title: Molecular methods routinely used to detect Coxiella burnetii in ticks cross-react with Coxiella-like bacteria.
abstract: BACKGROUND
  Q fever is a widespread zoonotic disease caused by Coxiella burnetii. Ticks may act as vectors, and many epidemiological studies aim to assess C. burnetii prevalence in ticks. Because ticks may also be infected with Coxiella-like bacteria, screening tools that differentiate between C. burnetii and Coxiella-like bacteria are essential.
  
  
  METHODS
  In this study, we screened tick specimens from 10 species (Ornithodoros rostratus, O. peruvianus, O. capensis, Ixodes ricinus, Rhipicephalus annulatus, R. decoloratus, R. geigy, O. sonrai, O. occidentalis, and Amblyomma cajennense) known to harbor specific Coxiella-like bacteria, by using quantitative PCR primers usually considered to be specific for C. burnetii and targeting, respectively, the IS1111, icd, scvA, p1, and GroEL/htpB genes.
  
  
  RESULTS
  We found that some Coxiella-like bacteria, belonging to clades A and C, yield positive PCR results when screened with primers initially believed to be C. burnetii-specific.
  
  
  CONCLUSIONS
  These results suggest that PCR-based surveys that aim to detect C. burnetii in ticks by using currently available methods must be interpreted with caution if the amplified products cannot be sequenced. Future molecular methods that aim at detecting C. burnetii need to take into account the possibility that cross-reactions may exist with Coxiella-like bacteria.
authors.affiliation: INRA, UR0346 Animal Epidemiology Unit, Saint Genès Champanelle, France; elsa.jourdain@clermont.inra.fr.
authors.forename: Jourdain
authors.initials: J
authors.lastname: Elsa
authors.affiliation: Laboratoire MIVEGEC (Maladies Infectieuses et Vecteurs: Ecologie, Génétique, Evolution et Contrôle), Centre National de la Recherche Scientifique (CNRS) Unité Mixte de Recherche UMR 5290, Université Montpellier 1 - Université Montpellier 2 - Institut pour la Recherche et le Développement, Unité de Recherche UR 224, Montpellier, France.
authors.forename: Olivier
authors.initials: O
authors.lastname: Duron
authors.affiliation: INRA, UR0346 Animal Epidemiology Unit, Saint Genès Champanelle, France.
authors.forename: Barry
authors.initials: B
authors.lastname: Séverine
authors.affiliation: Veterinary School, University of Concepción, Chillán, Chile.
authors.forename: Daniel
authors.initials: D
authors.lastname: González-Acuña
authors.affiliation: Anses, Sophia-Antipolis Laboratory, Animal Q fever Unit, Sophia-Antipolis, France.
authors.forename: Karim
authors.initials: K
authors.lastname: Sidi-Boumedine
keywords: PCR primers; Q fever; false positive; surveillance; tick endosymbiont; tick-borne diseases