title: High frequency of chlamydial co-infections in clinically healthy sheep flocks.
abstract: BACKGROUND
  The epidemiological situation of ovine chlamydial infections in continental Europe, especially Germany is poorly characterised. Using the German state of Thuringia as a model example, the chlamydial sero- and antigen prevalence was estimated in thirty-two randomly selected sheep flocks with an average abortion rate lower than 1%. Seven vaccinated flocks were reviewed separately.
  
  
  RESULTS
  A wide range of samples from 32 flocks were examined. Assumption of a seroprevalence of 10% (CI 95%) at flock level, revealed that 94% of the tested flocks were serologically positive with ongoing infection (i.e. animals with seroconversion) in nearly half (47%) of the flocks. On the basis of an estimated 25% antigen prevalence (CI 95%), PCR and DNA microarray testing, together with sequencing revealed the presence of chlamydiae in 78% of the flocks. The species most frequently found was Chlamydophila (C.) abortus (50%) followed by C. pecorum (47%) and C. psittaci genotype A (25%). Mixed infections occurred in 25% of the tested flocks. Samples obtained from the vaccinated flocks revealed the presence of C. abortus field samples in 4/7 flocks. C. pecorum was isolated from 2/7 flocks and the presence of seroconversion was determined in 3/7 flocks.
  
  
  CONCLUSIONS
  The results imply that chlamydial infections occur frequently in German sheep flocks, even in the absence of elevated abortion rates. The fact that C. pecorum and the potentially zoonotic C. psittaci were found alongside the classical abortifacient agent C. abortus, raise questions about the significance of this reservoir for animal and human health and underline the necessity for regular monitoring. Further studies are needed to identify the possible role of C. psittaci infections in sheep.
authors.affiliation: Institut für Bakterielle Infektionen und Zoonosen, Friedrich-Loeffler-Institut, Naumburger Strasse 96a, 07743 Jena, Germany.
authors.forename: Hannah
authors.initials: H
authors.lastname: Lenzko
authors.forename: Udo
authors.initials: U
authors.lastname: Moog
authors.forename: Klaus
authors.initials: K
authors.lastname: Henning
authors.forename: Robert
authors.initials: R
authors.lastname: Lederbach
authors.forename: Roland
authors.initials: R
authors.lastname: Diller
authors.forename: Christian
authors.initials: C
authors.lastname: Menge
authors.forename: Konrad
authors.initials: K
authors.lastname: Sachse
authors.forename: Lisa D
authors.initials: LD
authors.lastname: Sprague
mesh_terms: D000818:Animals; D002689:Chlamydia; D002690:Chlamydia Infections / Q000453:epidemiology / Q000382:microbiology / Q000662:veterinary*; D002691:Chlamydophila psittaci; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary; D005260:Female; D005858:Germany / Q000453:epidemiology; D020411:Oligonucleotide Array Sequence Analysis / Q000662:veterinary; D016133:Polymerase Chain Reaction / Q000662:veterinary; D015995:Prevalence; D016036:Seroepidemiologic Studies; D012756:Sheep / Q000382:microbiology; D012757:Sheep Diseases / Q000453:epidemiology / Q000382:microbiology*