Abstracts

Rationale: Norovirus has gradually increased in benign convulsions with mild gastroenteritis (CwG) since introduction of rotavirus vaccine. In our previous study, rotavirus positivity dropped from 40.54% in 5 years before February 2010 to 16% in 5 years after March 2010 when rotavirus vaccination rate reached up to more than 50% [1]. We investigated the incidence of norovirus-associated CwG in the recent 3 years and compared norovirus-associated CwG with rotavirus-associated CwG. Methods: The medical records of 46 CwG patients admitted in our hospital between March 2014 and February 2017 were reviewed. Viruses isolated from CwG patients and the performance rate of stool virus tests were reviewed. For comparison of norovirus-associated CwG with rotavirus-associated CwG, we additionally included our previous data between March 2005 and February 2014 when rotavirus was prevalent [1]. Data for clinical characteristics (age, gender, seasonal distribution, incidence of enteric symptom, and the interval time between enteric symptom-onset and seizure-onset), seizure characteristics (frequency, duration, type and EEGs) and laboratory findings (blood cell counts, electrolytes, and blood lactate) were collected. Results: Stool viruses were checked in 95.7% (44 patients) and were isolated in 77.3% (34 patients). Norovirus, type 2 were isolated in 30 patients (68.2% of 44 patients), and rotavirus and adenovirus were respectively found in 2 patients (4.5%). The year-incidence of norovirus-associated CwG was 83.3% (10 among 12 patients) in 2014, 58.8% (10 among 17 patients) in 2015, and 66.7% (10 among 15 patients) in 2016, which were not significantly different between years (p=0.37). Comparison of norovirus-associated CwG (total 47 patients; 17 patients from our previous study; 19.08±7.43 months of age) with rotavirus-associated CwG (total 25 patients; 23 patients from our previous study; 18.25±5.67 months of age) showed differences for spring season incidence, vomiting incidence, the interval time, and platelet counts. Norovirus-associated CwG was less prevalent in the spring (from March to May) than rotavirus-associated CwG (12.8% vs. 36.0%; p=0.022), although either CwG was the most prevalent in the winter (66.0% vs. 44%; p=0.074). In norovirus-assocaited CwG, vomiting was more prevalent (95.7% vs. 84%; p=0.031) and the interval times were shorter (1.95±1.05 days vs. 2.64±1.19 days; p=0.014). Frequent seizures (more than 5 times) were observed only in norovirus-associated CwG (12.8%; 6 patients; p=0.064). Platelet counts were higher in norovirus-associated CwG than rotavirus-associated CwG (320,560±87,630/mm3 vs. 266,640±97,320/mm3; p=0.020). Conclusions: The most common viral pathogen of CwG was norovirus in recent 3 years, which incidence was 68.2%. In comparison with rotavirus-associated CwG, norovirus-associated CwG was less frequent in the spring season, more frequently seen with vomiting, observed in shorter interval from enteric symptom-onset and presented with higher platelet counts.References1. Park SH, Kim YO, Kim HK, et al. Incidence of benign convulsions with mild gastroenteritis after introduction of rotavirus vaccine. Brain Dev. 2015;37:625–30. Funding: There is no funding to be clarified.