Progression of Coxiella burnetii infection after implementing a two-year vaccination program in a naturally infected dairy cattle herd

Abstract

BackgroundThe high prevalence of Coxiella burnetii infection in dairy cattle herds recently reported and the long survival time of the bacterium in the environment pose a risk to human and animal health that calls for the implementation of control measures at herd level. This study presents the results of a 2-year vaccination program with an inactivated phase I vaccine in a Spanish dairy herd naturally infected with C. burnetii. Calves older than 3 months and non-pregnant heifers and cows were vaccinated in April 2011 and the farm was subsequently visited at a monthly basis for vaccination of recently calved cows and calves that reached the age of 3 months. Annual booster doses were given to previous vaccinated animals as well. The effectiveness of the vaccine was assessed in terms of level of C. burnetii shedding through milk and uterine fluids and environmental contamination as determined by polymerase chain reaction (PCR).ResultsThe percentage of shedder animals through uterine fluids and milk progressively decreased, and C. burnetii DNA load in bulk-tank milk samples was low at the end of the study. The average seroconversion rate in not yet vaccinated animals, which acted as control group, was 8.6% during the first year and 0% in the second year. DNA of C. burnetii was found in aerosols and dust samples taken in the calving area only at the beginning of the study, whereas slurry samples remained C. burnetii PCR positive for at least 18 months. Multiple Locus Variable number tandem-repeat Analysis identified the same genotype in all C. burnetii DNA positive samples.ConclusionsIn the absence of any changes in biosecurity, the overall reduction of C. burnetii infection in animals to 1.2% milk shedders and the reduced environment contamination found at the end of the study was ascribed to the effects of vaccination together with the culling of milk shedders. Vaccination has to be planned as a medium-long term strategy to suppress risks of re-infection.

Genetic diversity and variation over time of Coxiella burnetii genotypes in dairy cattle and the farm environment

“…Often persistent genotypes were among the three most prevalent types (I, J or AB), which is in agreement with results from other studies carried out in dairy cattle herds (Piñero et al, 2014a) and sheep flocks (Astobiza et al, 2012b). In those cases when different genotypes were found between samplings (32% of the herds), types generally differed in only one marker.…”

Erfahrungen von Tierhaltern in niedersächsischen Milchkuhbetrieben mit der Impfung gegen Q-Fieber

“…So wurden ein Rückgang von Aborten (3) sowie eine um den Faktor 1,22 verbesserte Trächtigkeitsrate (18) nach der Impfung festgestellt. Generell wurde nachgewiesen, dass sich die Ausscheidung von Coxiella burnetii, insbesondere über Uterusflüssigkeiten und Milch, nach der Impfung beständig reduzierte (22).…”

“…Ein Tierhalter will nicht weiter impfen, sondern zukünftig alle Tiere testen und sie im Falle eines positiven Befundes aus dem Bestand entfernen. Auch in der Literatur wird empfohlen, Tiere, die den Erreger dauerhaft mit der Milch ausscheiden aus den Beständen zu entfernen, allerdings immer in Kombination mit einer mittel-bis langfristig angelegten Bestandsimpfung (22).…”

QTest: A new way to easily sample, store, and ship samples to perform Q fever PCR analysis on bulk tank milk

“…Indeed, BTM samples are suitable for repeated sampling. Thus, RT-PCR analysis of BTM samples is frequently used in dairy herds to evaluate the presence of C. burnetii, either for initial herd screening or for monitoring the effectiveness of preventive health schemes (Guatteo et al, 2007a;Taurel et al, 2012Taurel et al, , 2014Valergakis et al, 2012;Piñero et al, 2014).…”