Influenza virus detection in the stool of children with acute gastroenteritis.

To determine if the clinical characteristics of children with gastroenteritis and influenza identified in their stool differ from those whose stool was influenza-negative. Children <18-years with gastroenteritis whose stool tested negative for enteropathogen were tested for influenza in stool. The clinical features between influenza-positive and influenza-negative gastroenteritis cases were compared. Stools from controls without infection were also tested for influenza. Among the 440 gastroenteritis cases, those who were influenza test-positive were older [median age 4.0 (IQR: 2.3, 5.5) vs. 1.5 (IQR: 0.5, 4.0) years; P = 0.008], more likely to present in fall or winter (92.3 % vs. 48.0 %; P = 0.001), be febrile (84.6 % vs. 30.6 %; P < 0.001), have respiratory symptoms (91.7 % vs. 44.8 %; P = 0.002), have dehydration [median Clinical Dehydration Scale score: 4 (IQR: 1.5, 4.5) vs. 2 (IQR: 0, 3); P = 0.034], and have higher Modified Vesikari Scale scores [median: 13 (IQR: 10.5, 14.0) vs. 10 (IQR: 9.0, 13.0); P = 0.044], than those who tested negative. Thirteen gastroenteritis cases (13/440; 3.0 %) including one child without respiratory symptoms vs. one control (1/250; 0.4 %) were influenza stool positive. Fever, respiratory symptoms, more severe illness, and older age were more common in children with gastroenteritis with influenza detected in stool, compared to those tested negative.