae in mice, which is similar to venestatin produced by the E. coli expression system (EES). Venestatin from silkworm-BES had a higher affinity for human recombinant RAGE than that from EES, and their affinities were Ca⁺⁺-dependent. RAGE in the mouse lung co-immunoprecipitated with venestatin from silkworm-BES administered intranasally, indicating that it bound endogenous mouse RAGE. The present results suggest that venestatin from silkworm-BES affects RAGE-mediated pathological processes.

Two cases of cutaneous gnathostomiasis after eating raw Salangichthys microdon (icefish, shirauo)

Cutaneous gnathostomiasis (CG) is a disease caused by ingestion of third-stage Gnathostoma larva in raw snakes, freshwater fish or frogs. The common causative organisms of CG in Japan include G. nipponicum, G. spinigerum, G. doloresi, G. binucleatum and G. hispidum. We report two cases of CG after eating many raw Japanese icefishes (Salangichthys microdon). In both cases, linear itchy eruptions on the trunk developed after eating many S. microdon. We performed genetic analysis in the first case, which revealed G. nipponicum. Of note, this is the first case of CG diagnosed based on genetic analysis in Japan. In Japan, eating whole small raw freshwater fish is common. The most popular types of raw small freshwater fish consumed in Japan are S. microdon (shirauo in Japanese) and Leucopsarion petersii (shirouo in Japanese). Usually, S. microdon are born in rivers, but live in both the sea and rivers. They feed on small fish and freshwater water fleas and spawn in rivers in the spring. On the other hand, L. petersii are born in rivers, but move to the sea soon after hatching. They feed on plankton such as copepod in the sea. They do not feed on anything when they return to rivers to spawn in the spring. Therefore, we hypothesize that S. microdon are more easily parasitized by G. nipponicum.

Sequential Changes in the Host Gut Microbiota During Infection With the Intestinal Parasitic Nematode Strongyloides venezuelensis

Soil-transmitted helminths (STHs) are medically important parasites that infect 1. 5 billion humans globally, causing a substantial disease burden. These parasites infect the gastrointestinal tract (GIT) of their host where they co-exist and interact with the host gut bacterial flora, leading to the coevolution of the parasites, microbiota, and host organisms. However, little is known about how these interactions change through time with the progression of infection. Strongyloidiasis is a human parasitic disease caused by the nematode Strongyloides stercoralis infecting 30-100 million people. In this study, we used a closely related rodent parasite Strongyloides venezuelensis and mice as a model of gastrointestinal parasite infection. We conducted a time-course experiment to examine changes in the fecal microbiota from the start of infection to parasite clearance. We found that bacterial taxa in the host intestinal microbiota changed significantly as the infection progressed, with an increase in the genera Bacteroides and Candidatus Arthromitus, and a decrease in Prevotella and Rikenellaceae. However, the microbiota recovered to the pre-infective state after parasite clearance from the host, suggesting that these perturbations are reversible. Microarray analysis revealed that this microbiota transition is likely to correspond with the host immune response. These findings give us an insight into the dynamics of parasite-microbiota interactions in the host gut during parasite infection.

Factor XII deficiency is common in domestic cats and associated with two high frequency F12 mutations

Factor XII (FXII) is a coagulation protein that initiates surface-activation of the coagulation cascade in vitro. The protein's in vivo role, however, remains poorly defined. Factor XII deficiency, or Hageman trait, is a rare hereditary disorder that is not associated with bleeding, and wide variations in FXII activity (FXII:C) exist among healthy people. While FXII-deficient knockout mice appear to be resistant to arterial thrombosis, human F12 polymorphisms that influence FXII:C have not been associated with thrombotic risk in population surveys. Factor XII deficiency is a naturally occurring hereditary trait in domestic cats. We undertook phenotypic and genotypic analyses of FXII-deficient cats for comparative studies with the human disease counterpart. A retrospective review of feline submissions to our laboratory revealed that FXII deficiency is common in domestic cats, and also present in many different breeds. The trait has a geographic bias toward the Midwestern United States. Clinical history, coagulation assays, and samples for F12 sequencing were obtained from 26 FXII deficient cats. None of the cats had experienced abnormal bleeding and their residual FXII:C was related to F12 mutation number and mutation-type. We found 2 high frequency F12 mutations: an exon 13 missense mutation (c.1631G > C) and an exon 11 deletion mutation (c.1321delC), and additional sequence variants throughout the gene. Factor XII deficiency in pet cat populations provides an animal model system to help clarify the biologic actions and clinical relevance of FXII protein.

Secretome analysis of Strongyloides venezuelensis parasitic stages reveals that soluble and insoluble proteins are involved in its parasitism

Background

Parasites excrete and secrete a wide range of molecules that act as the primary interface with their hosts and play critical roles in establishing parasitism during different stages of infection. Strongyloides venezuelensis is a gastrointestinal parasite of rats that is widely used as a laboratory model and is known to produce both soluble and insoluble (adhesive) secretions during its parasitic stages. However, little is known about the constituents of these secretions.

Results

Using mass spectrometry, we identified 436 proteins from the infective third-stage larvae (iL3s) and 196 proteins from the parasitic females of S. venezuelensis. The proteins that were secreted by the iL3s were enriched with peptidase activity, embryo development and the oxidation-reduction process, while those of the parasitic females were associated with glycolysis, DNA binding (histones) and other unknown functions. Trypsin inhibitor-like domain-containing proteins were identified as the main component of the adhesive secretion from parasitic females. An absence of secretion signals in many of the proteins indicated that they are secreted via non-classical secretion pathways.

Conclusions

We found that S. venezuelensis secretes a wide range of proteins to establish parasitism. This includes proteins that have previously been identified as being involved in parasitism in other helminths as well as proteins that are unique to this species. These findings provide insights into the molecular mechanisms underlying Strongyloides parasitism.

Electronic supplementary material

The online version of this article (10.1186/s13071-018-3266-x) contains supplementary material, which is available to authorized users.

Prevalence and associated risk factors of Strongyloides stercoralis infection in Lower Myanmar

Background

Strongyloidiasis is prevalent in Southeast Asian regions along with other soil-transmitted helminthiases, but only limited present-day data was available for Myanmar.

Methods

A prevalence survey for Strongyloides stercoralis infection was conducted among villagers in rural areas of three townships located in the Lower Myanmar during 2014–2016 by agar plate culture method in combination with specific identification by molecular assays. Risk factors associated with S. stercoralis infection were assessed by analyzing questionnaires obtained from study participants.

Results

Strongyloides stercoralis was identified in 40 out of 703 participants (5.7% overall prevalence). The highest prevalence (14.4%) was observed in Htantabin, while other two communities (Thabaung and Thanlyin) had much lower prevalence (2.2 and 2.5%, respectively). Infection was relatively rare (1.2%) in younger generations under 20 years compared to older generations (9.5%). Even in Htantabin, none of the female residents under age 40 (n = 33) had infection. In adult Htantabin residents, those who answered that they do not wear shoes regularly had an elevated risk of infection (odds ratio = 2.50, 95% confidence interval = 1.03–6.08).

Conclusions

This study showed that there is still an on-going transmission of strongyloidiasis in Lower Myanmar. It is highly desirable that the soil should be free of fecal contamination by improving the management of fecal waste. Meanwhile, health education to promote shoe-wearing would be beneficial to reduce the risk of transmission, especially for those who have frequent and intense contact with soil.

Takotsubo cardiomyopathy associated with Paragonimiasis westermani

An 11-year-old boy collapsed during morning assembly at his junior high school. The automated external defibrillator detected ventricular fibrillation and provided shock delivery. He was successfully resuscitated and reverted to sinus rhythm. Electrocardiography showed ST-T elevation in the precordial leads. Echocardiography and angiography demonstrated akinesia of the apex and mid-wall of the left ventricle with preserved contraction of the basal segments, which suggested Takotsubo cardiomyopathy. The patient and his family had often eaten uncooked crab, and his father had a past history of infection with Paragonimiasis westermani. The patient had had a persistent cough and chest pain for several weeks. Chest radiograph showed cystic cavities in the left upper lung. Microbiological examination of the sputum demonstrated an egg of P. westermani and immunological assay showed a raised antibody titre to P. westermani. On the12th day of admission, he developed seizures, and magnetic resonance imaging demonstrated cerebral involvement. After the administration of praziquantel for 3 days, the clinical manifestations improved immediately, and echocardiography normalised within 3 weeks. The patient was discharged on the 32nd day + and follow-up was normal. Takotsubo cardiomyopathy following a potentially fatal arrhythmia is a rare cardiac complication associated with pulmonary and central nervous system infection by P. westermani.

Evaluation of LIPS (luciferase immunoprecipitation system) for serodiagnosis of Toxoplasmosis

Development of reliable, quantitative technologies for serodiagnosis of Toxoplasma gondii infection remains desirable. The luciferase immunoprecipitation system (LIPS) is a relatively simple, highly sensitive, and rapid quantitative immunoassay. The major advantages of this assay over ELISA are a wider dynamic range, shorter overall assay time, and less sample volume. In this study, we aimed to use this method for the serodiagnosis of toxoplasmosis. Recombinant Toxoplasma antigens (dense granule antigens GRA6, GRA7, and GRA8 and bradyzoite antigen BAG1) fused with nanoluciferase (Nluc, a small luciferase enzyme) were expressed in Escherichia coli, purified, and tested in LIPS assays with sera from experimental mice infected with T. gondii and a WHO standard anti-Toxoplasma human immunoglobulin (TOXM). In the experimentally infected mice, LIPS assays detected antibodies against Nluc-GRA6, Nluc-GRA7, and Nluc-GRA8 as early as day 14, whereas antibodies against Nluc-BAG1 remained undetected until day 21 and then showed significant elevation on day 60. In TOXM sera, LIPS assays with each Nluc recombinant protein produced reliable standard curves with a coefficient of determination (R²) of 0.980-0.989 for GRA6, 0.986-0.990 for GRA7, 0.998-0.999 for GRA8, and 0.942-0.987 for BAG1. The detection limits were estimated to be 3.9, 2, 1, and 1 IU/ml for rGRA6, rGRA7, rGRA8, and rBAG1, respectively. The LIPS assay for toxoplasmosis could detect antibodies against T. gondii in the mouse and human sera with a reasonably high sensitivity. We consider the LIPS assay to be a promising alternative tool for screening, diagnosing, and monitoring toxoplasmosis. In particular, detection of antibodies against BAG1 may be useful for a longitudinal seroprevalence study in suspected high-risk areas on the basis of its elevated serum concentration in the chronic phase.

Cerebral Paragonimiasis With Hemorrhagic Stroke in a Developed Country

Paragonimiasis is a food-borne parasitic disease caused by Paragonimus lung flukes, which are epidemic in Asia. Cerebral paragonimiasis accounts for <1% of symptomatic paragonimiasis but is the most common extrapulmonary infection. Cerebral paragonimiasis often mimics stroke and sometimes causes severe neurological sequelae. A 61-year-old woman was admitted to the hospital for severe headache. A head computed tomography scan revealed intracerebral hemorrhage with subarachnoid hemorrhage. The patient also had lesions in the lungs. She frequently ate Japanese mitten crab. Peripheral blood examination results of increased eosinophilia and immunological testing results confirmed the diagnosis of Paragonimus westermani infection. The patient was successfully treated with praziquantel as the first-line agent. Cerebral paragonimiasis is currently rare in developed countries; however, it is an important disease to consider.

Development of nested multiplex polymerase chain reaction (PCR) assay for the detection of Toxocara canis, Toxocara cati and Ascaris suum contamination in meat and organ meats

Ascarid Larva Migrans Syndrome (ascarid LMS) is a clinical syndrome in humans, caused by the migration of animal roundworm larvae such as Toxocara canis, Toxocara cati and Ascaris suum. Humans may acquire infection by ingesting embryonated eggs, or infective larvae of these parasites in contaminated meat and organ meats. To detect these pathogenic contaminations, a novel nested multiplex PCR system was developed. Our novel nested multiplex PCR assay showed specific amplification of T. canis, T. cati and Ascaris spp. Detection limit of the nested multiplex PCR was tested with serial dilution of T. canis, T. cati or A. suum genomic DNA (gDNA) from 100 pg to 100 ag and found to be 10 fg, 1 fg and 100 fg, respectively. When larvae were spiked into chicken liver tissue, DNA of T. canis and A. suum was detected from the liver spiked with a single larva, while the assay required at least 2 larvae of T. cati. Moreover, the ascarid DNA was detected from the liver of mice infected with 100 and 300 eggs of T. canis, T. cati or A. suum. This nested multiplex PCR assay could be useful for the detection of contamination with ascarid larvae in meat and organ meats.

Retrospective observational study of the use of artemether-lumefantrine in the treatment of malaria in Japan

BACKGROUND

The Research Group on Chemotherapy of Tropical Diseases, Japan, introduced artemether-lumefantrine (AL) in late 2002, mainly for treating uncomplicated Plasmodium falciparum malaria. Because AL was on the market in Japan in March 2017, the effectiveness and safety of AL were analyzed to help medical personnel use AL optimally.

METHODS

Case report forms submitted by the attending physicians were analyzed. When necessary, direct contact with the attending physicians was made to obtain detailed information.

RESULTS

Effectiveness analysis was performed for 62 cases and safety analysis was performed for 66 cases. In P. falciparum malaria, the overall cure rate was 91.1% (51/56), of which the cure rates for Japanese and non-Japanese patients were 82.1% (23/28) and 100% (28/28), respectively. The successfully treated cases included severe P. falciparum malaria, with parasite densities exceeding 500,000/μL. Adverse events were reported in 14 patients, including delayed hemolytic anemia which occurred in the top four highest parasitemic cases.

CONCLUSIONS

AL treatment failure in P. falciparum malaria may not be rare among non-immune individuals, including Japanese. The possibility of delayed hemolytic anemia, which occurs preferentially in high parasitemic cases, should be considered following AL treatment.

Intestinal immunity suppresses carrying capacity of rats for the model tapeworm, Hymenolepis diminuta

Hymenolepis diminuta is a parasitic tapeworm of the rat small intestine and is recognized as a useful model for the analysis of cestode-host interactions. In this study, we analyzed factors affecting the biomass of the tapeworm through use of rat strains carrying genetic mutations, namely X-linked severe combined immunodeficiency (xscid; T, B and NK cells deficiency), nude (rnu; T cell deficiency), and mast cell deficient rats. The worm biomass of F344-xscid rats after infection with 5 cysticercoids was much larger than control F344 rats from 3 to 8 weeks. The biomass of F344-rnu rats was also larger than the controls, but was intermediate between F344-xscid and control rats. These observations demonstrated that host immunity can control the maximal tapeworm biomass, i.e., carrying capacity, of the rat small intestine. Both T cell and other immune cells (B and NK cells) have roles in determining the carrying capacity of tapeworms. Total worm biomass and worm numbers in mast cell deficient rats (WsRC-Ws/Ws) were not significantly different from control WsRC-+/+ rats after 3 and 6 weeks of primary infection. Mast cell deficient rats displayed reinfection resistance for worm biomass but not worm expulsion. These findings suggest that the mast cell has a role for controlling the biomass of this tapeworm in reinfection alone, but does not affect the rate of worm expulsion. Overall, our findings indicate that the mast cell is not a major effector cell for the control of the carrying capacity of tapeworms. The identity of the major effector cell remains unknown.

Severe delayed haemolytic anaemia associated with artemether-lumefantrine treatment of malaria in a Japanese traveller

Delayed haemolytic anaemia has been reported in association with intravenous artesunate treatment in patients with severe Plasmodium falciparum malaria, and furthermore, oral artemisinin-based combination therapies including artemether-lumefantrine (AL) have also been incriminated. However, definite cases of delayed haemolytic anaemia associated with AL appear to be scarce, as reported cases were often treated concomitantly with other anti-malarials. In this study, we report a severe case of delayed haemolytic anaemia following AL alone in a Japanese traveller with severe parasitaemia caused by numerous P. falciparum parasites and a few P. vivax parasites. We also stress the need by further studies to differentiate between delayed haemolytic anaemia and blackwater fever, the latter being another malaria-related haemolytic condition, more clearly than they are now.