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Hou KW, Wiethoelter AK, Stevenson MA, Soares Magalhaes RJ, Lignereux L, Caraguel C, Stenos J, Vincent G, Aleri JW, Firestone SM. A cross-sectional survey of risk factors for the presence of Coxiella burnetii in Australian commercial dairy goat farms. Aust Vet J 2022; 100:296-305. [PMID: 35582949 PMCID: PMC9543512 DOI: 10.1111/avj.13163] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Revised: 02/22/2022] [Accepted: 04/03/2022] [Indexed: 11/30/2022]
Abstract
The largest Australian farm‐based outbreak of Q fever originated from a dairy goat herd. We surveyed commercial dairy goat farms across Australia by testing bulk tank milk (BTM) samples using a commercial indirect enzyme‐linked immunosorbent assay and two quantitative polymerase chain reactions (PCRs). Of the 66 commercial dairy goat herds on record, managers from 61 herds were contacted and 49 provided BTM samples. Five of the surveyed herds were positive on at least one of the diagnostic tests, thus herd‐level apparent prevalence was 10% (95% confidence interval [CI] 4 to 22). True prevalence was estimated to be 3% (95% credible interval: 0 to 18). Herd managers completed a questionnaire on herd management, biosecurity and hygiene practices and risk factors were investigated using multivariable logistic regression. Herds with >900 milking does (the upper quartile) were more likely to be Coxiella burnetii positive (odds ratio = 6.75; 95% CI 1.65 to 27.7) compared with farms with ≤900 milking does. The odds of BTM positivity increased by a factor of 2.53 (95% CI 1.51 to 4.22) for each order of magnitude increase in the number of goats per acre. C. burnetii was not detected in samples from the majority of the Australian dairy goat herds suggesting there is an opportunity to protect the industry and contain this disease with strengthened biosecurity practices. Intensification appeared associated with an increased risk of positivity. Further investigation is required to discriminate the practices associated with an increased risk of introduction to disease‐free herds, from practices associated with maintenance of C. burnetii infection in infected dairy goat herds.
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Affiliation(s)
- K W Hou
- Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, Victoria, 3010, Australia
| | - A K Wiethoelter
- Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, Victoria, 3010, Australia
| | - M A Stevenson
- Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, Victoria, 3010, Australia
| | - R J Soares Magalhaes
- UQ Spatial Epidemiology Laboratory, School of Veterinary Science, The University of Queensland, Gatton, Queensland, 4343, Australia
| | - L Lignereux
- School of Animal & Veterinary Sciences, Roseworthy Campus, The University of Adelaide, Roseworthy, South Australia, 5371, Australia
| | - C Caraguel
- School of Animal & Veterinary Sciences, Roseworthy Campus, The University of Adelaide, Roseworthy, South Australia, 5371, Australia
| | - J Stenos
- Australian Rickettsial Reference Laboratory, Barwon Health, Geelong, Victoria, 3220, Australia
| | - G Vincent
- Australian Rickettsial Reference Laboratory, Barwon Health, Geelong, Victoria, 3220, Australia
| | - J W Aleri
- School of Veterinary Medicine, College of Science, Health, Engineering and Education, Murdoch University, 90 South Street, Murdoch, Western Australia, 6150, Australia.,Centre for Animal Production and Health, Future Foods Institute, Murdoch University, 90 South Street, Murdoch, Western Australia, 6150, Australia
| | - S M Firestone
- Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, Victoria, 3010, Australia
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