Prevalence of Coxiella burnetii antibodies in Danish dairy herds

Abstract

During recent years in Denmark higher rates of antibodies to Coxiella burnetii have been detected in animals and humans than previously reported. A study based on bulk tank milk samples from 100 randomly selected dairy herds was performed to estimate the prevalence and geographical distribution of antibody positive dairy herds. Using the CHEKIT Q-Fever Antibody ELISA Test Kit (IDEXX), the study demonstrated a prevalence of 59% antibody positive herds, 11% antibody intermediate herds and 30% antibody negative herds based on the instructions provided by the manufacturer. The geographical distribution does not indicate a relationship between the regional density of dairy farms and the prevalence of antibody positive dairy farms. The result supports the hypothesis of an increase in the prevalence of positive dairy herds compared to previous years.

Figure 1

Array of antibody S/P values to Coxiella burnetii in bulk tank milk samples from 100 randomly selected Danish dairy herds in the spring of 2008.

Figure 2

Geographical distribution of 100 randomly selected Danish dairy herds tested for antibodies against Coxiella burnetii in the spring of 2008. The herds were categorized as either test positive (S/P > 40%) (Blue colour), test intermediate (30% ≤ S/P ≥ 40%) (Turquoise colour) or test negative (S/P < 30%) (White colour). The regional dairy herd density is presented by the following colours: Green: <0.07; Pale green: 0.07-0.10; Yellow: 0.10-0.14; Orange: 0.14-0.16; Red: 0.16-0.23; Purple: >0.23 herds/km².