FARMERS
When to suspect Q Fever/Coxiellosis in a small ruminant herd/flock?
Coxiella burnetii is a bacterium that affects animals and people (zoonosis), with domestic ruminants being the main source of infection for humans. In infected ewes and goats, C. burnetii has a strong affinity for the reproductive organs, and the placenta in particular. Infection mostly occurs without causing obvious clinical signs, although severe clinical signs can occur. When infection causes clinical signs (coxiellosis), they mainly consist of abortions (sometimes as an outbreak or even as abortion storm), which can persist in the herd/flock[1].
Infected animals excrete C. burnetii in vaginal secretion, birth fluids and tissues, urine and faeces, and milk. Inhalation of dust and aerosols, contaminated by infectious material, is the most natural route of infection between animals (and to humans)[2].
FARMERS
When to suspect Q Fever/Coxiellosis in a small ruminant herd/flock?
Coxiella burnetii is a bacterium that affects animals and people (zoonosis), with domestic ruminants being the main source of infection for humans. In infected ewes and goats, C. burnetii has a strong affinity for the reproductive organs, and the placenta in particular. Infection mostly occurs without causing obvious clinical signs, although severe clinical signs can occur. When infection causes clinical signs (coxiellosis), they mainly consist of abortions (sometimes as an outbreak or even as abortion storm), which can persist in the herd/flock[1].
Infected animals excrete C. burnetii in vaginal secretion, birth fluids and tissues, urine and faeces, and milk. Inhalation of dust and aerosols, contaminated by infectious material, is the most natural route of infection between animals (and to humans)[2].
PURPOSE OF THIS FACTSHEET
To present the clinical signs that may be associated with the infection of sheep or goats with Coxiella burnetii, the causative agent of Q Fever.
COORDINATORS OF THIS FACTSHEET
DVM, PhD, ASSOCIATE PROFESSOR OF BACTERIOLOGY AND BACTERIAL DISEASES OF ANIMALS, VICE-PRESIDENT OF THE EU Q FEVER COMMITTEE.
“If you see your ewes or does losing their pregnancies late in the term, or if you’re seeing an unusual number of weak lambs and kids that just won’t thrive, do not simply chalk it up to bad luck. You must suspect abortive agents like Coxiella burnetii. This bacterium is a ‘silent thief’ that hides in the afterbirth and fluids during delivery. But the danger isn’t just to your livestock’s productivity; it is a direct threat to you and your family. When an infected animal gives birth, billions of these germs are released into aerosols and the dust of your barn. You, your spouse, your children and visitors can breathe them in without ever knowing it. In humans, this can lead to severe flu-like symptoms, pneumonia, or even long-term heart issues. Protecting your farm’s future starts with a diagnosis—because you can’t manage a risk you haven’t identified.”
DVM, PhD, RAMON Y CAJAL RESEARCHER AT THE SPANISH MINISTRY OF SCIENCE AND INNOVATION AND FULL PROFESSOR AT THE CEU CARDENAL HERRERA UNIVERSITY IN VALENCIA, SPAIN; PROVAGINBIO RESEARCH GROUP.
“The impact of coxiellosis on female fertility should not be overlooked. Although this is well known in cattle, there are several studies on the subject in sheep and goats. Scientifically, we have repeatedly confirmed the negative impact of abortion caused by Coxiella burnetii on the vaginal microbiota in abortion outbreaks in small ruminants, in relation with several infertility biomarkers. Furthermore, we also observed early embryonic resorption in sheep infected with C. burnetii. Early diagnosis will allow to implement control and prevention strategies that will help reduce the economic impact on your herd/flock.”
LATE PREGNANCY ABORTIONS: A MAJOR CLINICAL SIGN OF INFECTION
Coxiella burnetii mainly causes abortions, premature births, neonatal death, the birth of weak animals and/or embryonic resorption. Goats are considered more sensitive to an infection than sheep, and especially in goat herds, series of abortions are not unusual[3,4].
In healthy flocks/herds, the proportion of aborting ewes/does is generally less than 2%. An abortion rate above 2-5% suggests that an established disease may be present on the farm[5].
Coxiellosis is one of the infectious diseases to be investigated first in the context of abortions, together with chlamydiosis, toxoplasmosis and any other relevant pathogen depending on the local context (salmonellosis, border disease, brucellosis…). Many studies have shown that small ruminants can be exposed to C. burnetii in high rates all over Europe (Spain, Netherlands, France and Portugal for instance)[6,7,8,9].
When abortion levels exceed 5%, or when several abortion events occur within a short time (e.g., 2 weeks) or a given location (e.g., pen or farm), it is urgent to refer to the farm’s practitioner, to launch a C. burnetii investigation.
When abortions, premature births, stillbirths and weak offspring are present in a flock/herd (the so-called APSW Complex), coxiellosis should always be suspected, even if that given farm has implemented vaccination.
DID YOU KNOW? Although tick-borne transmission to domestic animals and humans is possible, it does not appear to play a significant role in this domestic cycle. Conversely, it seems to play a relevant role in maintaining the infection among wildlife[10].
OTHER DESCRIBED OR SUSPECTED SIGNS
There is limited evidence to support that clinical signs other than late abortions should lead to suspect coxiellosis in a flock/herd.
However, in the Netherlands, in C. burnetii positive goat herds (before vaccination became compulsory at national level), an increased incidence of metritis has been observed, while apparently healthy kids born from infected dams were dying as well[11].
Another study shows that high C. burnetii shedder goats have a reduced milk yield (about 17%) in comparison with low shedder goats (loss of 0,53 L/day for a daily production of 3.03 L/day)[12]. However, reduced milk production is not considered a warning sign of coxiellosis.
A LIMITED AWARENESS AMONG EUROPEAN SHEEP & GOAT FARMERS
A European survey on Q Fever perception by farmers has been conducted in 2024[13], the first one on this subject. It included nearly 200 sheep and 180 goat farmers, from France, Spain, Italy, the UK and the Netherlands. In sheep, abortion ranked number one (#1) health problem in the UK, #2 in Spain and France, #3 in Italy. However, over 60% of respondents declared themselves as unaware of Q Fever in the UK, Spain and Italy, and 52% in France. In goats, abortion ranked #1 in the Netherlands and Spain, #4 in France and # 5 in Italy. Still, over 50% of respondents declared themselves unaware of Q Fever in France, Spain and Italy (and 30% in the Netherlands). This highlights the limited knowledge on Q Fever among small ruminant farmers in Europe, and justifies effort to increase awareness on the infection, its impact on farms’ productivity and the related health risks, also for humans, which are precisely among the aims of the European Q Fever Committee.
NOTE: Goats can be chronically infected and become potential shedders of the bacteria via the vaginal mucus and milk, at subsequent pregnancies after infection. This highlights the importance of adopting sanitary and prophylactic measures, in order to limit the transmission of the infection[14].
CRITERIA FOR SUSPECTING COXIELLOSIS IN SMALL RUMINANTS
Clinical signs of the APSW Complex (abortions, premature births, stillbirths, weak offspring) are the main warning signs in small ruminants[15].
DID YOU KNOW? In the period 1990-2022, studies investigating 81 large human Q Fever outbreaks with 8,976 total cases across 27 countries have been published in international scientific journals. Almost half of these outbreaks (40/81) were directly related to exposure to sheep and goats and/or their products![16].
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