title: Prevalence of gastrointestinal symptoms in patients with influenza, clinical significance, and pathophysiology of human influenza viruses in faecal samples: what do we know?
abstract: This review provides for the first time an assessment of the current understanding about the occurrence and the clinical significance of gastrointestinal (GI) symptoms in influenza patients, and their correlation with the presence of human influenza viruses in stools of patients with confirmed influenza virus infection. Studies exploring how human influenza viruses spread to the patient's GI tract after a primary respiratory infection have been summarized. We conducted a systematic search of published peer-reviewed literature up to June 2015 with regard to the above-mentioned aspects, focusing on human influenza viruses (A(H1N1), A(H1N1)pdm09, A(H3N2), and B). Forty-four studies were included in this systematic review and meta-analysis. The pooled prevalence of any digestive symptoms ranged from 30.9% (95% CI, 9.8 to 57.5; I(2) = 97.5%) for A(H1N1)pdm09 to 2.8% (95% CI, 0.6 to 6.5; I(2) = 75.4%) for A(H1N1). The pooled prevalence of influenza viruses in stool was 20.6% (95% CI, 8.9 to 35.5; I(2) = 96.8%), but their correlation with GI symptoms has rarely been explored. The presence of viral RNA in stools because of haematogenous dissemination to organs via infected lymphocytes is likely, but the potential to cause direct intestinal infection and faecal-oral transmission warrants further investigation. This review highlights the gaps in our knowledge, and the high degree of uncertainty about the prevalence and significance of GI symptoms in patients with influenza and their correlation with viral RNA positivity in stool because of the high level of heterogeneity among studies.
authors.affiliation: EA 7310, laboratory of virology, University of Corsica-Inserm, 20250, Corte, France. minodier@univ-corse.fr.
authors.forename: Laetitia
authors.initials: L
authors.lastname: Minodier
authors.affiliation: Aix Marseille Université, IRD French Institute of Research for Development, INSERM U1207, EHESP French School of Public Health, EPV UMR_D 190 "Emergence des Pathologies Virales", & IHU Méditerranée Infection, APHM Public Hospitals of Marseille, Marseille, France. remi.charrel@univ-amu.fr.
authors.forename: Remi N
authors.initials: RN
authors.lastname: Charrel
authors.affiliation: Unité EPVO, Institut Pasteur, Paris-UMR CNRS 3569-Université Paris Diderot, Paris Sorbonne Cité, Cellule Pasteur, Paris, France. pierre-emmanuel.ceccaldi@pasteur.fr.
authors.forename: Pierre-Emmanuel
authors.initials: PE
authors.lastname: Ceccaldi
authors.affiliation: Unit of Molecular Genetics of RNA viruses, Institut Pasteur-UMR CNRS 3569-Université Paris Diderot-Sorbonne Paris Cité, Paris, France. sylvie.van-der-werf@pasteur.fr.|Coordinating Center of the National Reference Center for influenza viruses, National Influenza Center (Northern-France), Institut Pasteur, Paris, France. sylvie.van-der-werf@pasteur.fr.
authors.forename: Sylvie
authors.initials: S
authors.lastname: van der Werf
authors.affiliation: Sorbonne Universités, UPMC Univ Paris 06, UMR_S 1136, Paris, France. thierry.blanchon@upmc.fr.|INSERM, UMR_S 1136, Paris, France. thierry.blanchon@upmc.fr.
authors.forename: Thierry
authors.initials: T
authors.lastname: Blanchon
authors.affiliation: INSERM, UMR_S 1136, Paris, France. thomas.hanslik@aphp.fr.|Université Versailles Saint Quentin en Yvelines, UFR de Médecine Paris-Ile-de-France-Ouest, 9 boulevard d'Alembert, 78280, Guyancourt, France. thomas.hanslik@aphp.fr.|Service de médecine interne, Hôpital Ambroise Paré, Assistance Publique-Hôpitaux de Paris, 92100, Boulogne Billancourt, France. thomas.hanslik@aphp.fr.
authors.forename: Thomas
authors.initials: T
authors.lastname: Hanslik
authors.affiliation: EA 7310, laboratory of virology, University of Corsica-Inserm, 20250, Corte, France. falchi@univ-corse.fr.
authors.forename: Alessandra
authors.initials: A
authors.lastname: Falchi
mesh_terms: D005243:Feces / Q000821:virology*; D005767:Gastrointestinal Diseases / Q000453:epidemiology* / Q000209:etiology* / Q000473:pathology; D006801:Humans; D007251:Influenza, Human / Q000150:complications* / Q000473:pathology*; D009975:Orthomyxoviridae / Q000302:isolation & purification*; D015995:Prevalence