A longitudinal study of serological responses to Coxiella burnetii and shedding at kidding among intensively-managed goats supports early use of vaccines

Abstract

Vaccination against Coxiella burnetii, the cause of Q fever, is reportedly the only feasible strategy of eradicating infection in ruminant herds. Preventive vaccination of seronegative goats is more effective in reducing shedding of C. burnetii than vaccinating seropositive goats. The age at which goats born on heavily-contaminated farms first seroconvert to C. burnetii has not yet been documented. In a 16-month birth cohort study, the age at which goats seroconverted against C. burnetii was investigated; 95 goats were bled every 2 weeks and tested for antibodies against C. burnetii. Risk factors for seroconversion were explored and goats shedding C. burnetii were identified by testing vaginal swabs taken at the goats’ first kidding using a com1 polymerase chain reaction assay. The first surge in the number of goats with IgM to C. burnetii was observed at week 9. Thus, a first vaccination not later than 8 weeks of age to control C. burnetii in highly contaminated environments is indicated. The odds of seroconversion were 2.0 times higher [95% confidence interval (CI) 1.2, 3.5] in kids born by does with serological evidence of recent infection (IgM seropositive) compared to kids born by IgM seronegative does, suggesting either in utero transmission or peri-parturient infection. The rate of seroconversion was 4.5 times higher (95% CI 2.1, 9.8) during than outside the kidding season, highlighting the risk posed by C. burnetii shed during kidding, even to goats outside the kidding herd. Shedding of C. burnetii at kidding was detected in 15 out of 41 goats infected before breeding.Electronic supplementary materialThe online version of this article (doi:10.1186/s13567-017-0452-3) contains supplementary material, which is available to authorized users.

Validation of an Indirect Immunofluorescence Assay and Commercial Q Fever Enzyme-Linked Immunosorbent Assay for Use in Macropods

“…In humans, phase II is associated with acute Q fever, with phase II-specific IgG antibodies appearing earlier and persisting at higher titers than phase I antibodies ( 55 ). A similar antibody response has also been demonstrated in mice and goats ( 56 , 57 ). The macropods included in this study demonstrated a larger proportion seropositive to phase I antigen, compared to phase II antigen, with no animals positive for phase II antibody only.…”

Seroprevalence and factors associated with Toxoplasma gondii-, Neospora caninum- and Coxiella burnetii-infections in dairy goat flocks from Costa Rica

“…Finally, no clinical signs related to toxoplasmosis, neosporosis or Q fever were detected in any analyzed flocks, which can be related to several variables, such as stage of infection, pathogen strains, seroconversion and the animal immunity, as previously reported in the literature (Bezerra et al, 2013;Porto et al, 2016;Muleme et al, 2017). The absence of clinical reproductive signs (e. g. abortions and infertility) and their relationship with these mentioned variables (particularly with seroconversion) suggests also the presence of persistent or latent infected goats in these flocks, but their confirmation using immunoblot techniques are necessary to assess this hypothesis.…”

Experimental Coxiella burnetii infection in non-pregnant goats and the effect of breeding

“…In this way nonpregnant goats that are infected with C. burnetii before breeding, could play a role in the dynamics of Q fever in a goat herd although the exact attribution of pre-bred infected goats cannot be derived from this study. This risk can be further reduced by vaccinating the kids as early as possible, which Muleme et al have already suggested as an approach for eradicating Q fever from an infected herd [22].…”