National surveillance of influenza-associated encephalopathy in Japan over six years, before and during the 2009-2010 influenza pandemic.

Influenza-associated encephalopathy (IAE) is a serious complication of influenza and is reported most frequently in Japan. This paper presents an assessment of the epidemiological characteristics of influenza A (H1N1) 2009-associated encephalopathy in comparison to seasonal IAE, based on Japanese na...

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Autores principales:	Yoshiaki Gu, Tomoe Shimada, Yoshinori Yasui, Yuki Tada, Mitsuo Kaku, Nobuhiko Okabe
Formato:	article
Lenguaje:	EN
Publicado:	Public Library of Science (PLoS) 2013
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/62045b1cf70642f3a134317e87c5c9ee
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spelling	oai:doaj.org-article:62045b1cf70642f3a134317e87c5c9ee2021-11-18T08:00:29ZNational surveillance of influenza-associated encephalopathy in Japan over six years, before and during the 2009-2010 influenza pandemic.1932-620310.1371/journal.pone.0054786https://doaj.org/article/62045b1cf70642f3a134317e87c5c9ee2013-01-01T00:00:00Zhttps://www.ncbi.nlm.nih.gov/pmc/articles/pmid/23355899/?tool=EBIhttps://doaj.org/toc/1932-6203Influenza-associated encephalopathy (IAE) is a serious complication of influenza and is reported most frequently in Japan. This paper presents an assessment of the epidemiological characteristics of influenza A (H1N1) 2009-associated encephalopathy in comparison to seasonal IAE, based on Japanese national surveillance data of influenza-like illness (ILI) and IAE during flu seasons from 2004-2005 through 2009-2010. In each season before the pandemic, 34-55 IAE cases (mean 47.8; 95% confidence interval: 36.1-59.4) were reported, and these cases increased drastically to 331 during the 2009 pandemic (6.9-fold the previous seasons). Of the 331 IAE cases, 322 cases were reported as influenza A (H1N1) 2009-associated encephalopathy. The peaks of IAE were consistent with the peaks of the influenza epidemics and pandemics. A total of 570 cases of IAE (seasonal A, 170; seasonal B, 50; influenza A (H1N1) 2009, 322; unknown, 28) were reported over six seasons. The case fatality rate (CFR) ranged from 4.8 to 18.2% before the pandemic seasons and 3.6% in the 2009 pandemic season. The CFR of pandemic-IAE was 3.7%, which is lower than that of influenza A-/B-associated encephalopathy (12.9%, p<0.001; 14.0%, p = 0.002; respectively). The median age of IAE was 7 years during the pandemic, which is higher than that of influenza A-/B-associated encephalopathy (4, p<0.001; 4.5, p = 0.006; respectively). However, the number of pandemic-IAE cases per estimated ILI outpatients peaked in the 0-4-year age group and data both before and during the pandemic season showed a U-shape pattern. This suggests that the high incidence of influenza infection in the 0-4 year age group may lead to a high incidence of IAE in the same age group in a future influenza season. Further studies should include epidemiologic case definitions and clinical details of IAE to gain a more accurate understanding of the epidemiologic status of IAE.Yoshiaki GuTomoe ShimadaYoshinori YasuiYuki TadaMitsuo KakuNobuhiko OkabePublic Library of Science (PLoS)articleMedicineRScienceQENPLoS ONE, Vol 8, Iss 1, p e54786 (2013)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q Yoshiaki Gu Tomoe Shimada Yoshinori Yasui Yuki Tada Mitsuo Kaku Nobuhiko Okabe National surveillance of influenza-associated encephalopathy in Japan over six years, before and during the 2009-2010 influenza pandemic.
description	Influenza-associated encephalopathy (IAE) is a serious complication of influenza and is reported most frequently in Japan. This paper presents an assessment of the epidemiological characteristics of influenza A (H1N1) 2009-associated encephalopathy in comparison to seasonal IAE, based on Japanese national surveillance data of influenza-like illness (ILI) and IAE during flu seasons from 2004-2005 through 2009-2010. In each season before the pandemic, 34-55 IAE cases (mean 47.8; 95% confidence interval: 36.1-59.4) were reported, and these cases increased drastically to 331 during the 2009 pandemic (6.9-fold the previous seasons). Of the 331 IAE cases, 322 cases were reported as influenza A (H1N1) 2009-associated encephalopathy. The peaks of IAE were consistent with the peaks of the influenza epidemics and pandemics. A total of 570 cases of IAE (seasonal A, 170; seasonal B, 50; influenza A (H1N1) 2009, 322; unknown, 28) were reported over six seasons. The case fatality rate (CFR) ranged from 4.8 to 18.2% before the pandemic seasons and 3.6% in the 2009 pandemic season. The CFR of pandemic-IAE was 3.7%, which is lower than that of influenza A-/B-associated encephalopathy (12.9%, p<0.001; 14.0%, p = 0.002; respectively). The median age of IAE was 7 years during the pandemic, which is higher than that of influenza A-/B-associated encephalopathy (4, p<0.001; 4.5, p = 0.006; respectively). However, the number of pandemic-IAE cases per estimated ILI outpatients peaked in the 0-4-year age group and data both before and during the pandemic season showed a U-shape pattern. This suggests that the high incidence of influenza infection in the 0-4 year age group may lead to a high incidence of IAE in the same age group in a future influenza season. Further studies should include epidemiologic case definitions and clinical details of IAE to gain a more accurate understanding of the epidemiologic status of IAE.
format	article
author	Yoshiaki Gu Tomoe Shimada Yoshinori Yasui Yuki Tada Mitsuo Kaku Nobuhiko Okabe
author_facet	Yoshiaki Gu Tomoe Shimada Yoshinori Yasui Yuki Tada Mitsuo Kaku Nobuhiko Okabe
author_sort	Yoshiaki Gu
title	National surveillance of influenza-associated encephalopathy in Japan over six years, before and during the 2009-2010 influenza pandemic.
title_short	National surveillance of influenza-associated encephalopathy in Japan over six years, before and during the 2009-2010 influenza pandemic.
title_full	National surveillance of influenza-associated encephalopathy in Japan over six years, before and during the 2009-2010 influenza pandemic.
title_fullStr	National surveillance of influenza-associated encephalopathy in Japan over six years, before and during the 2009-2010 influenza pandemic.
title_full_unstemmed	National surveillance of influenza-associated encephalopathy in Japan over six years, before and during the 2009-2010 influenza pandemic.
title_sort	national surveillance of influenza-associated encephalopathy in japan over six years, before and during the 2009-2010 influenza pandemic.
publisher	Public Library of Science (PLoS)
publishDate	2013
url	https://doaj.org/article/62045b1cf70642f3a134317e87c5c9ee
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National surveillance of influenza-associated encephalopathy in Japan over six years, before and during the 2009-2010 influenza pandemic.

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