A sporadic case of acute Q fever and identification of the animal source of the infection

Cultivation-free sample preparation and DNA purification for direct real-time qPCR of intracellular or spore-like Coxiella burnetii in beef, goat, and lamb meat

Coxiella burnetii is a zoonotic pathogen that has been associated with foodborne outbreaks in products with ruminant origins. However, a method to detect C. burnetii in meat has been merely studied, and commercial kits cannot efficiently fulfill this purpose. In this study, an in-house preparation method for direct real-time qPCR of C. burnetii in beef, goat, and lamb meat was designed. In the sample preparation step (step 1), trypsin digestion and cell disruption techniques were introduced to target C. burnetii in an obligate intracellular or spore-like form. Afterward, 16 DNA purification protocols involving the following steps (steps 2-3) were assessed: the precipitation of meat proteins (step 2; using 2.5, 5.0 M NaCl or 1:1, 2:1 ethanol as the precipitant) and binding of DNA to silicon dioxide particles with chaotropic salts (step 3; using 2.5, 5.0 M NaCl or 2.5, 5.0 M guanidine thiocyanate as the salt). The protocols with superior performance in high-spiked loins (estimated 4-5 log cells/g) were verified in low-spiked (1-2 log cells/g) or Bacillus thuringiensis spore-inoculated (1-2 log CFU/g) loins, ribs, and hind legs. During the protein precipitation, 5.0 M NaCl induced significantly lower protein level as demonstrated by A280, when compared to 2.5 M NaCl or ethanol (P < 0.05). For the DNA binding step, Ct values were lowered in high-spiked goat or lamb loins (3.5-6.0▾; P < 0.05) when the concentration of NaCl was doubled or guanidine thiocyanate was introduced instead of NaCl as a chaotropic salt. Based on these results, two protocols using 5.0 M NaCl as the protein precipitant and 5.0 M NaCl (N2 + N2) or guanidine thiocyanate (N2 + G2) as the chaotropic salt were selected, which demonstrated successful detection in low-spiked (Ct values of N2 + N2, 32.9-35.6; N2 + G2, 32.3-36.4) or spore-inoculated meat (N2 + N2, 30.9-37.5; N2 + G2, 29.7-32.7). Verification in low-spiked meat showed that meat type/part significantly impacted the Ct values of N2 + G2 but not those of N2 + N2. To our knowledge, this is the first study that developed a highly accessible method for detecting C. burnetii in meat which could reveal the possibility of meat-borne Q fever in humans.

Detection of zoonotic pathogens in animals performed at the University Hospital Institute Méditerranée Infection (Marseille - France)

At the University Hospital Institute Méditerranée Infection (IHU, Marseille, France), for almost thirty years, veterinarians have been carrying out epidemiological investigations, together with doctors, on animals living near human cases of zoonoses, on the one hand, and on the other hand, transverse and longitudinal epidemiological surveillance studies on animals which are reservoirs, vectors or sentinels of potentially zoonotic infections,. This article presents the methods adopted and the results obtained from these studies. They have been the subject of 76 peer-reviewed publications relating to wild animals (37 publications) and/or domestic animals (48 publications). These studies were often carried out in the field with veterinarians from the French army's health service (39 publications). They were at the origin of the detection of some thirty zoonotic pathogens in the laboratories of the IHU (64 publications) and/or other French laboratories (18 publications). Our approach is an original embodiment of the "One Health" concept.

Comparison of Coxiella burnetii Excretion between Sheep and Goats Naturally Infected with One Cattle-Associated Genotype

The main reservoir of Coxiella (C.) burnetii are ruminants. They shed the pathogen through birth products, vaginal mucus, faeces and milk. A direct comparison of C. burnetii excretions between naturally infected sheep and goats was performed on the same farm to investigate species-specific differences. The animals were vaccinated with an inactivated C. burnetii phase I vaccine at the beginning of the study period for public health reasons. Vaginal and rectal swabs along with milk specimens were taken monthly during the lambing period and once again at the next lambing season. To estimate the environmental contamination of the animals' housings, nasal swabs from every animal were taken simultaneously. Moreover, dust samples from the windowsills and straw beddings were collected. All samples were examined by qPCR targeting the IS1111 gene and the MLVA/VNTR typing method was performed. Whole genome sequencing was applied to determine the number of IS1111 copies followed by a calculation of C. burnetii genome equivalents of each sample. The cattle-associated genotype C7 was detected containing 29 IS1111 copies. Overall, goats seem to shed more C. burnetii through vaginal mucus and in particular shed more and for longer via the rectal route than sheep. This is supported by the larger quantities of C. burnetii DNA detected in caprine nasal swabs and environmental samples compared to the ovine ones. Transmission of C. burnetii from cattle to small ruminants must also be considered.