TY - JOUR

T1 - Dynamics of relationship between the presence of Coxiella burnetii DNA, antibodies, and intrinsic variables in cow milk and bulk tank milk from Danish dairy cattle

A1 - Angen,Øystein

A1 - Ståhl,Marie

A1 - Agerholm,J. S.

A1 - Christoffersen,Anna-Bodil

A1 - Agger,J. F.

AU - Angen,Øystein

AU - Ståhl,Marie

AU - Agerholm,J. S.

AU - Christoffersen,Anna-Bodil

AU - Agger,J. F.

PB - American Dairy Science Association

PY - 2011

Y1 - 2011

N2 - Milk samples of 12 Danish dairy herds were collected 3 times during an 11-mo period and tested for Coxiella burnetii DNA by real-time PCR, detecting the IS1111 element, and for the presence of antibodies against the bacterium by ELISA. On average, 25% of 1,514 samples were seropositive and 32% were positive for C. burnetii DNA. Among the 485 DNA-positive samples, quantification cycle values ranging from 15.8 to 37.8 were found. Test sensitivity did not increase after DNA extraction from the cream fraction compared with full milk. The relationship between antibody levels and bacterial shedding was investigated among 166 cows from 9 herds. The prevalence levels of C. burnetii DNA and antibodies in the herds were found to be rather stable for 6 of the herds. The test results were highly influenced by results obtained 3 to 7 mo earlier. A significant association between the antibody titer and the DNA shedding level at the same and the preceding visit was found. In addition, a significant association between the antibody titer and the antibody titers 3 to 11 mo earlier was found. A multivariable analysis identified a significant increase in C. burnetii DNA shedding with increasing parity and increasing protein concentration in milk. The antibody levels in bulk tank milk and prevalence levels of C. burnetii DNA and antibodies in individual cow milk samples were correlated. A significant correlation was also found between the quantification cycle values of the cow samples (weighted according to milk yield) and the C. burnetii concentration in bulk tank milk.

AB - Milk samples of 12 Danish dairy herds were collected 3 times during an 11-mo period and tested for Coxiella burnetii DNA by real-time PCR, detecting the IS1111 element, and for the presence of antibodies against the bacterium by ELISA. On average, 25% of 1,514 samples were seropositive and 32% were positive for C. burnetii DNA. Among the 485 DNA-positive samples, quantification cycle values ranging from 15.8 to 37.8 were found. Test sensitivity did not increase after DNA extraction from the cream fraction compared with full milk. The relationship between antibody levels and bacterial shedding was investigated among 166 cows from 9 herds. The prevalence levels of C. burnetii DNA and antibodies in the herds were found to be rather stable for 6 of the herds. The test results were highly influenced by results obtained 3 to 7 mo earlier. A significant association between the antibody titer and the DNA shedding level at the same and the preceding visit was found. In addition, a significant association between the antibody titer and the antibody titers 3 to 11 mo earlier was found. A multivariable analysis identified a significant increase in C. burnetii DNA shedding with increasing parity and increasing protein concentration in milk. The antibody levels in bulk tank milk and prevalence levels of C. burnetii DNA and antibodies in individual cow milk samples were correlated. A significant correlation was also found between the quantification cycle values of the cow samples (weighted according to milk yield) and the C. burnetii concentration in bulk tank milk.

U2 - 10.3168/jds.2011-4197

DO - 10.3168/jds.2011-4197

JO - Journal of Dairy Science

JF - Journal of Dairy Science

SN - 0022-0302

IS - 12

VL - 94

SP - 5750

EP - 5759

ER -