Application of fluorescent in situ hybridisation for demonstration of Coxiella burnetii in placentas from ruminant abortions.

A fluorescent in situ hybridisation (FISH) assay targeting 16S ribosomal RNA was developed for detection of the zoonotic bacterium Coxiella burnetii in formalin-fixed, paraffin-embedded tissue, and applied on placentas from ruminant abortions. The applicability of the FISH assay was compared to immunohistochemistry (IHC) using human positive control serum in 12 cases of C. burnetii-associated placentitis as well as 7 negative control tissue samples. In all 12 cases the bacterium was detected within trophoblasts as well as free in the placental debris by both FISH and IHC. Extensive and significant infection by C. burnetii was revealed in 10 of the cases, whereas a slighter and focal distribution of the bacterium was observed in two cases. 90 aborted placentas from Danish ruminants were investigated by FISH. C. burnetii was detected in one bovine case only, representing the first confirmation of C. burnetii in Danish animals. The study shows that FISH targeting 16S ribosomal RNA is a feasible diagnostic tool for detection of C. burnetii in tissue samples and fully comparable to IHC.

Veterinary and medical aspects of abortion in Danish sheep.

The Danish sheep population totals around 144,000 animals, but little is known of the causes and prevalance of diseases. This study focuses on the causes of abortion in Danish sheep. During one breeding season, aborted foetuses and stillbirths with signs of intrauterine death or malformation were submitted for laboratory examination from a population of 3,758 breeding ewes. Samples from 24 incidents of abortion and 21 ewes delivering malformed lambs or lambs with ante partum decomposition were submitted. A specific aetiology was established in 66.7% and 14.3% of the cases, respectively. Bacterial pathogens were the most prevalent cause of abortion. Several of the abortifacients were zoonotic microorganisms, for example Listeria monocytogenes, Campylobacter fetus subsp. fetus, Yersinia pseudotuberculosis and Toxoplasma gondii. The identified microorganisms probably represent the most common causes of abortion in Danish sheep but occurrence in Denmark of other pathogens such as Coxiella burnetii and Chlamydophila abortus cannot be excluded. Due to the high prevalence of zoonotic microorganisms, precautions must be taken in handling abortions or assisting lambing, especially for pregnant women.