title: Co-infection of Ticks: The Rule Rather Than the Exception.
abstract: BACKGROUND
  Ticks are the most common arthropod vectors of both human and animal diseases in Europe, and the Ixodes ricinus tick species is able to transmit a large number of bacteria, viruses and parasites. Ticks may also be co-infected with several pathogens, with a subsequent high likelihood of co-transmission to humans or animals. However few data exist regarding co-infection prevalences, and these studies only focus on certain well-known pathogens. In addition to pathogens, ticks also carry symbionts that may play important roles in tick biology, and could interfere with pathogen maintenance and transmission. In this study we evaluated the prevalence of 38 pathogens and four symbionts and their co-infection levels as well as possible interactions between pathogens, or between pathogens and symbionts.
  
  
  RESULTS
  A total of 267 Ixodes ricinus female specimens were collected in the French Ardennes and analyzed by high-throughput real-time PCR for the presence of 37 pathogens (bacteria and parasites), by rRT-PCR to detect the presence of Tick-Borne encephalitis virus (TBEV) and by nested PCR to detect four symbionts. Possible multipartite interactions between pathogens, or between pathogens and symbionts were statistically evaluated. Among the infected ticks, 45% were co-infected, and carried up to five different pathogens. When adding symbiont prevalences, all ticks were infected by at least one microorganism, and up to eight microorganisms were identified in the same tick. When considering possible interactions between pathogens, the results suggested a strong association between Borrelia garinii and B. afzelii, whereas there were no significant interactions between symbionts and pathogens.
  
  
  CONCLUSIONS
  Our study reveals high pathogen co-infection rates in ticks, raising questions about possible co-transmission of these agents to humans or animals, and their consequences to human and animal health. We also demonstrated high prevalence rates of symbionts co-existing with pathogens, opening new avenues of enquiry regarding their effects on pathogen transmission and vector competence.
authors.affiliation: UMR Bipar, Anses, INRA, ENVA 14 Rue Pierre et Marie Curie, Maisons-Alfort, France.
authors.forename: Sara
authors.initials: S
authors.lastname: Moutailler
authors.affiliation: Université de Lyon, Lyon, France; Université Lyon 1, Villeurbanne, France; CNRS, UMR5557, Ecologie Microbienne, Villeurbanne, France; INRA, UMR1418, Villeurbanne, France.
authors.forename: Claire
authors.initials: C
authors.lastname: Valiente Moro
authors.affiliation: EPIA, INRA, 63122 Saint Genès Champanelle, France.
authors.forename: Elise
authors.initials: E
authors.lastname: Vaumourin
authors.affiliation: UMR Bipar, Anses, INRA, ENVA 14 Rue Pierre et Marie Curie, Maisons-Alfort, France.
authors.forename: Lorraine
authors.initials: L
authors.lastname: Michelet
authors.affiliation: Université de Lyon, Lyon, France; Université Lyon 1, Villeurbanne, France; CNRS, UMR5557, Ecologie Microbienne, Villeurbanne, France; INRA, UMR1418, Villeurbanne, France.
authors.forename: Florence Hélène
authors.initials: FH
authors.lastname: Tran
authors.affiliation: UMR Bipar, Anses, INRA, ENVA 14 Rue Pierre et Marie Curie, Maisons-Alfort, France.
authors.forename: Elodie
authors.initials: E
authors.lastname: Devillers
authors.affiliation: UMR Bipar, Anses, INRA, ENVA 14 Rue Pierre et Marie Curie, Maisons-Alfort, France.|CBGP, INRA, Vetagrosup, IRD F-34988 Montferrier-sur-Lez, France.
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Cosson
authors.affiliation: EPIA, INRA, 63122 Saint Genès Champanelle, France.
authors.forename: Patrick
authors.initials: P
authors.lastname: Gasqui
authors.affiliation: Université de Lyon, Lyon, France; Université Lyon 1, Villeurbanne, France; CNRS, UMR5557, Ecologie Microbienne, Villeurbanne, France; INRA, UMR1418, Villeurbanne, France.
authors.forename: Van Tran
authors.initials: VT
authors.lastname: Van
authors.affiliation: Université de Lyon, Lyon, France; Université Lyon 1, Villeurbanne, France; CNRS, UMR5557, Ecologie Microbienne, Villeurbanne, France; INRA, UMR1418, Villeurbanne, France.|Université de La Réunion, UMR PIMIT, INSERM 1187, CNRS 9192, IRD 249, Plateforme de Recherche CYROI, Saint-Denis, La Réunion, France.
authors.forename: Patrick
authors.initials: P
authors.lastname: Mavingui
authors.affiliation: EPIA, INRA, 63122 Saint Genès Champanelle, France.
authors.forename: Gwenaël
authors.initials: G
authors.lastname: Vourc'h
authors.affiliation: UMR Bipar, Anses, INRA, ENVA 14 Rue Pierre et Marie Curie, Maisons-Alfort, France.
authors.forename: Muriel
authors.initials: M
authors.lastname: Vayssier-Taussat
mesh_terms: D063147:Animal Distribution; D000818:Animals; D001403:Babesia / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D001419:Bacteria / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D060085:Coinfection; D004269:DNA, Bacterial / Q000235:genetics; D016054:DNA, Protozoan / Q000235:genetics; D005260:Female; D005602:France; D018884:Ixodes / Q000382:microbiology* / Q000469:parasitology*; D012329:RNA, Bacterial / Q000235:genetics; D016053:RNA, Protozoan / Q000235:genetics; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D016794:Theileria / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*
chemical_list: D004269:DNA, Bacterial; D016054:DNA, Protozoan; D012329:RNA, Bacterial; D016053:RNA, Protozoan; D012336:RNA, Ribosomal, 16S