{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,29]],"date-time":"2026-07-29T12:04:59Z","timestamp":1785326699870,"version":"3.55.0"},"reference-count":15,"publisher":"Wiley","issue":"1","license":[{"start":{"date-parts":[[2026,7,29]],"date-time":"2026-07-29T00:00:00Z","timestamp":1785283200000},"content-version":"vor","delay-in-days":209,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"},{"start":{"date-parts":[[2026,1,1]],"date-time":"2026-01-01T00:00:00Z","timestamp":1767225600000},"content-version":"tdm","delay-in-days":0,"URL":"http:\/\/doi.wiley.com\/10.1002\/tdm_license_1.1"}],"content-domain":{"domain":["onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Case Reports in Medicine"],"published-print":{"date-parts":[[2026,1]]},"abstract":"<jats:p>This case highlights the diagnostic challenges of managing a patient who initially presented with a fever of unknown source and subsequently met the criteria for fever of unknown origin (FUO) after more than 3\u2009weeks of persistent fever despite an extensive diagnostic workup in a resource\u2010limited tertiary hospital within Brazil\u2019s public health system. A man in his sixth decade presented with prolonged high\u2010grade fever and severe lower\u2010limb myalgia, initially raising suspicion for leptospirosis due to rural exposure and occupational history. Extensive evaluation\u2014including blood cultures, serologies, and imaging screening\u2014revealed no infectious or malignant cause. Persistent neutrophilic leukocytosis, marked hyperferritinemia, and elevated inflammatory markers suggested a systemic autoinflammatory disorder. A trial of low\u2010dose prednisone produced partial improvement, and rheumatology consultation supported the diagnosis of adult\u2010onset Still disease (AOSD) based on Yamaguchi criteria. Corticosteroid escalation resulted in the rapid resolution of fever and myalgia. This case underscores the importance of structured reasoning, systematic exclusion of common causes, and careful attention to laboratory patterns for timely diagnosis in resource\u2010limited settings.<\/jats:p>","DOI":"10.1155\/carm\/6925896","type":"journal-article","created":{"date-parts":[[2026,7,29]],"date-time":"2026-07-29T11:17:15Z","timestamp":1785323835000},"update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Acute Adult\u2010Onset Still Disease Presenting as Fever of Unknown Origin and Severe Myalgia in a Resource\u2010Limited Tertiary Hospital in Brazil"],"prefix":"10.1155","volume":"2026","author":[{"ORCID":"https:\/\/orcid.org\/0009-0001-4309-4583","authenticated-orcid":false,"given":"Breno Bopp","family":"Antonello","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0003-1678-3142","authenticated-orcid":false,"given":"Cain\u00e3 Gon\u00e7alves","family":"Rodrigues","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3334-2130","authenticated-orcid":false,"given":"Giovanna Giovacchini dos","family":"Santos","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0001-1471-1028","authenticated-orcid":false,"given":"Laura Grespan","family":"Dill","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6323-2234","authenticated-orcid":false,"given":"Paulo Victor Zattar","family":"Ribeiro","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"311","published-online":{"date-parts":[[2026,7,29]]},"reference":[{"key":"e_1_2_15_1_2","doi-asserted-by":"publisher","DOI":"10.1093\/ofid\/ofaa132"},{"key":"e_1_2_15_2_2","doi-asserted-by":"publisher","DOI":"10.1097\/md.0b013e31802fe858"},{"key":"e_1_2_15_3_2","doi-asserted-by":"publisher","DOI":"10.1371\/journal.pntd.0007270"},{"key":"e_1_2_15_4_2","doi-asserted-by":"publisher","DOI":"10.1371\/journal.pntd.0009256"},{"key":"e_1_2_15_5_2","doi-asserted-by":"publisher","DOI":"10.1590\/1413-812320172212.14112016"},{"key":"e_1_2_15_6_2","article-title":"Clinical Diagnosis and Assessment of Severity of Confirmed Dengue Infections in Vietnamese Children: Is the World Health Organization Classification System Helpful?","volume":"70","author":"Phuong CX","year":"2025","journal-title":"The American Journal of Tropical Medicine and Hygiene"},{"key":"e_1_2_15_7_2","doi-asserted-by":"publisher","DOI":"10.1093\/cid\/ciy1083"},{"key":"e_1_2_15_8_2","article-title":"EULAR\/PReS Recommendations for the Diagnosis and Management of Still\u2019s Disease, Comprising Systemic Juvenile Idiopathic Arthritis and Adult-Onset Still\u2019s Disease","volume":"24","author":"Fautrel B.","year":"2024","journal-title":"Annals of the Rheumatic Diseases"},{"key":"e_1_2_15_9_2","first-page":"1608","article-title":"Still\u2019s Disease in a 72-year-old Man","volume":"20","author":"Uson","year":"2025","journal-title":"Journal of Rheumatology"},{"key":"e_1_2_15_10_2","article-title":"Preliminary Criteria for Classification of Adult Still\u2019s Disease","volume":"19","author":"Yamaguchi","year":"2025","journal-title":"Journal of Rheumatology"},{"key":"e_1_2_15_11_2","article-title":"Diagnostic Value of Ferritin and Glycosylated Ferritin in Adult Onset Still\u2019s Disease","volume":"28","author":"Fautrel B.","year":"2025","journal-title":"Journal of Rheumatology"},{"key":"e_1_2_15_12_2","doi-asserted-by":"publisher","DOI":"10.1136\/ard.51.5.683"},{"key":"e_1_2_15_13_2","doi-asserted-by":"publisher","DOI":"10.1038\/s41584-018-0081-x"},{"key":"e_1_2_15_14_2","doi-asserted-by":"publisher","DOI":"10.7759\/cureus.52605"},{"key":"e_1_2_15_15_2","volume-title":"Q Fever. 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