Diagnosis of Coxiella burnetii Cattle Abortion: A One-Year Observational Study

Abstract

Q fever is a zoonosis occurring worldwide in livestock. Often neglected in differential diagnoses, Q fever can persist in herds causing financial losses. In ruminants, well-known manifestations of Q fever are metritis, infertility, abortion, stillbirth and delivery of a weak or premature calf. In cattle, Q fever is frequently asymptomatic and/or under-reported. Few studies are available on the diagnosis of Coxiella burnetii as a cause of abortion in cattle using polymerase chain reaction (PCR) for pathogen detection while enzyme-linked immunosorbent assay (ELISA) is used to assess exposure. Moreover, existing studies include a relatively small number of abortions. The aim of this study is to assess, in the southern part of Belgium, during a year, the performance of diagnosis of C. burnetii as a cause of abortion and the putative benefit of enhanced serology using anamnesis (animal patient data, and present, past and environmental history). A one-year random selection of 1212 abortions was analysed both with the PCR method (tissues from fetuses) and two commercialised ELISAs (sera from the mothers). Relative sensitivity and specificity of the ELISA tests were assessed using PCR as the reference test. The prevalence of C. burnetii PCR positive was 8.5% (95% CI: 6.99–10.21). The diagnostic value of the ELISA tests was assessed using the area under the receiver operating characteristic curve (AUC-ROC). The sensitivity, specificity and AUC-ROC were similar for both ELISA tests. The diagnostic capacity of the ELISA was confirmed and slightly enhanced if anamnestic information was integrated with a unique scoring index system. A high negative predictive value was demonstrated and a significant reverse association between Ct values and a percentage of the ratio of the optical density between the sample and the positive control (ELISA A or ELISA B) enabling the use of ELISA as an exclusion diagnostic. This study is original by integrating the serological result and the anamnesis in a single index. It opens a new window in enhanced veterinary clinical decision-making.

Detection of infectious agents in equine pregnancy loss, stillbirth and neonatal death

“…This prevalence suggests a high circulation of this bacterium in Belgium. Recently, 8.5% of Belgian bovine abortions originating from Wallonia, were tested positive for C. burnetii on the basis of a PCR test on a pool of fetal spleen and, if available, placental cotelydones (Saegerman et al, 2022). In Flanders, a percentage of only 1.5 % of bovine cases tested positive for C. burnetii.…”

Exposure of Dairy Cows to Coxiella burnetii in Greece: Surveillance Results and Association of Bacterial Presence with Environmental Variables

“…The type of strain involved in infected livestock is a possible factor affecting clinical outcomes [4]. In recent years, the pathogen has been considered as the etiological agent of approximately 10% of abortions reported in cattle in various studies performed in different countries, e.g., Belgium, Italy, Brazil, and others [5][6][7]. A large study performed previously [8] showed that the main shedding routes in cattle are via the milk and vaginal mucus.…”

A sero-epidemiological analysis of Coxiella burnetii infection and its risk factors in livestock from Addis Ababa, Adama, and Modjo abattoirs and pastoral areas of Oromia, Ethiopia

“…Coxiella burnetii is a bacterium that causes Q fever in humans [ 1 , 2 ] and coxiellosis in animals [ 3 , 4 ]. Transmission is primarily through inhalation of dry aerosol particles from infected animals although tick associated transmission has also been reported in animals [ 5 ].…”