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Brucella suis infection of dogs is an emerging issue worldwide requiring specific management to address zoonotic risks and animal welfare concerns. Diagnosis in dogs is routinely based on serological testing, but to date these tests have only been validated for use in production animal species and humans. This study aimed to assess the diagnostic performance of three commonly used serological tests in dogs. Canine sera (n = 989) were tested with the Rose Bengal rapid plate agglutination test (RBRPT), the complement fixation test (CFT) and a competitive ELISA (C-ELISA). Diagnostic test performance was evaluated using a three test, two population Bayesian latent class analysis accounting for conditional dependence between the three tests. Positive and negative predictive values (PPV, NPV) were calculated for a range of expected prevalence estimates for the individual tests and test combinations interpreted in series and parallel. The RBRPT showed the highest individual Se of 0.902 (95 % posterior credible interval [PCI] 0.759-0.978) and the CFT the highest individual diagnostic specificity (Sp) of 0.914 (95 % PCI 0.886-0.946). The C-ELISA had marginally the best overall diagnostic performance (Youden's index = 0.807). The CFT and the C-ELISA interpreted in parallel returned the highest combined Se and Sp (0.988 and 0.885, respectively). All tests returned NPVs of > 0.982 in 2-8 % prevalence settings. Series interpretation of the three-test combination as well as the two-test combinations of the RBRPT and the C-ELISA and the CFT and the C-ELISA produced a PPV of 0.502 when the estimated prevalence was 8 %. While all tests are suitable for the detection of B. suis antibodies in dogs, they should not be interpreted in isolation as their diagnostic value is dependent on the pre-test probability of the disease. As such they are useful tools for the diagnosis of B. suis in dogs when exposure, history and clinical presentation indicate a risk of brucellosis., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Background: Brucellosis in dogs caused by Brucella suis is an emerging zoonotic disease., Objectives: To document clinical characteristics, serology, microbiology, and clinical response to treatment in B. suis-seropositive dogs., Animals: Longitudinal study of 27 privately-owned dogs. Dogs that tested positive by serology, culture, or real-time polymerase chain reaction (qPCR) were included in the study., Methods: Clinical (physical examination and imaging) and laboratory (serology, hematology, serum biochemistry, and qPCR or culture) assessments were made at baseline and after approximately 3, 6, 12, and 18 months., Results: Dogs were followed for 10 895 dog days, with 17/27 dogs completing the 18-month follow-up. Ten dogs had signs consistent with brucellosis before enrollment (n = 4), at baseline (n = 2) or during follow-up (n = 6), with 2 dogs experiencing relapse of historical signs. Antibody titers persisted for the duration of follow-up in 15/17 dogs (88%). Radiographic (n = 5) and ultrasound (n = 11) findings, of variable clinical relevance, were observed. Brucella DNA and organisms were detected in 3 dogs, all of which had clinical signs, including in the milk of a bitch around the time of whelping. Brucella DNA was not detected in blood (n = 92 samples), urine (n = 80), saliva (n = 95) or preputial swabs (n = 78) at any time during follow-up. Six dogs underwent treatment, all of which achieved clinical remission although remission was not reflected by decreasing antibody titers., Conclusions and Clinical Importance: Most dogs with B. suis infections have subclinical infections. Serology is poorly associated with clinical disease. Excretion of organisms appears rare except in whelping bitches. Clinical management using antibiotics with or without surgery is recommended., (© 2023 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals LLC on behalf of American College of Veterinary Internal Medicine.)

Coxiella burnetii causes coxiellosis in animals and Q fever in humans, a potentially debilitating zoonotic disease commonly transmitted through domestic ruminants. To prevent transboundary spread of C. burnetii, animals may be tested prior to export. In alpacas, this process is complicated by the lack of scientific evidence for C. burnetii infection in the species, and the unique composition of camelid antibodies, which may cause false-positive results in assays developed for ruminants. We evaluated a complement fixation test (CFT; currently recommended for alpacas in New Zealand), an enzyme-linked immunosorbent assay (ELISA) and an immunofluorescence assay (IFA). Positive analytical control samples were generated through vaccination of alpacas with a human Q fever vaccine, whereas negative analytical control samples were sourced from New Zealand (deemed free of C. burnetii). Immunological assays were conducted on 131 alpaca sera submitted for export testing. Test characteristics (sensitivity, specificity, positive and negative predictive values) for CFT, ELISA and IFA were determined using Bayesian latent class analysis. Due to anticomplementary activity, 37 (28.2%) of the CFT results were inconclusive, making CFT unsuitable for routine use. Of the remaining 94 samples, 10.6%, 0% and 7.4% were positive for C. burnetii antibodies based on CFT, ELISA and IFA, respectively, yielding estimated sensitivities of 58%, 26% and 78%, and estimated specificities of 95%, 98% and 95%, with the estimates for sensitivity being imprecise, as evidenced by wide 95% credible intervals. Positive predictive values were similar across assays, albeit very low at the estimated seroprevalence of 5%. Our results indicate that, of the tests available, IFA appears to be the most appropriate for use in alpacas. Higher sensitivity of antibody detection, use of antigen detection assays and availability of samples from individuals with evidence of infection could provide additional insight into the risk of transboundary spread of C. burnetii by alpacas., (© 2021 Wiley-VCH GmbH.)

Chlamydia pecorum is a common gastrointestinal inhabitant of livestock but infections can manifest in a broad array of clinical presentations and in a range of host species. While C. pecorum is a known cause of ovine abortion, clinical cases have only recently been described in detail. Here, the prevalence and sequence types (STs) of C. pecorum in ewes from a property experiencing high levels of perinatal mortality (PNM) in New South Wales (NSW), Australia, were investigated using serological and molecular methods. Ewes that were PNM+ were statistically more likely to test seropositive compared to PNM- ewes and displayed higher antibody titres; however, an increase in chlamydial shedding from either the rectum, vagina or conjunctiva of PNM+ ewes was not observed. Multilocus sequence typing (MLST) indicated that C. pecorum ST23 was the major ST shed by ewes in the flock, was the only ST identified from the vaginal site, and was the same ST detected within aborted foetal tissues. Whole genome sequencing of C. pecorum isolated from one abortion case revealed that the C. pecorum plasmid (pCpec) contained a unique deletion in coding sequence 1 (CDS1) that was also present in C. pecorum ST23 shed from the ewes. A further unique deletion was noted in a polymorphic membrane protein gene (pmpG) of the C. pecorum chromosome, which warrants further investigation given the role of PmpG in host cell adherence and tissue tropism.This study describes novel infection parameters in a sheep flock experiencing C. pecorum -associated perinatal mortality, provides the first genomic data from an abortigenic C. pecorum strain, and raises questions about possible links between unique genetic features of this strain and C. pecorum abortion.

Results from laboratory assays for detection of animal disease are often assessed for repeatability (agreement within laboratory) and reproducibility (agreement between laboratories). This work aimed to understand the strengths and limitations of available methods for describing these quantities. Five major veterinary laboratories in Australia volunteered to participate in a designed evaluation based on repeat testing of twenty bovine sera. Sampling was stratified so that ten of the sera were negative to the virus neutralisation test (VNT) for antibody to bovine herpes virus 1 (BHV-1) and the remaining ten sera were VNT positive. Each serum was divided into 50 replicates and each laboratory assayed one replicate of each serum on a weekly basis using a commercial ELISA for BHV-1. Laboratories were blinded to the identity of sera. The data on sample to positive control ratio (S/P) for these 1000 individual assays were collated, sources of variance analysed using a random effects model, and reliability coefficients (ρ) obtained from the variance estimates as quantitative measures of within and between laboratory agreement. Coefficient of variation (CV) was calculated for combinations of sera and laboratory. CV was found to be higher for sera with the lowest mean S/P values (VNT -ve sera). For VNT -ve sera, agreement of S/P within laboratory was low to moderate (ρ: 0.01-0.27) and the agreement between all labs was low (ρ=0.02). Reliability coefficients for VNT +ve sera were very high for agreement within laboratories (ρ: 0.63-0.92) and moderate for agreement between laboratories (ρ=0.52). As well, simulation demonstrated that sero-prevalence has a dramatic affect on the reliability coefficient if sampling were to be irrespective of VNT status. We conclude that there are some limitations with the available approaches for assessing agreement within and between laboratories. Although reliability coefficients have some drawbacks they are an attractive way of reducing reliance on subjective assessment of agreement., (Crown Copyright © 2011. Published by Elsevier B.V. All rights reserved.)