title: The impact of Q fever-phase-specific milk serology for the diagnosis of puerperal and chronic milk shedding of C. burnetii in dairy cows.
abstract: C. burnetii infection might be associated with puerperal shedding; additionally, the chronic shedding of this pathogen in milk has been observed in individual animals. A longitudinal survey was performed in an endemically infected dairy cow herd with 100 cows in order to compare phase-specific milk-serology with pathogen shedding. From March 2010 through December 2011, 870 individual milk samples from 212 cows were analysed using both quantitative (q) PCR and phase-specific antibody-ELISA. The mean milk-shedding/cow was calculated for 137 cows with > or = 3 milk samples per cow. In addition, 110 puerperal swabs were collected after August 2010. The cows yielding three successive qPCR-positive milk samples or > 3 qPCR-positive milk samples, irrespective of the sequence of positive/negative results, were classified as chronic shedders (CS). Milk shedding was observed during the entire study, but a major period of puerperal shedding occurred from February through October 2011; 35/52 swabs tested positive, whereas only 3/58 swabs collected outside this period were positive. The PhI/PhII(+)-pattern in primiparous cows (< 36 months old) was consistent with puerperal shedding in the herd, but not at the individual level. This pattern was observed in older cows, irrespective of the period of puerperal shedding. Four primiparous CS-cows showed low-level mean shedding < 100 C.b./ml milk, and the PhI-titre increased from negative or weakly positive to more than 500 at the end of the first lactation. Puerperal shedding during the second parturition was observed in three of these cows. Six multiparous CS-cows with mean shedding exceeding 100 C.b./ml milk were characterised with stable PhI-titres of > or = 500. The three available puerperal swabs tested negative. Only one multiparous CS-cow showed low-level shedding and a PhI-titre below 500 for the entire study. In conclusion, the PhI-/PhII(+)-pattern in primiparous cows indicated puerperal shedding at the herd level, and a PhI-titre > or = 500 is a suitable screening method for the detection of chronic shedding in milk.
authors.affiliation: Bavarian Animal Health Service, Poing, Germany. jens.boettcher@tgd-bayern.de
authors.forename: Jens
authors.initials: J
authors.lastname: Böttcher
authors.forename: Dimitrios
authors.initials: D
authors.lastname: Frangoulidis
authors.forename: Magdalena
authors.initials: M
authors.lastname: Schumacher
authors.forename: Britta
authors.initials: B
authors.lastname: Janowetz
authors.forename: Armin
authors.initials: A
authors.lastname: Gangl
authors.forename: Michaela
authors.initials: M
authors.lastname: Alex
mesh_terms: D000818:Animals; D057138:Bacterial Shedding; D002417:Cattle; D002418:Cattle Diseases / Q000175:diagnosis / Q000382:microbiology*; D002908:Chronic Disease; D016997:Coxiella burnetii / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification*; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary; D005260:Female; D008137:Longitudinal Studies; D008892:Milk / Q000382:microbiology*; D011645:Puerperal Infection / Q000175:diagnosis / Q000382:microbiology / Q000662:veterinary*; D011778:Q Fever / Q000175:diagnosis / Q000382:microbiology / Q000662:veterinary*; D060888:Real-Time Polymerase Chain Reaction / Q000662:veterinary