Prevalence and factors associated with a higher or lower risk of exposure to Coxiella burnetii, Chlamydia abortus and Toxoplasma gondii in dairy cows that have aborted in Algeria

In Algeria, the prevalence of causes of abortion on dairy cattle farms (whether infectious causes or not) has been little studied. The current study involved a serological analysis conducted between October 2014 and June 2016 in northern Algeria using an enzyme-linked immunosorbent assay test on blood samples taken from 368 cows that had aborted on 124 farms. It was complemented by a survey to identify the factors associated with a higher or lower risk of exposure to Coxiella burnetii, Chlamydia abortus and Toxoplasma gondii, using univariate logistic regression and then multivariate logistic regression. The individual serological prevalences obtained were 8.4% (31/368) for C. burnetii and 12.2% (45/368) for C. abortus. For T. gondii, the individual seroprevalence was 13.8% (51/368); the factors associated with a higher risk of individual exposure were the fourth month of gestation (odds ratio [OR] = 22.68; 95% confidence interval [CI]: 1.38-392.97) and the fifth month of gestation (OR = 25.51; 95% CI: 1.47-442.11). All the other factors identified by the multivariate logistic regression were associated with a lower risk of exposure. They are the inspection visits in 2015 (OR = 0.0006; 95% CI: 0.000004-0.12) and in 2016 (OR = 0.0005; 95% CI: 0.000002-0.13) and artificial insemination (OR = 0.15; 95% CI: 0.05-0.44) for C. burnetii; winter (OR = 0.39; 95% CI: 0.15-1.00), spring (OR = 0.45; 95% CI: 0.20-0.97), and artificial insemination (OR = 0.27; 95% CI: 0.13-0.56) for C. abortus, and the number of gestations (OR = 0.38; 95% CI: 0.16-0.92) for T, gondii. The seroprevalence at herd level was 16.1% (20/124) for C. burnetii and 29.8% (37/124) for both C. abortus and T. gondii. At herd level, the risk factors associated with a higher risk of exposure to C. abortus and T. gondii were the practice of deworming (OR = 3.89; 95% CI: 1.53-9.89) and drilling individual wells as a source of drinking water (OR = 7.50; 95% CI: 2.11-26.69). For C. burnetii, the inspection visit in 2015 (OR = 0.02; 95% CI: 0.0008-0.65) and in 2016 (OR = 0.01; 95% CI: 0.0003-0.36), artificial insemination (OR = 0.21; 95% CI: 0.06-0.69) and rodent eradication (OR = 0.19; 95% CI: 0.06-0.57) were factors that reduced the risk of exposure.