Q fever story map

In humans, Q fever exhibits a wide spectrum of clinical manifestations, either acute (symptomatic primary infection) or persistent focalised infections, formerly known as chronic Q fever. More than half of infected people do not show symptoms. For those who do, Q fever can vary in severity, from a mild illness to a more severe and potentially lethal disease.

The  incubation period  is variable, ranging from 1 to 6 weeks.  

In approximately 40% of infections, acute Q fever manifests with flu-like symptoms: high fever (which often starts abruptly), severe headache, muscle pain, discomfort, sore throat, chills, sweats, non-productive cough and nausea. The acute form is often self-limiting, with recovery occurring within a month. Complications may arise in 2% of infected persons, and include:  

• Hepatitis
• Pneumonia

Acute Q fever in pregnant women, especially during the first trimester, may result in:  

• Premature delivery
• Low birth weight
• Abortion
• Stillbirth

Nevertheless, the impact of Q fever on pregnancy outcomes remains unclear.  

Persistent focalised infections affect 1 to 5% of infected individuals and can appear months or years after the initial infection, regardless of whether an acute form occurred. They may result in: 

• Endocarditis
• Vascular infections

Other, less frequent manifestations include: 

• Chronic fatigue syndrome
• Neurological issues
• Osteo-articular infections
• Pulmonary pseudotumours

Q fever is usually manageable with antibiotics. It rarely leads to fatal outcomes if not treated. 

Men are almost twice as likely as women to develop the disease, potentially due to the protective effects of female hormones. Adults have five times the risk compared to children under 15, with increased risk in males over 50 and those with cardiovascular conditions such as  valvulopathies , vascular prostheses and vascular aneurysms.  

While Q fever poses minimal threat to most individuals, those involved with livestock or animal-derived products are at higher risk of exposure to C. burnetii. This includes:  

• Farm workers
• Slaughterhouse workers
• Meat-packing plant employees
• Veterinarians
• Wool workers
• Laboratory personnel 

Urban individuals without prior exposure may be more vulnerable to Q fever than rural individuals, who often maintain immunity from frequent exposure to infected animals or contaminated products.  

In animals, clinical signs are primarily reported in pregnant goat, sheep and cattle, and they include: 

• Abortion (mostly occurring late in gestation)
• Stillbirth
• Delivery of small or weak offspring

Although widespread abortions can occur in sheep and goats, they are not observed in cattle, where infertility or sub-fertility is hypothesised, but causal evidence has not been reported. Animals that abort due to Q fever usually recover without further complications and do not have subsequent abortions. C. burnetii can persist latently, reactivating and shedding under stress or subsequent pregnancies. 

Most animal species can act as carriers and shedders of C. burnetii, with occasional reports of clinical manifestations such as in cats and fur seals.

Burden of disease

The economic repercussions of Q fever could be significant.  

The world’s largest documented Q fever epidemic occurred in the Netherlands from 2007 to 2010, linked to intensive dairy goat farming. This  outbreak  resulted in nearly 4,000 human cases, economic losses of 250 to 600 million euros and significant disruption in the dairy sector. In addition, persistent focalised infections of Q fever also posed long-term public health and economic burdens. 

 Community-acquired  Q fever outbreaks, caused by the spread of the bacterium from animals to humans, pose the greatest public health concern due to their potential to impact a large number of people.

Notably, Q fever is classified as a Multiple Species Infection by the World Organisation for Animal Health (WOAH), and it is reported in a wide range of hosts.  

The primary  reservoir  species in Europe are: 

• Sheep
• Goat
• Cattle

In addition, other species may play a minor role in maintaining the pathogen in the environment, for example: 

• Pet animals (such as dogs and cats)
• Other mammals (such as camelids)
• Birds
• Arthropods (ticks)

However, there are few available data supporting their role in the epidemiology of the disease in Europe. 

Infected animals can excrete the bacterium through various tissues and fluids; thus, C. burnetii can be found in:

• Vaginal secretions
• Placenta
• Aborted foetuses and foetal membranes
• Faeces
• Urine
• Milk
• Blood (in the early phase of infection)

In cattle, sheep and goat herds affected by Q fever, bacteria are shed through multiple routes, although simultaneous shedding into milk, faeces, and vaginal mucus is considered rare. Vaginal shedding is the most frequent event, especially during birthing, where levels can exceed 10,000 bacteria per swab, and the placenta may release up to one billion bacteria per gram.  

The shedding pattern can persist for several months, with intermittent episodes observed in convalescent and even asymptomatic herds.  

Therefore, C. burnetii can also be found in contaminated: 

• Farm environments (straw, enclosures, pastures)
• Manure (bedding, pile)
• Sheep wool
• Fomites (farm equipment and vehicles, laundry and clothing)

C. burnetii bacteria are most commonly and abundantly found in contaminated dust, in which concentration can exceed 100 million bacteria per sampling unit. 

The ability of this pathogen to infect a wide range of wild and domestic hosts significantly increases the risk of disease spread between farms and surrounding wildlife, contributing to its widespread presence in the environment.

Humans are accidental hosts, while cattle, sheep and goat (especially the latter two species), are the primary domestic animal reservoirs. In the temperate European climate, the incidence of Q fever typically peaks during spring and early summer, coinciding with the birthing season of these animals.

Airborne transmission 

In humans, inhalation is the major mechanism of transmission of C. burnetii.  

The spore-like forms can remain infectious for many months in the environment, becoming airborne in the form of  aerosols  or larger dust particles originating from soil, dried animal faeces and other organic material contaminated by the excreta of infected animals. In Europe, contamination most frequently occurs with infected sheep and goats. The dispersion of these particles depends on atmospheric and environmental factors, extending the risk several kilometres from the source.

Moreover, the infection can also be contracted through inhalation of contaminated aerosols or dust originating from contaminated surfaces or objects (fomites), such as: 

• Farm environments (e.g., straw, enclosures, pastures)
• Manure (manure handling, transportation, spreading, anaerobic digester)
• Wool
• Farm equipment (e.g., tractors, manure spreaders, animal transport trucks, waste vehicles for disposal)
• Slaughterhouses and carcass processing facilities
• Dairy and wool industry, tanneries
• Laundry and clothing 

Non-airborne transmission 

Non-airborne transmission routes are possible, though negligible compared to the predominant airborne path.   

Foodborne transmission 

C. burnetii can be found in low quantities in raw milk and related dairy products, but no human cases following consumption of these contaminated foods have been reported. 

Person-to-person transmission 

Direct human-to-human transmission of Q fever is very rare, but some cases have been sporadically reported: 

• Following contact with an infected parturient woman
• Transplacental transmission
• Cutaneous inoculation

Sexual transmission and transmission through tick bites is still uncertain in humans.

Animals can become infected via: 

• Inhalation of contaminated aerosols
• Inhalation of contaminated dust after contact with contaminated material
• Tick bites
• Sexual transmission

As with humans, inhalation of aerosols or dust contaminated by infected body fluids or secretions, such as aborted materials, parturition products, urine and faeces, represents the primary route of transmission.

Ticks may possibly play an additional role in the spread of the disease between domestic and wild animals. 

In ruminants, transplacental transmission may also occur, leading to abortion. The consumption of milk and colostrum is considered a minor route for the transmission of C. burnetii between animals. 

• In 2023, there were 805 confirmed cases of human Q fever, corresponding to a European Union notification rate of 0.19 cases per 100,000 population. This was an increase of 11.5% compared with 2022 (0.17 cases per 100,000 population).
• The overall trend for human Coxiella burnetii infections did not show any significant increase or decrease in the 2019–2023 period.
• In 2023, 17 Member States and five non-Member States reported data for C. burnetii in animals. Cattle and small ruminants were predominantly sampled during clinical investigations and passive monitoring of animals with suspected infection. At the European Union level, among the animals tested using direct detection methods (N=3738), the proportion of positive cases was 4.7% in sheep, 11.2% in goats and 6.0% in cattle. For herds tested using direct detection methods (N=5256), the positive proportion was 23.8% for sheep, 20.0% for goats and 8.5% for cattle. Serological testing revealed that 27.0% of sheep, 25.9% of goats and 6.0% of cattle were seropositive among the 8722 animals tested. At the herd level, 0.75% of sheep flocks, 4.8% of goat herds and 6.4% of cattle herds tested seropositive out of 5429 herds.
• Among other farmed, domestic and wild animals tested (N=528 animals, N=21 herds from nine reporting countries), positivity was reported mainly in Italy, in donkeys, horses, mouflons, water buffalos, dogs and deer. Additionally, Belgium reported one positive deer holding. 

For more information on Coxiella burnetii reported in humans and animals in the EU and other reporting countries in 2023, refer to the  2023 EU One Health Zoonoses Report .

The prevention and control of Q fever relies on a comprehensive “One Health” approach, involving measures to reduce the transmission of the pathogen among animals, humans and in the environment.  

There are several options, although their effectiveness remains largely unassessed. Here is an overview of the measures to be considered.

• Using personal protective equipment (PPE) for farmers, operators and veterinarians, during high-risk activities such as handling abortion products and placentas, managing manure, sheep shearing or cleaning.
• Implementing vaccination protocols in the flocks to reduce the risk of shedding. Vaccination must be authorised by the veterinary authority and performed under strict veterinary supervision.
• Properly managing parturient animals and correctly disposing of birth by-products.
• Performing strict control and quarantine of newly introduced animals, especially during critical periods such as the three months following parturition.
• Properly managing bedding materials, especially in presence of potentially highly contaminated material.
• Applying proper procedures for the sanitization of manure (e.g., covering with tarps for at least 90 days for heat inactivation), avoiding its accessibility to wild animals and minimising the risk of airborne dissemination by spreading manure in rainy and windless conditions.
• Applying good hygienic practices to ensure effective cleaning of livestock facilities.
• Organising continuous  biosecurity  training for farm managers and farm workers.
• Ensuring the strict adherence to appropriate cleaning/disinfection protocols at farm sites open to the public (such as schools/hobby farms).

In the event of abortions, promptly notifying the veterinary authorities and quickly implementing all diagnostic investigations are crucial for the early detection of the infection and thus the swift application of the necessary risk mitigation measures. 

For infected farms, control measures are regulated by national legislation. However, best practices include reinforcing these measures to limit the contamination and dissemination of aerosols and dust in the environment, aiming to reduce the transmission of the pathogen among animals, humans and within the environment.  

Specifically, if a farm open to the public is found to be infected or an outbreak is identified in the vicinity, it is necessary to suspend hosting activities as long as the risk of infection exposure persists. 

• Using personal protective equipment (PPE) during high-risk activities for operators in slaughterhouses, the dairy and wool industry, tanneries.
• Organising continuous biosecurity training for workers at risk. 

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Surveillance in humans

• Commission Implementing Decision (EU) 2018/945 provides the case definitions for a range of infectious diseases, including Q fever.
• Regulation (EU) 2022/2371 lays down the rules on relevant cross-border threats to health involving epidemiological surveillance, monitoring, early warning and actions.
• ECDC collects, analyses and disseminates data on human cases ( ECDC’s Surveillance Atlas of Infectious Diseases ) in compliance with Regulation (EU) 2022/2371 and uses indicator-based surveillance data to produce its  Annual Epidemiological Reports . 

 Surveillance in animals

• Regulation (EU) 2016/429 (the Animal Health Law) lays down the rules for the prevention and control of animal diseases transmissible to animals or humans. This includes notification obligations, diagnostic methods and measures to be applied in case of confirmation of disease.
• Commission Implementing Regulation (EU) 2018/1882 lists Q fever as a Category E disease for ruminants (Bison ssp., Bos ssp., Bubalus ssp., Ovis ssp., Capra ssp.). Therefore, in accordance with CIR (EU) 2020/2002, Member States must report annually to the EU Animal Diseases Information System (ADIS), managed by the European Commission, regarding the detection of Q fever for the listed animal species.
• Additionally, Q fever is listed in the WOAH Terrestrial Animal Health Code, requiring Member Countries and Territories to report occurrences of the disease to the WOAH in accordance with international health regulations ( WAHIS )
• A scientific report by EFSA proposes harmonised schemes for the monitoring and reporting of Q fever in animals in the European Union.

Surveillance of  antimicrobial resistance 

• There is no antimicrobial resistance surveillance for Q fever in the EU.

Data on the  prevalence  of animal and human Q fever infections, and on the contamination of food are collected and analysed in the annual  EU One Health Zoonoses report  prepared by EFSA and ECDC. However, since neither surveillance nor reporting of animal Q fever has been harmonised in the EU, data may not be representative of the disease situation in each European country and should not be used for tracking or assessing EU-level temporal and spatial trends. 

EFSA has a crucial role in: 

• Collecting and analysing EU-wide data on the prevalence of C. burnetii in animals, especially sheep, goat, cattle and buffalo.
• Supplying independent scientific advice and assistance on the animal health aspects related to Q fever through EFSA’s Panel on Biological Hazards and EFSA’s Panel on Animal Health and Welfare.
• Supporting European and national risk managers in monitoring and evaluating the prevalence of Q fever in animals and suggesting control measures when needed.
• Developing and assessing tools and measures for the prevention and control of animal disease, particularly aimed at reducing the frequency and impact of abortion episodes, minimising their economic consequences, as well as limiting bacterial shedding by animals to prevent environmental contamination.
• Preparedness and response (EFSA) in the event of clustered human cases, incidents or crises, implementing a reactive One Health approach that coordinates activities across human, animal and environmental health sectors to effectively manage outbreaks. This strategy promotes comprehensive surveillance, rapid response and targeted control measures, acknowledging the interconnected nature of health ecosystems.
• Reporting on surveillance activities carried out within the EU. 

EFSA is assisted by its network on zoonoses monitoring data, a pan-European network of national representatives and international organisations that support EFSA by gathering and sharing information on zoonoses in their respective countries.

For Q fever, there is no European Union Reference Laboratory designated by the European Commission. However, there are national reference laboratories in each Member State.