Q fever is a widespread zoonotic disease caused by Coxiella burnetii, a ubiquitous intracellular bacterium infecting humans and a variety of animals. Transmission is primarily but not exclusively airborne, and ticks are usually thought to act as vectors. We argue that, although ticks may readily transmit C. burnetii in experimental systems, they only occasionally transmit the pathogen in the field. Furthermore, we underscore that many Coxiella-like bacteria are widespread in ticks and may have been misidentified as C. burnetii. Our recommendation is to improve the methods currently used to detect and characterize C. burnetii, and we propose that further knowledge of Coxiella-like bacteria will yield new insights into Q fever evolutionary ecology and C. burnetii virulence factors.

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Q fever is a zoonosis caused by Coxiella burnetii, a bacterium largely carried by ruminants and shed into milk, vaginal mucus, and feces. The main potential hazard to humans and animals is due to shedding of bacteria that can then persist in the environment and be aerosolized. The purpose of this study was to evaluate shedding after an outbreak of Q fever abortion in goat herds and to assess the relationship with the occurrence of abortions and antibody responses. Aborting and nonaborting goats were monitored by PCR for C. burnetii shedding 15 and 30 days after the abortion episodes. PCR analysis of all samples showed that 70% (n ‫؍‬ 50) of the aborting and 53% (n ‫؍‬ 70) of the nonaborting goats were positive. C. burnetii was shed into vaginal mucus, feces, and milk of 44%, 21%, and 38%, respectively, of goats that aborted and 27%, 20%, and 31%, respectively, of goats that delivered normally. Statistical comparison of these shedding results did not reveal any difference between these two groups. PCR results obtained for the vaginal and fecal routes were concordant in 81% of cases, whereas those for milk correlated with only 49% of cases with either vaginal or fecal shedding status. Serological analysis, using enzyme-linked immunosorbent assay (ELISA), indirect immunofluorescence assay (IFA), and complement fixation tests, showed that at least 24% of the seronegative goats shed bacteria. Positive vaginal and fecal shedding, unlike positive milk shedding, was observed more often in animals that were weakly positive or negative by ELISA or IFA. Two opposite shedding trends were thus apparent for the milk and vaginal-fecal routes. Moreover, this study showed that a nonnegligible proportion of seronegative animals that delivered normally could excrete C. burnetii.

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Coxiella burnetii is the causative agent of Q fever, a well-known zoonosis. The clinical presentation of Q fever is non-specific in most animals, with the exception of ruminants where Q fever is responsible for late abortion and stillbirths. Q fever has only recently been included in the Community Summary Reports on Zoonoses. Reporting from the European Union Member States is not harmonised and the level of information available varies considerably. Therefore, a project on the development of harmonised schemes for the monitoring and reporting of Q fever in animals in the European Union was launched. More than 30 different animal species susceptible to Q fever have been recorded in Europe. However, domestic ruminants (cattle, sheep and goats) represent the source most often associated to human outbreaks. Thus, it is proposed to focus monitoring schemes on domestic ruminants. A standardised definition is suggested for a herd/flock considered as clinically affected with Q fever. This includes the occurrence of serial abortions, confirmation of the presence of C. burnetii by Polymerase Chain Reaction and positive serology by Enzyme-Linked Immunosorbent Assay. It is further proposed that the monitoring of Q fever should mainly rely on a passive system aiming at the identification of clinically affected herds and flocks and diagnostic methods should include a combination of Enzyme-Linked Immunosorbent Assay and Polymerase Chain Reactions. Guidelines for the interpretation of the test results are presented for cattle and small ruminants. Active monitoring schemes may be applied in countries that need to evaluate Q fever prevalence in their animal populations when the disease frequency in humans or animals is suspected to be high. Active monitoring can involve either bulk tank milk testing or sero-surveys. Harmonised reporting forms are suggested for submitting the information at Community level.

This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Performances of an ELISA, an immunofluorescence assay (IFA) and a complement fixation 23 test (CFT) were assessed for detecting antibodies against Coxiella burnetii after Q fever 24 abortions in naturally infected goats. The goal of the study was to provide information useful 25 for veterinary serodiagnosis in regard to categories of goats either experiencing Q fever 26 abortion or not, blood sampling times and recommended cut-offs. The study was conducted 27 on 8 goat herds with evidence of C. burnetii abortions. In each herd, at least 5 goats that had 28 aborted and 10 goats prior to parturition or at term were monitored 15, 30 and 60 days (D15, 29 D30, D60) after the onset of Q fever abortion. The overall CFT results distribution did not 30 differ between the two groups of goats and showed poor agreement with the ELISA results. In 31 contrast, the ELISA and IFA results revealed comparable significant differences, but overall 32 the ELISA test was slightly more sensitive than the IFA test. Seroprevalence, according to 33 ELISA and IFA respectively, was higher in the aborting (88% and 82%) than in the non-34 aborting group (60% and 50%). High levels of serum antibodies were detected in goats post-35 abortion with an average of 114 %OD using ELISA and a log10(titer) of 2.4 using IFA. 36 Strongly positive ELISA (%OD>80) and positive IFA results (log 10 (titers)>1.9) were 37 significantly associated with abortion. Sampling on D15 gave the best association with ORs 38 of 10 for ELISA and 6 for IFA. The practical interest of these results is discussed. 39 40

Q fever is a worldwide zoonosis caused by Coxiella burnetii. Domestic ruminants are considered to be the main reservoir. Sheep, in particular, may frequently cause outbreaks in humans. Because within-flock circulation data are essential to implementing optimal management strategies, we performed a follow-up study of a naturally infected flock of dairy sheep. We aimed to (i) describe C. burnetii shedding dynamics by sampling vaginal mucus, feces, and milk, (ii) assess circulating strain diversity, and (iii) quantify barn environmental contamination. For 8 months, we sampled vaginal mucus and feces every 3 weeks from aborting and nonaborting ewes (n ‫؍‬ 11 and n ‫؍‬ 26, respectively); for lactating females, milk was obtained as well. We also sampled vaginal mucus from nine ewe lambs. Dust and air samples were collected every 3 and 6 weeks, respectively. All samples were screened using real-time PCR, and strongly positive samples were further analyzed using quantitative PCR. Vaginal and fecal samples with sufficient bacterial burdens were then genotyped by multiple-locus variable-number tandem-repeat analysis (MLVA) using 17 markers. C. burnetii burdens were higher in vaginal mucus and feces than in milk, and they peaked in the first 3 weeks postabortion or postpartum. Primiparous females and aborting females tended to shed C. burnetii longer and have higher bacterial burdens than nonaborting and multiparous females. Six genotype clusters were identified; they were independent of abortion status, and within-individual genotype diversity was observed. C. burnetii was also detected in air and dust samples. Further studies should determine whether the within-flock circulation dynamics observed here are generalizable.Q fever is a widespread zoonosis caused by Coxiella burnetii, a Gram-negative intracellular bacterium that has been reported in a broad range of host species. Livestock, especially small ruminants, are the main sources of human infections (1-3). In domestic ruminants, Q fever's major clinical manifestations are abortions and stillbirths, whose occurrence may translate into significant economic losses (1, 3). In humans, C. burnetii infections range from asymptomatic to severe. Acute forms of the disease may result in high fevers and severe pneumonia or hepatitis, and chronic forms are strongly debilitating and may be fatal when endocarditis develops in patients with underlying heart disease (4-6).Animals and humans become infected essentially through the inhalation of airborne particles contaminated with C. burnetii (3,7,8). Contaminated dust particles may remain infectious for long periods of time due to the capacity of the bacterium to differentiate into highly resistant spore-like forms (9, 10). Consequently, knowledge of C. burnetii's sources and shedding dynamics is essential to assessing the risks of disease transmission and pathogen persistence. On livestock farms, C. burnetii DNA has been found in various environmental matrices, such as dust (11-13) and aerosols (14-16). However, studies that examin...

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