{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,8]],"date-time":"2026-09-08T11:09:38Z","timestamp":1788865778584,"version":"build-2803163510"},"reference-count":51,"publisher":"Cambridge University Press (CUP)","license":[{"start":{"date-parts":[[2026,9,8]],"date-time":"2026-09-08T00:00:00Z","timestamp":1788825600000},"content-version":"unspecified","delay-in-days":250,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0"}],"content-domain":{"domain":["cambridge.org"],"crossmark-restriction":true},"short-container-title":["Epidemiol. Infect."],"published-print":{"date-parts":[[2026]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:p>\n                    Encephalitis lethargica (EL), also known as the \u2018European Sleeping Sickness\u2019, emerged in Europe around 1916, with Sweden reporting the highest global incidence rate in 1921. This study investigates regional variations in EL incidence across Sweden between 1920 and 1930, with a particular focus on the major outbreak in 1921. Using data from\n                    <jats:italic>Public Health in Sweden<\/jats:italic>\n                    , incidence rates were calculated for all Swedish regions, revealing a disproportionate concentration of cases in central and northern areas, especially in the parish of Vilhelmina in V\u00e4sterbotten. To contextualize this outbreak, monthly disease data from the\n                    <jats:italic>Annual Reports of the Chief Provincial Doctor in V\u00e4sterbotten<\/jats:italic>\n                    were analysed to compare the local disease panorama. Notably, preceding the first EL cases in Vilhelmina, influenza\/H1N1 and mumps were frequently reported. Although the aetiology of EL remains unresolved, the presence of a preceding influenza and mumps epidemic is consistent with the dual-pathogen hypothesis, suggesting that interactions between infectious agents may have contributed to the emergence of EL in local hotspots.\n                  <\/jats:p>","DOI":"10.1017\/s0950268826102003","type":"journal-article","created":{"date-parts":[[2026,9,8]],"date-time":"2026-09-08T10:36:03Z","timestamp":1788863763000},"update-policy":"https:\/\/doi.org\/10.1017\/policypage","source":"Crossref","is-referenced-by-count":0,"title":["Encephalitis lethargica in Sweden, 1920\u20131930: national incidence and the 1921 outbreak in northern Sweden"],"prefix":"10.1017","volume":"154","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-7406-7836","authenticated-orcid":false,"given":"Lena","family":"Karlsson","sequence":"first","affiliation":[{"name":"Ume\u00e5 University"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Erling","family":"H\u00e4ggstr\u00f6m Gunfridsson","sequence":"additional","affiliation":[{"name":"Ume\u00e5 University"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"56","published-online":{"date-parts":[[2026,9,8]]},"reference":[{"key":"S0950268826102003_r14","unstructured":"[14] Stranger, D (1925) Enchephalitis lethargica and its after effects. Annexe Thesis Digitisation Project 2017 Block 11."},{"key":"S0950268826102003_r2","doi-asserted-by":"publisher","DOI":"10.1007\/s00702-009-0295-9"},{"key":"S0950268826102003_r5","doi-asserted-by":"publisher","DOI":"10.1177\/03946320231154997"},{"key":"S0950268826102003_r50","doi-asserted-by":"publisher","DOI":"10.1016\/S1474-4422(23)00083-2"},{"key":"S0950268826102003_r4","doi-asserted-by":"publisher","DOI":"10.1001\/archneur.1968.00470330114013"},{"key":"S0950268826102003_r12","doi-asserted-by":"publisher","DOI":"10.1093\/shm\/hkae052"},{"key":"S0950268826102003_r35","doi-asserted-by":"publisher","DOI":"10.1093\/braincomms\/fcae347"},{"key":"S0950268826102003_r43","unstructured":"[43] Medicinalstyrelsen, K. (1920) Allm\u00e4n h\u00e4lso- och sjukv\u00e5rd: [Public health in Sweden]. Allm\u00e4n h\u00e4lso- och sjukv\u00e5rd = [Public health in Sweden]."},{"key":"S0950268826102003_r39","volume-title":"Om Encephalitis Lethargica: Encephalomyelitis Epidemica","author":"Antoni","year":"1921"},{"key":"S0950268826102003_r1","doi-asserted-by":"publisher","DOI":"10.1093\/brain\/awx177"},{"key":"S0950268826102003_r13","doi-asserted-by":"publisher","DOI":"10.1016\/j.pnpbp.2021.110276"},{"key":"S0950268826102003_r18","first-page":"449","article-title":"Epidemic encephalitis (Encephalitis lethargica)","volume":"11","author":"Strauss","year":"1921","journal-title":"International Journal of Public Health"},{"key":"S0950268826102003_r7","doi-asserted-by":"publisher","DOI":"10.1093\/brain\/awh008"},{"key":"S0950268826102003_r31","doi-asserted-by":"publisher","DOI":"10.1016\/S0140-6736(00)53519-3"},{"key":"S0950268826102003_r36","doi-asserted-by":"publisher","DOI":"10.1016\/S0140-6736(22)00383-X"},{"key":"S0950268826102003_r44","unstructured":"[44] Statistiska centralbyr\u00e5n. Folkm\u00e4ngden inom administrativa omr\u00e5den den 31 december, 1910\u20131961. Yearly publications. Stockholm: Statistiska centralbyr\u00e5n (SCB)."},{"key":"S0950268826102003_r28","doi-asserted-by":"publisher","DOI":"10.1136\/jnnp.2006.106450"},{"key":"S0950268826102003_r40","volume-title":"Kunskap Och Kontroll: den Svenska Befolkningsstatistikens Historia","author":"Sk\u00f6ld","year":"2001"},{"key":"S0950268826102003_r45","volume-title":"Historisk Statistik f\u00f6r Sverige. [Population 1720\u20131967] D. 1 Befolkning 1720\u20131967","year":"1969"},{"key":"S0950268826102003_r49","unstructured":"[49] \u00c5man, M (1990) Spanska sjukan: den svenska epidemin 1918\u20131920 och dess internationella bakgrund [Doctoral thesis, monograph]. Uppsala: Acta Universitatis Upsaliensis."},{"key":"S0950268826102003_r29","doi-asserted-by":"publisher","DOI":"10.1001\/archneurpsyc.1929.02220040122013"},{"key":"S0950268826102003_r19","first-page":"648","article-title":"Discussion on Encephalitis lethargica","volume":"2","author":"Bramwell","year":"1921","journal-title":"The British Medical Journal"},{"key":"S0950268826102003_r21","doi-asserted-by":"publisher","DOI":"10.1016\/j.pediatrneurol.2007.04.012"},{"key":"S0950268826102003_r41","first-page":"121","article-title":"F\u00f6rs\u00f6k att utr\u00f6na den s.k. lethargiska encephalitens spridningss\u00e4tt. F\u00f6rutl\u00f6pande meddelande, inl\u00e4mnat som rapport till Kungl. Medicinalstyrelsen den 15 febr. 1921","volume":"18","author":"Kling","year":"1921","journal-title":"Svenska L\u00e4kartidningen"},{"key":"S0950268826102003_r3","doi-asserted-by":"publisher","DOI":"10.1093\/jnen\/60.7.696"},{"key":"S0950268826102003_r17","volume-title":"Manifestations tardives de l\u2019enc\u00e9phalite \u00e9pid\u00e9mique","author":"Levy","year":"1922"},{"key":"S0950268826102003_r9","doi-asserted-by":"publisher","DOI":"10.1016\/j.clineuro.2020.106065"},{"key":"S0950268826102003_r16","first-page":"731","article-title":"Lumleian lectures","volume":"1","author":"Hall","year":"1923","journal-title":"Lancet"},{"key":"S0950268826102003_r23","volume-title":"Awakenings","author":"Sacks","year":"1982"},{"key":"S0950268826102003_r11","doi-asserted-by":"publisher","DOI":"10.1016\/j.mehy.2020.110420"},{"key":"S0950268826102003_r48","unstructured":"[48] P\u00e5ssjukan p\u00e5 turn\u00e9 [Mumps on tour] (1921) Arbetet. 1921-01-13."},{"key":"S0950268826102003_r20","first-page":"18","article-title":"Epidemic encephalitis (Encephalitis lethargica) in childhood: With special reference to the changes in the Cerebro-spinal fluid","volume":"95","author":"Findlay","year":"1921","journal-title":"Glasgow Medical Journal"},{"key":"S0950268826102003_r15","doi-asserted-by":"publisher","DOI":"10.1007\/978-1-4939-0384-9"},{"key":"S0950268826102003_r42","doi-asserted-by":"publisher","DOI":"10.1017\/S0950268808001891"},{"key":"S0950268826102003_r27","doi-asserted-by":"publisher","DOI":"10.1093\/brain\/110.1.19"},{"key":"S0950268826102003_r10","doi-asserted-by":"publisher","DOI":"10.12659\/MSM.931447"},{"key":"S0950268826102003_r34","doi-asserted-by":"publisher","DOI":"10.1186\/1471-2334-12-136"},{"key":"S0950268826102003_r33","doi-asserted-by":"publisher","DOI":"10.1007\/s10072-023-07053-8"},{"key":"S0950268826102003_r37","volume-title":"\u201cDie Encephalitis Lethargica, Ihre Nachkrankheiten Und Ihre","author":"Von Economo","year":"1929"},{"key":"S0950268826102003_r25","doi-asserted-by":"publisher","DOI":"10.1016\/S0140-6736(82)90820-0"},{"key":"S0950268826102003_r51","doi-asserted-by":"publisher","DOI":"10.1016\/S0140-6736(26)00363-6"},{"key":"S0950268826102003_r6","doi-asserted-by":"publisher","DOI":"10.1001\/archneur.1965.00460270003001"},{"key":"S0950268826102003_r26","doi-asserted-by":"publisher","DOI":"10.1136\/bmj.1.4976.1141"},{"key":"S0950268826102003_r24","doi-asserted-by":"publisher","DOI":"10.1177\/003591573703100101"},{"key":"S0950268826102003_r30","doi-asserted-by":"publisher","DOI":"10.1136\/bmj.1.4772.1317"},{"key":"S0950268826102003_r22","doi-asserted-by":"publisher","DOI":"10.1016\/S1474-4422(18)30501-5"},{"key":"S0950268826102003_r32","doi-asserted-by":"publisher","DOI":"10.1093\/infdis\/41.4.257"},{"key":"S0950268826102003_r8","first-page":"745","volume-title":"Handbook of Clinical Neurology","author":"Berger","year":"2014"},{"key":"S0950268826102003_r38","first-page":"181","volume-title":"Smittor, Epidemisjukhus Och infektionsl\u00e4kare I Sydsverige","author":"Eitrem","year":"2012"},{"key":"S0950268826102003_r46","doi-asserted-by":"publisher","DOI":"10.1093\/jnen\/60.7.663"},{"key":"S0950268826102003_r47","unstructured":"[47] Statistiska centralbyr\u00e5n (1920) D\u00f6dsorsaker: [Causes of death]. Stockholm: Statistiska centralbyr\u00e5n (SCB)."}],"container-title":["Epidemiology and Infection"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.cambridge.org\/core\/services\/aop-cambridge-core\/content\/view\/S0950268826102003","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,9,8]],"date-time":"2026-09-08T10:36:07Z","timestamp":1788863767000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.cambridge.org\/core\/product\/identifier\/S0950268826102003\/type\/journal_article"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026]]},"references-count":51,"alternative-id":["S0950268826102003"],"URL":"https:\/\/doi.org\/10.1017\/s0950268826102003","relation":{},"ISSN":["0950-2688","1469-4409"],"issn-type":[{"value":"0950-2688","type":"print"},{"value":"1469-4409","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026]]},"assertion":[{"value":"\u00a9 The Author(s), 2026. Published by Cambridge University Press","name":"copyright","label":"Copyright","group":{"name":"copyright_and_licensing","label":"Copyright and Licensing"}},{"value":"This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (http:\/\/creativecommons.org\/licenses\/by\/4.0), which permits unrestricted re-use, distribution and reproduction, provided the original article is properly cited.","name":"license","label":"License","group":{"name":"copyright_and_licensing","label":"Copyright and Licensing"}},{"value":"This content has been made available to all.","name":"free","label":"Free to read"}],"article-number":"e114"}}