Comparision of epidemiological and clinical features between moderate and severe Japanese encephalitis in children in Shanghai

Objective To understand the epidemiological and clinical features of moderate and severe Japanese encephalitis (JE) in pediatric inpatients in Shanghai and assess the risk factors associated with the severity and prognosis of JE.Methods The clinical data from pediatric JE cases who acquired JE infection in Shanghai during 2002-2011 were retrospectively analyzed. JE was laboratory-confirmed based on the positive JEV-specific immunoglobulin M detection in serum and/or cerebral spinal fluid in clinical cases.Results A total of 73 children confirmed with JE were included in this study. the male-to-female ratio was 2.3:1 and the mean age was 5.1 years; 65 (89%) were migrant children; 12 (16.4%) had reliable records of JE vaccination; 69 (94.5%) lived in rural or suburban areas. All JE cases in Shanghai occurred in July and August with more severe cases occurring in early July. All JE cases had fever, followed by neck rigidity (82.2%), seizure (76.7%), headache (75.3%), vomiting (74%) and coma (47.9%). Six (8.2%) cases had secondary respiratory failure, and 3 (4.1%) deceased. Twenty (27.4%) had various disability at hospital discharge. The rates of disability or mortality at hospital discharge in moderate and severe JE were 13.0% and 84.2% (χ2=33.06,P0.000 1). The median value of serum creatine kinase (CK) was significant higher in severe cases than in moderate cases (465 verse 105 U·L-1, Z=-3.173,P=0.001). The independent risk factors associated with the poor outcomes of JE at hospital discharge included multiple seizures (OR=29.3), coma (OR=253.6),living near pigs farms (OR=16.9) and serum CK 200 U·L-1 (OR=0.01).Conclusions The clinical classification of JE severity is useful to guide the appropriate management and predict the prognosis. Elevated serum CK is an important biochemical predictor for severe JE. Multiple seizures, coma, living near pig farms and serum CK200 U·L-1 are the independent risk factors associated with severe JE and poor outcome. Reinforcement of JE immunization among the migrant children is crucial to reduce the morbidity and sequelae of JE in Shanghai.