title: Prevalence, risk factors for infection and subtype distribution of the intestinal parasite Blastocystis sp. from a large-scale multi-center study in France.
abstract: BACKGROUND
  Blastocystis sp. is the most common intestinal parasite of humans. Despite its potential public health impact, epidemiological data regarding the prevalence and molecular subtype distribution of Blastocystis sp. in Europe are rarely reported. Therefore, the first multi-center epidemiological survey performed in Europe was conducted in France to diagnose and subtype Blastocystis sp. and to identify risk factors for infection.
  
  
  METHODS
  Stool samples from 788 patients were collected either in summer or winter in 11 hospitals throughout France together with patient data. All stool samples were tested for the presence of Blastocystis sp. by quantitative PCR targeting the SSU rDNA gene. Positive samples were sequenced to determine the distribution of the subtypes in our cohort. Statistical analyses were performed to identify potential risk factors for infection.
  
  
  RESULTS
  Using quantitative PCR, the overall prevalence of Blastocystis sp. was shown to reach 18.1 %. The prevalence was significantly higher in summer (23.2 %) than in winter (13.7 %). Travellers or subjects infected with other enteric parasites were significantly more infected by Blastocystis sp. than non-travellers or subjects free of other enteric parasites, respectively. Different age-related epidemiological patterns were also highlighted from our data. The prevalence of Blastocystis sp. was not significantly higher in patients with digestive symptoms or diagnosed with chronic bowel diseases. Among symptomatic patients, Blastocystis sp. infection was significantly associated with abdominal pain. Gender, socioeconomic status, and immune status were not identified as potential risk factors associated with infection. Among a total of 141 subtyped isolates, subtype 3 was predominant (43.3 %), followed by subtype 1 and subtype 4 (20 %), subtype 2 (12.8 %), subtype 6 and subtype 7 (2.1 %). No association between ST and clinical symptoms was statistically evidenced.
  
  
  CONCLUSIONS
  A high prevalence of Blastocystis sp. infection was found in our French patient population. Seasonal impact on the prevalence of Blastocystis sp. was highlighted and recent travels and age were identified as main risk factors for infection. Most cases were caused by subtypes 1 to 4, with a predominance of subtype 3. Large variations in both prevalence and ST distribution between hospitals were also observed, suggesting distinct reservoirs and transmission sources of the parasite.
authors: Université de Lille, CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, U1019 - UMR 8204 - CIIL - Centre d'Infection et d'Immunité de Lille, 1 rue du Professeur Calmette, BP 245, 59019, Lille cedex, France.
authors: Dima
authors: D
authors: El Safadi
authors: Université de Lille, CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, U1019 - UMR 8204 - CIIL - Centre d'Infection et d'Immunité de Lille, 1 rue du Professeur Calmette, BP 245, 59019, Lille cedex, France.
authors: Amandine
authors: A
authors: Cian
authors: Laboratoire de Parasitologie-Mycologie, CHU Gabriel-Montpied, Clermont-Ferrand, France.|Clermont Université, Université Blaise Pascal-Université d'Auvergne - CNRS UMR 6023 Laboratoire Microorganismes: Génome et Environnement, Clermont-Ferrand, France.
authors: Céline
authors: C
authors: Nourrisson
authors: CHU Clermont-Ferrand, Unité de Biostatistiques, Direction de la Recherche Clinique (DRCI), Clermont-Ferrand, France.
authors: Bruno
authors: B
authors: Pereira
authors: Laboratoire de Parasitologie-Mycologie, CHU de Montpellier, CNRS UMR 5290/IRD 224/UM1, Université de Montpellier 1, Montpellier, France.
authors: Christelle
authors: C
authors: Morelle
authors: Laboratoire de Parasitologie-Mycologie, CHU de Montpellier, CNRS UMR 5290/IRD 224/UM1, Université de Montpellier 1, Montpellier, France.
authors: Patrick
authors: P
authors: Bastien
authors: Laboratoire de Parasitologie-Mycologie, CHU de Besançon, Besançon, France.
authors: Anne-Pauline
authors: AP
authors: Bellanger
authors: Laboratoire de Parasitologie-Mycologie, AP-HP Hôpital Henri Mondor, Créteil, France.
authors: Françoise
authors: F
authors: Botterel
authors: Institut de Parasitologie et de Pathologie Tropicale de Strasbourg, Université de Strasbourg, Hôpitaux Universitaires de Strasbourg, Strasbourg, France.
authors: Ermanno
authors: E
authors: Candolfi
authors: Service de Parasitologie-Mycologie-Médecine Tropicale, CHU de Tours/CEPR Inserm U1100 Equipe 3, Université François-Rabelais de Tours, Tours, France.
authors: Guillaume
authors: G
authors: Desoubeaux
authors: Département de Parasitologie-Mycologie, Faculté de Médecine de Montpellier-Nîmes, Université de Montpellier I, CHU de Montpellier, Montpellier, France.
authors: Laurence
authors: L
authors: Lachaud
authors: Département de Parasitologie et Mycologie Médicale, Laboratoire de Parasitologie-Mycologie, Institut de Biologie, CHU de Nantes, EA1155-IICiMed, Université de Nantes, Nantes, France.
authors: Florent
authors: F
authors: Morio
authors: Laboratoire de Parasitologie-Mycologie CHU de Nice, C3M INSERM U1065, Université de Nice Sophia Antipolis, Nice, France.
authors: Christelle
authors: C
authors: Pomares
authors: Service de Parasitologie, Hospices Civils de Lyon, Lyon, France.
authors: Meja
authors: M
authors: Rabodonirina
authors: Clermont Université, Université Blaise Pascal-Université d'Auvergne - CNRS UMR 6023 Laboratoire Microorganismes: Génome et Environnement, Clermont-Ferrand, France.
authors: Ivan
authors: I
authors: Wawrzyniak
authors: Clermont Université, Université Blaise Pascal-Université d'Auvergne - CNRS UMR 6023 Laboratoire Microorganismes: Génome et Environnement, Clermont-Ferrand, France.
authors: Frédéric
authors: F
authors: Delbac
authors: Université de Lille, CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, U1019 - UMR 8204 - CIIL - Centre d'Infection et d'Immunité de Lille, 1 rue du Professeur Calmette, BP 245, 59019, Lille cedex, France.
authors: Nausicaa
authors: N
authors: Gantois
authors: Université de Lille, CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, U1019 - UMR 8204 - CIIL - Centre d'Infection et d'Immunité de Lille, 1 rue du Professeur Calmette, BP 245, 59019, Lille cedex, France.
authors: Gabriela
authors: G
authors: Certad
authors: Université de Lille, CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, U1019 - UMR 8204 - CIIL - Centre d'Infection et d'Immunité de Lille, 1 rue du Professeur Calmette, BP 245, 59019, Lille cedex, France.|Département de Parasitologie-Mycologie, CHU de Lille, Faculté de Médecine, Lille, France.
authors: Laurence
authors: L
authors: Delhaes
authors: Laboratoire de Parasitologie-Mycologie, CHU Gabriel-Montpied, Clermont-Ferrand, France. ppoirier@chu-clermontferrand.fr.|Clermont Université, Université Blaise Pascal-Université d'Auvergne - CNRS UMR 6023 Laboratoire Microorganismes: Génome et Environnement, Clermont-Ferrand, France. ppoirier@chu-clermontferrand.fr.
authors: Philippe
authors: P
authors: Poirier
authors: Université de Lille, CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, U1019 - UMR 8204 - CIIL - Centre d'Infection et d'Immunité de Lille, 1 rue du Professeur Calmette, BP 245, 59019, Lille cedex, France. eric.viscogliosi@pasteur-lille.fr.
authors: Eric
authors: E
authors: Viscogliosi
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D016844:Blastocystis / Q000145:classification / Q000302:isolation & purification; D016776:Blastocystis Infections / Q000175:diagnosis / Q000453:epidemiology*; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D005243:Feces / Q000469:parasitology; D005260:Female; D005602:France; D006801:Humans; D007223:Infant; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D012307:Risk Factors; D055815:Young Adult
keywords: Blastocystis sp; Intestinal parasite; Molecular epidemiology; PCR; Risk factors for infection; Subtyping