Q Fever Infection
Questions and answers relating to Q fever infections in humans and animals
What is Q fever? +-
What is Q fever?
Q fever (query fever), also commonly referred to as coxiellosis when occurring in animals, is a disease caused by the bacterium Coxiella burnetii. Coxiella burnetii can infect humans as well as animals. Usually the pathogen is transmitted from animals to humans – therefore Q fever is a zoonosis.
How do I recognize a Q fever infection – What are the signs and symptoms of Q fever?
- Humans (acute Q fever):
Almost all infections in humans manifest as acute Q fever. Due to the unspecific symptoms acute Q fever can easily be mixed up with a common cold. About 1 to 3 weeks after infection clinical symptoms can occur in about 40 % of the infected individuals. These symptoms include:
- Muscle aches und chills
- Severe headaches, often behind the eyes
In about 10 % of the cases patients suffer from atypical pneumonia (inflammation of the lungs) and/or granulomatous hepatitis (inflammation of the liver). Very rarely the infection results in myocarditis (inflammation of the heart muscle), pericarditis (inflammation of the pericardium, the protective sac that surrounds your heart) or meningoencephalitis (inflammation of the brain and its meninges). Important: If there is any clinical suspicion of endocarditis (which among others manifests in changes of the cardiac valves, subfebrile temperature) the possibility of chronic Q fever should always be kept in mind and definitely be checked (see also Category: Long-term Complications What is chronic Q fever?).
- Animals (Coxiellosis):
In particular, ruminants (cattle, sheep, goats) shed the pathogen via birth fluids, milk and faeces. Symptoms can vary considerably. Especially sheep and cattle infected with Coxiella burnetii appear healthy. Pregnant goats, however, often experience abortions late in pregnancy. In general, the following symptoms can be associated with a Q fever infection in ruminants:
- Delivery of weak offspring (lambs, calves)
- Delayed expulsion of the afterbirth
How does an infection with the bacterium Coxiella burnetii resulting in Q fever occur?
People mainly get infected by breathing in dust or airborne droplets containing the bacterium Coxiella burnetii when having direct or indirect contact with infected sheep, cattle and goats as well as their excretions. Pets (dogs, cats) and wildlife can also be infected and shed the pathogen, even though a transmission to humans has been rarely reported. A larger quantity of the infectious pathogen is shed together with birth fluids and the afterbirth of infected ruminants. Even if an infected herd is located several kilometres away, there is still the possibility of being infected when dust carrying the pathogen is spread in the air. The germ can also be transmitted when slaughtering ruminants. However, there is no risk when thoroughly cooked meat is eaten. The risk of being infected by drinking raw milk and eating raw milk products is considered low, but in principle it is possible. (Statement No 018/2010, from March 15, 2010, in German, by Bundesinstitut für Risikobewertung (BfR)). Pasteurisation results in inactivating the pathogen.
Animals are also mainly infected by breathing in dust or airborne droplets containing the pathogen. Especially the acquisition of infected animals or the presence of other herds nearby as well as other pets e.g. cats can be the reason for introducing the germ. Transmission of C. burnetii is also possible by mating. In practice, it is often not feasible to completely retrace the origin of an infection. The latest scientific studies have shown that an infection with C. burnetii has resulted in a subsequent shedding of the pathogen with birth fluids and afterbirth only in the case of pregnant goats. An infection of non-pregnant animals does not seem to lead to the shedding of C. burnetii in a subsequent pregnancy. So far there has been no conclusive evidence whether other pets (e.g. cats) and ticks transmit C. burnetii. However, above all tick faeces are supposed to play an essential role in spreading the pathogen. Infected ticks shed large quantities of the pathogen together with their faeces.
How is Q fever diagnosed and tested?
Q fever is diagnosed by serological testing i.e. testing for antibodies against Coxiella antigens.
The most sensitive test for diagnosing a Q fever infection is the molecular biological analysis (PCR) of afterbirth products, dead lambs/calves or vaginal swabs which detects genetic material (DNA) of the pathogen. Using the PCR assay the shedding of Coxiella burnetii at the present time can be detected. A serological testing for antibodies against Coxiella antigens does not reliably detect an acute infection, however, it reflects a recent infection.
Is Q fever a reportable disease?
Q fever in humans is a reportable disease under the German Infection Protection Act (Infektionsschutzgesetz (IfSG)). According to § 7 Section 1 IfSG direct or indirect detection of Coxiella burnetii indicating an acute infection is reported by name to the local health authorities.
Q fever or the detection of C. burnetii in ruminants is a reportable disease under the German Regulation on Notifiable Animal Diseases (Verordnung über meldepflichtige Tierkrankheiten (TKrMeldpflV)). At the same time the heads of the veterinary research offices (Veterinäruntersuchungsämter), the local veterinary health authorities (Tiergesundheitsämter) or other public or private veterinary medicine research facilities as well as veterinarians identifying reportable diseases when exercising their profession are obliged to immediately report the occurrence of the disease or the pathogen to the authority responsible under federal state law stating the date of detection, the animal species concerned, the animal stock concerned, the district and the district town.
How many Q fever cases are reported in Germany annually?
According to the Annual Report 2018 of the Robert Koch Institute there are significant variations in the number of acute diseases that have been reported since 2001. The cases reported vary between 86 and 416 per year (average number of 233 infections). Due to the known mild symptoms of an acute Q fever an underreporting of cases can be assumed.
According to the Animal Health Annual Report 2018 of the Friedrich-Loeffler-Institut between 146 and 309 infections (average number of 225 infections) with C. burnetii were reported annually in animals or herds between 2014 and 2018. An infection with C. burnetii in animals can occur without obvious symptoms, therefore an underreporting of cases can be assumed.
Questions and answers relating to therapies treating an acute Q fever infection
How is an acute Q fever infection treated? +-
How is an acute Q fever infection treated?
An acute Q fever infection is treated with antibiotics with antibiotic treatment lasting 14 days, with the respective antibiotic tablets being taken (e.g. Doxycyclin).
Children under 8 years and pregnant women (see section pregnancy and breastfeeding) have to be sometimes be treated with antibiotics from other substance groups (e.g. macrolide). It is very important for children to adapt dosing to the child’s weight.
The treatment of animals shedding great amounts of infective organisms during an outbreak of acute Q fever in a herd with the aim to significantly reduce or even to stop the number of pathogens is not possible according to contemporary knowledge. A treatment with Oxytetracycline does not lead to a significant reduction of pathogen shedding. Also, vaccination does not result in a significant reduction of pathogen shedding. However, vaccination against C. burnetii decreases shedding of pathogens of infected animals in the long run. Animals should receive vaccination prophylactically, in order to prevent acute Q fever events in ruminant flocks.
- For vaccination recommendations see section “Where do you find additional information?“ and check STIKO-Vet.