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Reports of non-HIV PJP associated with novel immunomodulatory agents, particularly Janus kinase (JAK) inhibitors, have increased. This case describes a 53-year-old HIV-negative Japanese veterinarian using oclacitinib (a veterinary JAK1 inhibitor for canine atopic dermatitis) daily for about 2 years.",{"@graph":69,"@context":122},[70,84,105],{"@type":71,"itemListElement":72},"BreadcrumbList",[73,77,79,82],{"item":74,"name":75,"@type":76,"position":8},"https://docshare.wps.com","Home","ListItem",{"item":78,"name":9,"@type":76,"position":14},"https://docshare.wps.com/document/",{"item":80,"name":35,"@type":76,"position":81},"https://docshare.wps.com/document/healthcare/",3,{"item":83,"name":65,"@type":76,"position":19},"https://docshare.wps.com/document/pneumocystis-jirovecii-pneumonia-in-a-human-caused-by-long-term-use-of-veterinary-drug-oclacitinib-a-case-report/443215/",{"url":83,"name":65,"@type":85,"image":86,"author":91,"headline":65,"publisher":94,"fileFormat":97,"inLanguage":63,"description":67,"dateModified":98,"datePublished":99,"encodingFormat":97,"isAccessibleForFree":100,"interactionStatistic":101},"DigitalDocument",{"url":87,"@type":88,"width":89,"height":90},"https://docshare.wps.com/thumbnails/pneumocystis-jirovecii-pneumonia-in-a-human-caused-by-long-term-use-of-veterinary-drug-oclacitinib-a-case-report/443215.png","ImageObject",300,407,{"name":92,"@type":93},"Eliana","Person",{"url":74,"name":95,"@type":96},"DocShare","Organization","application/pdf","2026-10-30","2026-09-29",true,{"@type":102,"interactionType":103,"userInteractionCount":52},"InteractionCounter",{"@type":104},"ViewAction",{"@type":106,"mainEntity":107},"FAQPage",[108,114,118],{"name":109,"@type":110,"acceptedAnswer":111},"Who developed the PJP described in the case report?","Question",{"text":112,"@type":113},"A 53-year-old HIV-negative Japanese man, working as a veterinarian, presented with progressive exertional dyspnea and fever after a long period of oclacitinib self-administration.","Answer",{"name":115,"@type":110,"acceptedAnswer":116},"How was PJP diagnosed in this patient?",{"text":117,"@type":113},"Diagnosis was confirmed using polymerase chain reaction of bronchoalveolar lavage fluid and Grocott’s methenamine silver staining of transbronchial lung biopsy specimens.",{"name":119,"@type":110,"acceptedAnswer":120},"What treatment led to recovery, and did the patient have recurrence?",{"text":121,"@type":113},"He was initially treated with trimethoprim-sulfamethoxazole and corticosteroids, then switched to atovaquone due to hepatotoxicity. The patient fully recovered and remained recurrence-free at 1-year follow-up.","https://schema.org",{"og:url":83,"og:type":124,"og:title":65,"og:site_name":95,"og:description":67},"article",{"robots":126,"canonical":83},"index,follow",{"doc_id":128,"site_id":62},443215,1791241232,{"code":4,"msg":5,"data":131},{"doc_id":128,"user_id":132,"nickname":92,"user_avatar":133,"doc_module":4,"category_id":34,"category_name":35,"doc_title":65,"doc_description":67,"doc_content":134,"file_id":135,"file_url":136,"file_type":137,"file_size":138,"view_count":52,"is_deleted":4,"is_public":8,"is_downloadable":8,"audit_status":8,"page_count":24,"language":139,"language_code":63,"site_id":62,"html_lang":63,"table_of_contents":140,"faqs":141,"seo_title":142,"seo_description":67,"update_tm":143,"read_time":144,"preview_page_count":4},4398048949847,"https://ap-avatar.wpscdn.com/avatar/400002536579ef2da7f?_k=1778318612642679267","IDCases 43 (2026) e02459  \nContents lists available at ScienceDirect  \nIDCases  \njournal [homepage:](homepage: www.elsevier.com/locate/idcases)[ www.elsevier.com/locate/idcases](homepage: www.elsevier.com/locate/idcases)  \n| Case report\u003Cbr>Pneumocystis jirovecii pneumonia in a human caused by long-term use of veterinary drug oclacitinib: A case report\u003Cbr>Keisuke Oshima a,* , Ryo Koyama a, Takashi Akimoto a, Toshihiko Nishiokia,\u003Cbr>Tomohito Takeshigea, Junko Watanabe a, Daisuke Usudab, Kazuhisa Takahashi c\u003Cbr>a Department of Respiratory Medicine, Juntendo University Nerima Hospital, 3-1-10 Takanodai, Tokyo, Nerima, Japan\u003Cbr>b Department of Emergency and Critical Care Medicine, Juntendo University Nerima Hospital, 3-1-10 Takanodai, Tokyo, Nerima, Japan c Department of Respiratory Medicine, Juntendo University Graduate School of Medicine, 3-1-3 Hongo, Tokyo, Bunkyo, Japan |  |  |\n| --- | --- | --- |\n| A R T I C L E I N F O |  | A B S T R A C T |\n| Keywords:\u003Cbr>Pneumocystis jirovecii Pneumocystis pneumonia Oclacitinib\u003Cbr>JAK inhibitor Veterinary drug |  | Pneumocystis jirovecii pneumonia (PJP), an opportunistic fungal infection, typically occurs in immunocompromised patients, such as those with human immunodeficiency virus (HIV) infection or those receiving prolonged immunosuppressive therapy. Recently, PJP in non-HIV patients treated with novel immunomodulatory agents, including Janus kinase (JAK) inhibitors, has been increasingly reported. Here, we report a case of PJP in a 53-year-old HIV-negative Japanese man with no recognized immunosuppressive comorbidities. The patient, a veterinarian, had been self-administering oclacitinib (16–64 mg/day), a selective JAK1 inhibitor approved for the treatment of atopic dermatitis in dogs, daily for approximately 2 years to manage atopic dermatitis. He presented with progressive exertional dyspnea and fever. Chest computed tomography revealed bilateral groundglass opacities with patchy consolidations. The diagnosis of PJP was confirmed by polymerase chain reaction of bronchoalveolar lavage fluid and Grocott’s methenamine silver staining of transbronchial lung biopsy specimens. He was initially treated with trimethoprim-sulfamethoxazole and corticosteroids; however, the regimen was switched to atovaquone owing to hepatotoxicity. The patient recovered fully and remained recurrence-free at 1-year follow-up. No other causes of immunosuppression were identified, and oclacitinib use was considered the likely precipitating factor. To our knowledge, this is the first reported case of PJP associated with oclacitinib use in humans. As JAK inhibitors are increasingly being used, clinicians should be aware of their potential to cause opportunistic infections, even with veterinary formulations without approved human indications. |\n\n1. Introduction  \nPneumocystis jirovecii pneumonia (PJP) is an opportunistic fungal infection that primarily affects individuals with impaired cell-mediated immunity, such as patients with human immunodeficiency virus (HIV) infection, hematologic malignancies, or prolonged immunosuppressive therapy. Although the incidence of HIV-associated PJP has declined with the advent of antiretroviral therapy, non-HIV-associated cases in immunocompromised populations have been increasing, particularly among patients receiving novel immunomodulatory agents, including biologics and kinase inhibitors [1].  \nAmong these, Janus kinase (JAK) inhibitors have been recognized asa potential risk factor for opportunistic infections [2]. JAKs are intracellular tyrosine kinases involved in immune regulation, and their inhibition can impair the host defense against pathogens [3]. JAK  \ninhibitors are approved for the treatment of various diseases, including rheumatoid arthritis, atopic dermatitis, ulcerative colitis, and myeloproliferative disorders [4,5]. Herpes zoster is the most frequently reported opportunistic infection associated with JAK inhibitor therapy; however, cases of PJP have also been d","cbCaih3B9Xfu0VvG","https://ap.wps.com/l/cbCaih3B9Xfu0VvG","pdf",3316090,"English","# Introduction\n# Case presentation","[{\"question\":\"Who developed the PJP described in the case report?\",\"answer\":\"A 53-year-old HIV-negative Japanese man, working as a veterinarian, presented with progressive exertional dyspnea and fever after a long period of oclacitinib self-administration.\"},{\"question\":\"How was PJP diagnosed in this patient?\",\"answer\":\"Diagnosis was confirmed using polymerase chain reaction of bronchoalveolar lavage fluid and Grocott’s methenamine silver staining of transbronchial lung biopsy specimens.\"},{\"question\":\"What treatment led to recovery, and did the patient have recurrence?\",\"answer\":\"He was initially treated with trimethoprim-sulfamethoxazole and corticosteroids, then switched to atovaquone due to hepatotoxicity. The patient fully recovered and remained recurrence-free at 1-year follow-up.\"}]","Pneumocystis jirovecii pneumonia in a human caused by long-term use of veterinary drug oclacitinib - A case report | PDF",1790703322,13]