title: Peripartum dynamics of Coxiella burnetii infections in intensively managed dairy goats associated with a Q fever outbreak in Australia.
abstract: Coxiella burnetii may cause reproduction disorders in pregnant animals but subclinical infection in other animals. Unrecognised disease may delay implementation of control interventions, resulting in transmission of infection to other livestock and to humans. Seroreactivity to C. burnetii phase-specific antigens, is routinely used to interpret the course of human Q fever. This approach could be similarly useful in identifying new and existing infections in livestock herds to help describe risk factors or production losses associated with the infections and the implementation of disease-control interventions. This study aimed to elucidate the dynamics of C. burnetii infections using seroreactivity to phase-specific antigens and to examine the impact of infection on milk yield in goats in an endemically-infected farm that was associated with a Q fever outbreak in Australia. Seroreactivity pre- and post-partum and milk yield were studied in 164 goats (86 nulliparous and 78 parous). Post-partum, the seroprevalence of antibodies to C. burnetti increased from 4.7% to 31.4% throughout goats' first kiddings and from 47.4% to 55.1% in goats kidding for the second or greater time. Of 123 goats that were seronegative pre-partum, 26.8% seroconverted over the three-month peri-partum period, highlighting the importance of controlling infection throughout this time. The risk of seroconversion was comparable in first or later kidders, suggesting constant risk irrespective of parity. No loss in milk production associated with seroconversion to phase 2 was observed within the first nine weeks of lactation. However, seroconversion to only phase 1 was associated with extra 0.276L of milk per day (95% Confidence Interval: 0.010, 0.543; P=0.042), which warrants further investigation to ascertain whether or not the association is causal. Further studies on seroreactivity and milk production over longer periods are required, as milk production loss caused by C. burnetti may be an additional reason to control the disease in goat herds.
authors.affiliation: Asia-Pacific Centre for Animal Health, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, Australia; The Australian Rickettsial Reference Laboratory, Geelong, Australia. Electronic address: mmuleme@gmail.com.
authors.forename: Michael
authors.initials: M
authors.lastname: Muleme
authors.affiliation: The Australian Rickettsial Reference Laboratory, Geelong, Australia.
authors.forename: John
authors.initials: J
authors.lastname: Stenos
authors.affiliation: The Australian Rickettsial Reference Laboratory, Geelong, Australia.
authors.forename: Gemma
authors.initials: G
authors.lastname: Vincent
authors.affiliation: Asia-Pacific Centre for Animal Health, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, Australia.
authors.forename: Colin R
authors.initials: CR
authors.lastname: Wilks
authors.affiliation: Asia-Pacific Centre for Animal Health, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, Australia.
authors.forename: Joanne M
authors.initials: JM
authors.lastname: Devlin
authors.affiliation: The Mackinnon Project, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Werribee, Australia.
authors.forename: Angus
authors.initials: A
authors.lastname: Campbell
authors.affiliation: Department of Agriculture and Food Systems, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, Australia.
authors.forename: Alexander
authors.initials: A
authors.lastname: Cameron
authors.affiliation: Asia-Pacific Centre for Animal Health, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, Australia.
authors.forename: Mark A
authors.initials: MA
authors.lastname: Stevenson
authors.affiliation: The Australian Rickettsial Reference Laboratory, Geelong, Australia.
authors.forename: Stephen
authors.initials: S
authors.lastname: Graves
authors.affiliation: Asia-Pacific Centre for Animal Health, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, Australia.
authors.forename: Simon M
authors.initials: SM
authors.lastname: Firestone
mesh_terms: D000818:Animals; D000907:Antibodies, Bacterial; D001315:Australia / Q000453:epidemiology; D016997:Coxiella burnetii / Q000276:immunology / Q000302:isolation & purification*; D003612:Dairying; D004196:Disease Outbreaks / Q000662:veterinary; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary; D005260:Female; D015511:Goat Diseases / Q000097:blood / Q000453:epidemiology* / Q000382:microbiology*; D006041:Goats; D007074:Immunoglobulin G; D007774:Lactation; D016014:Linear Models; D008892:Milk / Q000382:microbiology*; D011247:Pregnancy; D011778:Q Fever / Q000097:blood / Q000453:epidemiology / Q000662:veterinary*; D016036:Seroepidemiologic Studies; D012756:Sheep
chemical_list: D000907:Antibodies, Bacterial; D007074:Immunoglobulin G
keywords: Control; Coxiella burnetii; Goats; Production losses; Transmission