Q fever is an infection caused by Coxiella burnetii (C. burnetii) bacteria.
The infection is carried by animals, most commonly sheep, cattle and goats.
Read more about the symptoms of Q fever.
How Q fever is transmitted
Q fever can be spread to humans from livestock, such as sheep, cows and goats.
People most at risk of infection are those who work closely with livestock such as:
- abattoir workers
- meat packers
Coxiella burnetii bacteria are present in the afterbirth, birth fluids, milk, urine and faeces of infected animals.
You can become infected by breathing in contaminated dust, or by coming into contact with the placenta or amniotic fluid of an infected animal.
Read more about the causes of Q fever.
Diagnosing Q fever
Q fever is usually diagnosed with a blood test.
If Coxiella burnetii bacteria enter your blood, your immune system (the body’s natural defence) will produce a particular antibody (protein) to kill them. These antibodies should show up in your blood 2-3 weeks after you have been infected.
Treating Q fever
Q fever usually lasts for about two weeks and gets better without treatment. You may need antibiotics if your symptoms are severe or if they don't improve after a few weeks.
Less commonly, the symptoms of Q fever can last six months or longer. In such cases, you may need to take antibiotics for several years to prevent the infection reoccurring.
Read more about treating Q fever.
A vaccine for Q fever isn’t available in the UK. A vaccine has been produced in Australia, but has not been licensed for use in this country.
Read more about preventing Q fever.
Q fever is usually a short-term infection that lasts about two weeks.
Symptoms usually develop 2-3 weeks after the initial infection, although they can take as little as two days or as long as 40 days.
Symptoms of Q fever include:
- high temperature (fever) of 38°C (100.4°F) or more
- severe headaches
- muscle and joint pain
- sore throat
- sensitivity to light (photophobia)
- weight loss
- a skin rash (very unusual)
The symptoms can come on suddenly and usually last up to two weeks.
Pneumonia caused by Q fever is usually mild. Symptoms include a dry cough and a sharp chest pain made worse by breathing deeply, coughing or laughing.
As with pneumonia, hepatitis caused by Q fever is usually mild and many people will experience no obvious symptoms.
Long-term Q fever
Occasionally, symptoms of Q fever last six months or longer. This is known as chronic Q fever. You may feel tired and generally unwell for months.
In rare cases, chronic Q fever can cause the inner lining of the heart to become inflamed (endocarditis). This is more likely if your heart valves are already damaged, or if you have had heart valve replacement surgery.
If you get Q fever while pregnant you may not have any symptoms. However, your unborn baby can be affected whether you experience any symptoms or not. It can cause:
Q fever is caused by Coxiella burnetii (C. burnetii) bacteria. The bacteria are usually spread to animals by infected ticks.
Samples of C. burnetii have been found in almost all types of animals, including reptiles and fish.
However, the most commonly affected animals and those that pose the biggest risk to humans are:
- domesticated pets, such as dogs, cats and guinea pigs
Most animals with Q fever don't have any symptoms, so it can be difficult to tell if an animal is infected. However, the bacteria can cause an increase in miscarriages among infected cows or sheep.
The bacteria can be released by an infected animal through its:
- stools (faeces)
- fluids and products produced during birth, such as the afterbirth (placenta)
Birth by-products pose the greatest risk because they contain a high number of C. burnetii bacteria.
How Q fever is spread to humans
Q fever can be spread to humans in a number of ways. The c. burnetii bacteria are tough and can survive in the outside environment for up to six months. They can be spread through:
- breathing in small particles released by infected animals, particularly when animals are being slaughtered or giving birth
- breathing in small particles from contaminated soil, dust, hay, straw bedding or other substances
- infected particles coming into contact with a cut on your skin or the white part of your eyes
- drinking unpasteurised milk from an infected animal (unpasteurised milk is milk not treated with heat to kill off bacteria)
Although it is possible for a bite from an infected tick to lead to Q fever, there have not been any recorded cases of this in the UK.
Human to human transmission
It is possible, although rare, to catch Q fever from another person. Most experts believe Q fever can only be transmitted from one human to another through:
- sexual intercourse
- a pregnant woman passing on the infection to her unborn child
Long-term Q fever
It is not clear why some people go on to develop long-term (chronic) Q fever. Most cases of chronic Q fever develop in people with a pre-existing health condition that makes them more vulnerable to infections. These conditions include:
- coronary heart disease or congenital heart disease, particularly disease that affects the heart's valves, such as narrowing of the valves (stenosis)
- having previously had heart valve replacement surgery
- kidney disease
- cancers that affect the blood, such as lymphoma and leukaemia
People with a weakened immune system are more vulnerable to infection. A weakened immune system can either be caused by a health condition, such as an HIV infection, or a side effect of certain medical treatments, such as chemotherapy or long-term steroid use.
Most people who develop Q fever get better without treatment within two weeks.
However, you may need treatment with antibiotics if your symptoms are severe, do not improve or reoccur after the initial infection.
If you are diagnosed with Q fever, you may be prescribed antibiotics, such as [doxycycline] or [co-trimoxazole].
You will need to take these for 7-14 days and for at least three days after your fever has improved.
If you are prescribed antibiotics, it is important you finish the whole course even if you feel better. This is to ensure all bacteria have been killed, preventing the infection from reoccurring.
Long-term Q fever
Q fever that lasts for a prolonged period of time (chronic Q fever) can be difficult to treat. This is because the C. burnetii bacteria which cause Q fever can be resistant to antibiotics (antibiotics are unable to kill them).
If you have chronic Q fever, you will need a combination of antibiotics. You will probably be advised to take these for at least 18-36 months. However, the infection returns in more than half of those who complete such a long course of treatment.
You may also need to have blood tests every 3-6 months while being treated to check the treatment is working.
If the lining of your heart is inflamed (endocarditis), you will need hospital treatment. Read more about treating endocarditis.
If you work with animals, your employer must take preventative measures to reduce your risk of getting Q fever.
For example, they must ensure all animal birth products are disposed of properly and access to infected animals is restricted.
You can also reduce your risk of getting Q fever by not drinking unpasteurised milk and dairy products, and by not touching anything that may have been in contact with animal blood, stools (faeces) or urine.
People particularly vulnerable to infection should avoid occupations that carry a high risk of exposure to Q fever. For example:
- livestock workers
- abattoir workers
- meat packers
- vets and veterinary assistants
People vulnerable to Q fever include:
- those with a history of heart valve disease
- those with a weakened immune system
- pregnant women
Pregnant women should avoid coming into contact with sheep and lambs during lambing season (January to April).
If you are pregnant and come into contact with sheep during lambing, the health of your baby may be at risk. This is because Q fever and other sheep-borne infections can cause miscarriages or stillbirths.
To reduce any risk of developing infections, it is recommended pregnant women should avoid:
- helping lamb or milk ewes
- coming into contact with aborted or newborn lambs or with the afterbirth
- handling clothing, boots and other items that have come into contact with ewes or lambs
For more information, see [why should pregnant women avoid sheep during the lambing season?]