論文 - 丸山 治彦
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Effects of toxocara canis infection on hemopoietic stem cells and hemopoietic factors in mice 査読あり
Higa A., Maruyama H., Abe T., Owhashi M., Nawa Y.
International Archives of Allergy and Immunology 91 ( 3 ) 239 - 243 1990年
記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：International Archives of Allergy and Immunology
The effects of Toxocara canis infection on hemopoietic stem cells and hemopoietic factors were examined in mice. Severe eosinophilia was observed with a peak 14 days after infection. When the numbers of hemopoietic stem cells in peripheral blood, spleen, and bone marrow were examined by spleen colony assay (CFU-S), those in peripheral blood and spleen increased in parallel with peripheral blood eosinophilia. On the other hand, CFU-S in bone marrow did not alter significantly throughout the course of infection. Interleukin (IL)-3, which is known as multi-colony-stimulating factor and is involved in the growth/differentiation of various blood cells including stem cells, was produced by spleen cells of infected mice. The time course study showed that concanavalin A stimulated IL-3 production peaked on day 7 after infection, whereas that with excretory secretory antigen peaked on day 14. Even without stimulation, spleen cells obtained on day 21 after infection produced IL-3 spontaneously. IL-5, which is known to have eosinophil differentiation factor activity, was also produced by spleen cells obtained on day 13 after infection. These results suggest that in response to increased demand for eosinophils, hemopoietic stem cells migrate into various extramedullar hemopoietic organs where they grow/differentiate into mature eosinophils, depending on the hemopoietic factors. © 1990 S. Karger AG, Basel.
DOI： 10.1159/000235123
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Satake K, Kikuchi J, Kokubo-Tanaka M, Ando T, Tanaka R, Kannae M, Hirayu N, Maruyama H, Takasu O, Morioka M
Journal of infection and chemotherapy : official journal of the Japan Society of Chemotherapy 32 ( 4 ) 102944 2026年4月
記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Journal of Infection and Chemotherapy Official Journal of the Japan Society of Chemotherapy
In recent years, the number of foreign technical intern trainees in Japan has been steadily increasing. As a result, opportunities to treat foreign patients with different cultures and customs have also increased and so has the possibility of encountering cases that have not been previously experienced. We report a case of a 25-year-old Cambodian man who is residing in Japan as a technical intern trainee. He presented with a chief complaint of headache and dizziness. After further examination, a diagnosis of intracerebral hemorrhage was made. Blood tests revealed peripheral eosinophilia, and chest computed tomography showed multiple abnormal findings, leading to the suspicion of a parasitic infection. Detailed medical history revealed a dietary history suggestive of a parasitic infection. Further, he tested positive for serum and cerebrospinal fluid antibodies against Paragonimus species and serum antibodies against liver fluke. Based on these findings, a diagnosis of a mixed infection with both parasites was made, and the intracerebral hemorrhage was determined to be due to paragonimiasis. The patient was treated with oral praziquantel, which resulted in a favorable outcome. Our experience with this case suggests that when treating foreign patients, it is essential to be mindful of their culture and customs, and that detailed questioning, including queries on lifestyle habits, can sometimes lead to an early diagnosis, making it an important step in patient care.
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Fasciolosis Reinfection in Japan.
Akiyoshi K, Kokubo-Tanaka M, Yamauchi S, Yonezu K, Abe I, Tawara K, Saito S, Kondo H, Fukuda T, Fukui A, Akioka H, Shinohara T, Teshima Y, Yufu K, Shimono N, Mizuno Y, Irie T, Yoshida A, Takahashi N, Maruyama H
Internal medicine (Tokyo, Japan) 65 ( 6 ) 921 - 925 2026年3月
記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Internal Medicine
Fasciolosis is a major cause of food-borne parasitic zoonosis. It primarily affects ruminants but also infects humans. Clinically, it is characterized by abnormal liver images with prominent eosinophilia. We herein report a 77-year-old Japanese livestock farmer, who experienced fasciolosis reinfection. Environmental investigation of his residence revealed that both intermediate host snails and sika deer, a natural final host, inhabited his house. In addition, cattle were infected with Fasciola. Based on these findings, we concluded that his work place was accidentally contaminated with Fasciola metacercariae.
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Akazawa H, Hagiya H, Fukushima S, Nakamoto K, Oguni K, Manabe Y, Kokubo-Tanaka M, Maruyama H, Otsuka F
The American journal of tropical medicine and hygiene 114 ( 3 ) 486 - 489 2026年3月
記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：American Journal of Tropical Medicine and Hygiene
Paragonimiasis is a parasitic disease caused by the genus Paragonimus, typically transmitted through the ingestion of raw or undercooked freshwater crabs. Although pulmonary involvement is typical, ectopic migration to subcutaneous or hepatic sites is rare and poses diagnostic challenges. A case of paragonimiasis in a 29-year-old Cambodian woman residing in Japan who presented with painless subcutaneous nodules on the chest and abdomen is reported in the current study. She had consumed raw crab 4 months before presentation. Laboratory findings revealed marked eosinophilia (21,000/mL) and elevated immunoglobulin E (5,049 IU/mL). Computed tomography scans revealed pleural effusion, club-shaped pulmonary consolidation, funicular hypodense lesions in the liver, and subcutaneous lesions. Stool and sputum test results were negative for parasite eggs; however, a microplate ELISA indicated a Paragonimus westermani infection. The patient responded well to 3 consecutive days of praziquantel (75 mg/kg/day) and was discharged a week later. This case highlights the importance of considering paragonimiasis in patients with unexplained subcutaneous nodules and eosinophilia, especially when supported by dietary risk factors.
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Declining Seroprevalence of Strongyloidiasis in Okinawa, Japan: A Cross-Sectional Study. 査読あり
Kosuge A, Fukuda N, Funakoshi A, Yoshida N, Nagayasu E, Miida T, Hachiman T, Maruyama H, Obara H, Mita T
The American journal of tropical medicine and hygiene 114 ( 3 ) 519 - 525 2026年3月
記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：American Journal of Tropical Medicine and Hygiene
Strongyloidiasis remains endemic in Okinawa, Japan; however, epidemiological data over the past 30 years are limited. This study aimed to assess the current seroprevalence of strongyloidiasis in Okinawa. We conducted a cross-sectional study at Okinawa Chubu Hospital in 2022. Serum samples from 1,485 participants were screened using an ELISA-based antibody test with the recombinant Strongyloides stercoralis antigen NIE. Seropositive participants underwent three stool examinations: the formalin–ether concentration method, agar plate culture, and real-time polymerase chain reaction. The crude seroprevalence was 3.2% (n 5 47/1,485, 95% CI: 2.3–4.2%), and the age-adjusted seroprevalence was 2.4% (95% CI: 1.3–4.2%). Age 80 years old or older was a significant risk factor (odds ratio: 7.84, 95% CI: 3.59–17.2; P ,0.001). This age group had 8.5% seropositivity (95% CI: 5.5–12.4%) and comprised 51.1% of all positive participants. However, five seropositive participants were ages younger than 40 years old. Of the seropositive individuals who underwent stool testing, 30.8% (n 5 8/26) had positive results, and all were 70 years old or older. Despite the absence of a strongyloidiasis control program over the past 30 years, the seroprevalence has markedly declined. The shift toward older age among seropositive participants suggests that environmental transmission is now rare in Okinawa, with most infections likely acquired decades ago. Nonetheless, the persistent high endemicity among the elderly calls for continued clinical awareness of strongyloidiasis.
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症例報告 高エコー域の不明瞭化が虫体死滅を示唆したマンソン孤虫症の1例 査読あり
四本 周, 塚田 全, 渡邉(高橋) 愛美, 小久保(田中) 美緒, 丸山 治彦
臨床皮膚科 80 ( 3 ) 225 - 229 2026年3月
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丸山 治彦, 小久保 美緒
The American journal of tropical medicine and hygiene 114 ( 3 ) 486 - 489 2025年12月
記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：American Society of Tropical Medicine and Hygiene
Paragonimiasis is a parasitic disease caused by the genus Paragonimus, typically transmitted through the ingestion of raw or undercooked freshwater crabs. Although pulmonary involvement is typical, ectopic migration to subcutaneous or hepatic sites is rare and poses diagnostic challenges. A case of paragonimiasis in a 29-year-old Cambodian woman residing in Japan who presented with painless subcutaneous nodules on the chest and abdomen is reported in the current study. She had consumed raw crab 4 months before presentation. Laboratory findings revealed marked eosinophilia (21,000/µL) and elevated immunoglobulin E (5,049 IU/mL). Computed tomography scans revealed pleural effusion, club-shaped pulmonary consolidation, funicular hypodense lesions in the liver, and subcutaneous lesions. Stool and sputum test results were negative for parasite eggs; however, a microplate ELISA indicated a Paragonimus westermani infection. The patient responded well to 3 consecutive days of praziquantel (75 mg/kg/day) and was discharged a week later. This case highlights the importance of considering paragonimiasis in patients with unexplained subcutaneous nodules and eosinophilia, especially when supported by dietary risk factors.
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Eguchi Mako, Masumoto Keisuke, Maruyama Haruhiko, Kokubo-Tanaka Mio, Morimoto Satoru, Mizuta Yuichi
Cureus 17 ( 8 ) e90032 2025年8月
記述言語：英語 掲載種別：症例報告 出版者・発行元：Springer Science and Business Media LLC
Paragonimiasis is a foodborne parasitic infection caused by trematodes of the genus Paragonimus, primarily P. westermani and P. miyazakii in Japan. Though once endemic, its incidence has declined significantly in recent decades. However, globalization, changes in dietary customs, and an increase in foreign-born residents have contributed to the emergence of new cases, particularly in urban settings.
We present a case of a 25-year-old man from Cambodia, living in Japan for two years as a technical intern trainee, who developed a productive cough and pleuritic chest pain. He reported consuming raw Japanese mitten crabs seven months earlier. Initially misdiagnosed with pneumonia, his symptoms persisted despite antibiotic therapy. CT imaging revealed pleural effusion, a cavitary lesion, and a linear tract consistent with worm migration. A subcutaneous abdominal mass was noted and surgically removed. Histopathological examination revealed eosinophilic infiltration and serpiginous necrosis, suggesting larval migration. Laboratory tests showed marked eosinophilia (11,011/μL), and pleural fluid analysis indicated pseudochylothorax. ELISA confirmed antibodies against P. westermani and P. miyazakii. The patient was treated with praziquantel, leading to complete clinical and radiological resolution.
This case highlights the diagnostic challenges of paragonimiasis, especially with atypical presentations. Subcutaneous lesions are rare and often mimic benign tumors or other parasitic diseases, such as sparganosis or cysticercosis. The pulmonary findings may be confused with tuberculosis or eosinophilic pneumonia. Thus, thorough dietary and travel history-taking, cultural awareness, and a multidisciplinary diagnostic approach, including imaging, histology, and serology, are essential. Diagnosis of paragonimiasis should rely on a combination of clinical presentation, radiological findings, and serological testing, as ectopic manifestations are uncommon and may not be promptly recognized. This case underscores the need for heightened clinical awareness of re-emerging parasitic diseases in increasingly multicultural societies. -
Subcutaneous Migration in Paragonimiasis as a Diagnostic Clue in an Unusual Presentation: A Case Report. 査読あり
Eguchi M, Masumoto K, Kokubo-Tanaka M, Maruyama H, Morimoto S, Mizuta Y
Cureus 17 ( 8 ) e90032 2025年8月
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症例報告 Creeping diseaseの3例 査読あり
太田 志野, 和田 麻依, 松井 はるか, 田中 美緒, 丸山 治彦, 長谷川 英男, 河原 由恵
臨床皮膚科 79 ( 2 ) 159 - 164 2025年2月
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Down-regulation of colon mucin production induced by Eimeria pragensis infection in mice. 査読あり
Setia YD, Kokubo-Tanaka M, Tanaka R, Yoshida A, Nagayasu E, Ahmadi P, Yoshida A, Maruyama H
Frontiers in parasitology 4 1621486 2025年
記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Frontiers in Parasitology
Introduction: Eimeria pragensis, an intestinal protozoa infecting mice, induces colitis and reduces goblet cell numbers in the large intestine. In the present study, we investigated the pathogenesis and the mechanisms underlying goblet cell down-regulation in the early phase of infection. Methods: Male C57BL/6 mice were orally infected with 300 oocysts. Fecal oocyst shedding and body weight were monitored daily. Colon tissues were collected at 3, 8, and 13 days post-infection (dpi) to assess pathological changes. Parasite burden was assessed by histological analysis (H&E staining) and qPCR targeting 5S rRNA. Goblet cells were visualized using PAS-Alcian Blue staining and Muc2 immunohistochemistry. To elucidate mechanisms of goblet cell dysfunction, we performed RNA sequencing of large intestine tissue to examine host as well as parasite transcriptomes. Results: Fecal oocyst excretion peaked at 8–9 dpi. Body weight decreased from 6 to 11 dpi, with recovery after 12 dpi. Maximal parasite accumulation in the proximal colon was observed at 8 dpi in histological examination as well as qPCR. Colon length was significantly shortened at 3 dpi. Goblet cell area significantly reduced at 8 dpi (p < 0.05). RNA sequencing of infected large intestines revealed that E. pragensis produced enzymes that were known to degrade mucin and tight junctions, and proteins that could activate the Notch–Hes1 signaling pathway. As for host responses, genes associated with Th1-type inflammation, epithelial barrier disruption, and immune regulation were up-regulated as early as 3 dpi. Discussion: Our findings suggested that E. pragensis infection induces a mucosal barrier dysfunction in the early phase of the infection, which possibly causes the tissue invasion of bacteria in the large intestine. Th1-type inflammatory response, thus induced, reduces goblet cell numbers and mucin production. This model provides valuable insight into the mechanisms of mucosal barrier disruption during protozoan infection.
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Serial changes in B-cell subsets and immunoglobulin G4 levels in paragonimiasis. 査読あり
Taku K, Ogata M, Hoshina T, Maruyama H, Yoshida A, Kusuhara K
Pediatrics international : official journal of the Japan Pediatric Society 66 ( 1 ) e15727 2024年1月
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A delayed diagnosis of fascioliasis: The importance of appropriate fecal diagnostic method. 査読あり
Kosaka S, Shimizu S, Nakayamada S, Nawata A, Shimono N, Tanaka M, Maruyama H, Osada Y, Tanaka Y
Journal of infection and chemotherapy : official journal of the Japan Society of Chemotherapy 30 ( 5 ) 454 - 458 2023年11月
記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Journal of Infection and Chemotherapy
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.
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Four cases of gnathostomiasis due to the ingestion of raw Salangichthys microdon. 査読あり
Abe T, Hida T, Kamiya T, Ebata K, Sugita S, Kaneko R, Tanaka M, Maruyama H, Suzuki A, Uhara H
The Journal of dermatology 51 ( 2 ) e59 - e60 2023年10月
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Maekawa K, Nagayasu E, Hata Y, Hanamure F, Maruyama H, Yamashita A
Pathology international 73 ( 8 ) 373 - 376 2023年8月
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Ko PP, Haraguchi M, Hara T, Hieu DD, Ito A, Tanaka R, Tanaka M, Suzumura T, Ueda M, Yoshida A, Maruyama H, Nagayasu E
Parasitology international 92 102663 2023年2月
記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Parasitology International
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.
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臨床的に肝蛭症と診断し，トリクラベンダゾール内服後に抗体が陽転した1例 査読あり
谷口 昌史, 阪上 順一, 原 祐, 服部 知恵, 住吉 翔元, 酒井 浩明, 岡 浩平, 岩井 直人, 辻 俊史, 奥田 隆史, 小牧 稔之, 香川 惠造, 丸山 治彦
感染症学雑誌 97 ( 1 ) 32 - 37 2023年1月
担当区分：最終著者 記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：一般社団法人 日本感染症学会
We report the case of a Vietnamese man in his twenties who presented with a few days' history mild fever and severe pain in the right hypochondrium. Laboratory findings showed elevated levels of the hepatobiliary enzymes and marked peripheral blood eosinophilia. Abdominal computed tomography (CT) showed map-like low density areas with unclear boundaries under the liver capsule. Suspecting a parasitic infection, we conducted enzyme linked immunosorbent assay (ELISA) for a panel of parasite antigens, including <i>Fasciola</i> antigen. However, no positive results for any parasites were obtained. Re-examination by contrast-enhanced CT revealed that the hepatic mass had moved and findings suggestive of perihepatic inflammation. Fascioliasis was suspected, and the ELISA for <i>Fasciola</i> antigen was repeated again after a period of time, but the result was again negative. Despite the negative test result, the patient was diagnosed as having fascioliasis, based on the severe pain in the right abdomen, persistent eosinophilia, and mobile liver mass, all of which are characteristic symptoms of fascioliasis. For the treatment with triclabendazole (TCB), he was referred to a hospital in the Research Group on Chemotherapy of Tropical Diseases, Japan, which imports nationally unlicensed medicines, including TCB. After the patient received treatment with TCB (10mg/kg), the symptoms disappeared, and the eosinophil counts decreased. Serological testing at 4 weeks after the TCB administration revealed positive antibody results for crude as well as recombinant <i>Fasciola</i> antigen. Fascioliasis is a relatively rare disease, with only few cases per year reported in Japan. There are no worm eggs in the feces in the acute phase, and serological analysis (such as antibody testing) is the basis for the diagnosis. However, in this case, tests for the <i>fasciola</i> antibody initially remained negative. It should be noted that serological analysis can be negative in the early stage of the disease.
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Sasaki J, Matsuoka M, Kinoshita T, Horii T, Tsuneyoshi S, Murata D, Takaki R, Tominaga M, Tanaka M, Maruyama H, Kawayama T, Hoshino T
Medicina (Kaunas, Lithuania) 59 ( 1 ) 2023年1月
記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Medicina (Lithuania)
Paragonimiasis caused by trematodes belonging to the genus Paragonimus is often accompanied by chronic respiratory symptoms such as cough, the accumulation of sputum, hemoptysis, and chest pain. Prolonged symptoms, including respiratory symptoms, after coronavirus disease 2019 infection (COVID-19) are collectively called post-COVID-19 conditions. Paragonimiasis and COVID-19 may cause similar respiratory symptoms. We encountered five cases of paragonimiasis in patients in Japan for whom diagnoses were delayed due to the initial characterization of the respiratory symptoms as a post-COVID-19 condition. The patients had consumed homemade drunken freshwater crabs together. One to three weeks after consuming the crabs, four of the five patients were diagnosed with probable COVID-19. The major symptoms reported included cough, dyspnea, and chest pain. The major imaging findings were pleural effusion, pneumothorax, and nodular lesions of the lung. All the patients were diagnosed with paragonimiasis based on a serum antibody test and peripheral blood eosinophilia (560–15,610 cells/μL) and were treated successfully with 75 mg/kg/day praziquantel for 3 days. Before diagnosing a post-COVID-19 condition, it is necessary to consider whether other diseases, including paragonimiasis, may explain the symptoms. Further, chest radiographic or blood tests should be performed in patients with persistent respiratory symptoms after being infected with COVID-19 to avoid overlooking the possibility of infection.
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Sakakura S, Yamaguchi F, Abe T, Cho H, Shimizu S, Mase A, Shikama Y, Maruyama H
Infection and drug resistance 16 2429 - 2432 2023年
担当区分：最終著者 記述言語：英語 掲載種別：症例報告 出版者・発行元：Infection and Drug Resistance
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.
DOI： 10.2147/IDR.S402392
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症例 感染源が不明であったドロレス顎口虫による皮膚爬行症の1例 査読あり
熊田 大樹, 猪爪 隆史, 栗田 遼二, 野呂瀬 一美, 彦坂 健児, 丸山 治彦, 松江 弘之
皮膚科の臨床 64 ( 10 ) 1727 - 1730 2022年9月