Objectives: To determine if the clinical characteristics of children with gastroenteritis and influenza identified in their stool differ from those whose stool was influenza-negative.
Methods: 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.
Results: 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.
Conclusions: 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.