Survey of rotavirus-associated severe complications in Aichi Prefecture

Background: Rotavirus can, rarely, cause severe complications such as encephalopathy/encephalitis, myocarditis, sudden death, urinary stone, and gastrointestinal (GI) bleeding; and the incidence of these severe complications remains unclear. Additionally, it has not been determined whether rotavirus (RV) vaccine could reduce cases of severe complications or not. Methods: A two-part questionnaire was designed to determine the number and clinical features of severe complications between 1 September 2008 and 31 August 2015, including the observation periods before and after RV vaccine introduction in Aichi Prefecture. Results: Twenty-four cases of encephalitis/encephalopathy, eight cases of sudden death, three cases of urinary tract stone, and three cases of GI bleeding were reported during the 2008/2009 season and the 2012/2013 seasons. Although five cases of encephalitis/encephalopathy were reported, no other cases of severe complications were reported during the 2013/2014 and 2014/2015 seasons. No age difference was noted according to type of complication. Although onset of encephalitis/encephalopathy and of sudden death was around day 2 of illness, that of urinary tract stone and GI bleeding was slightly later (day 6 and day 4). In addition to the eight sudden deaths, fatal outcome was also noted in four cases (13.8%) of encephalitis/encephalopathy, and in one case of GI bleeding. Conclusion: According to the questionnaire survey in Aichi Prefecture, the incidence of the four severe RV-associated complications appears to have declined as the vaccination rate has increased.