title: Insights into the dynamics of endemic Coxiella burnetii infection in cattle by application of phase-specific ELISAs in an infected dairy herd.
abstract: Serological diagnosis of acute and chronic Q fever in humans relies on detection of antibodies to phase I (PhI) and II (PhII) antigens of Coxiella (C.) burnetii. Although phase-specific antigens are available, they are not yet used in ruminants as they are in humans. This study focuses on phase-specific serology as a tool for analysis of the dynamics of infection in cattle. As a prerequisite, sero-prevalence in Bavarian cattle (1) and sero-prevalences for age-groups (2) were determined by ELISA (CHEKIT Q-Fever; mix of PhI/PhII-antigen). Subsequently, phase-specific antigens were coated onto ELISA plates individually and tests were simultaneously applied in an endemically infected herd with about 90 dairy cows and 250 calves/heifers in April 2005, March 2006 and retrospectively in May and October 2004. From April 2005 onward, placentas were analysed for C. burnetii by PCR (3). (1) Sero- and herd prevalences based on 21,051 sera from 603 Bavarian dairy farms collected in 2003 were 14.8% ± 0.48% and 72.3% ± 3.6%, respectively. (2) Analysis of 3965 animals from 105 farms for which age was reported revealed a base level of sero-prevalence of less than 5% in 1-2 years old animals, it increased to 15% in 2-3 years old and reached a plateau (25-30%) in cows four years and older. (3) In May 2004 and April 2005 a peak of PhI(-)/PhII(+)-prevalence in primiparous cows (2.0-3.5 years) was observed; but not in October 2004 and March 2006. The PhI(-)/PhII(+)-pattern in primiparous cows changed to negative (one-third), PhI(+)/PhII(+) (1/3) or persisted (1/3). In contrast, sero-conversion was rare in multiparous cows (>3.5 years). If the PhI(-)/PhII(+) pattern was detected, it was due to an infection in preceding years. This pattern persisted (2/3) or changed to negative (1/3); a change to PhI(+)/PhII(+) did not occur. PhI(-)/PhII(+) in heifers (1-2 years) always changed to negative. Detection of PhII-antibodies was significantly associated with PCR-positive placentas. Remarkably, 45% of sera with the PhI(-)/PhII(+) pattern were negative for the CHEKIT Q-Fever ELISA, thus this test missed an important group of infected animals.
authors.affiliation: Bavarian Animal Health Service, Senator-Gerauer-Straße 23, D-85586 Poing, Bavaria, Germany. jens.boettcher@tgd-bayern.de
authors.forename: Jens
authors.initials: J
authors.lastname: Böttcher
authors.forename: Annette
authors.initials: A
authors.lastname: Vossen
authors.forename: Britta
authors.initials: B
authors.lastname: Janowetz
authors.forename: Michaela
authors.initials: M
authors.lastname: Alex
authors.forename: Armin
authors.initials: A
authors.lastname: Gangl
authors.forename: Andreas
authors.initials: A
authors.lastname: Randt
authors.forename: Norbert
authors.initials: N
authors.lastname: Meier
mesh_terms: D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood*; D002417:Cattle / Q000382:microbiology*; D002418:Cattle Diseases / Q000453:epidemiology / Q000382:microbiology*; D016997:Coxiella burnetii / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005858:Germany / Q000453:epidemiology; D010920:Placenta / Q000382:microbiology; D016133:Polymerase Chain Reaction; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious; D015995:Prevalence; D011778:Q Fever / Q000453:epidemiology / Q000276:immunology / Q000662:veterinary*; D016036:Seroepidemiologic Studies; D013997:Time Factors
chemical_list: D000907:Antibodies, Bacterial