Introduction
Q fever is a bacterial infection caused by the coxiella burnetii bacteria. It causes flu-like symptoms such as a high temperature, muscle pain and headaches. Read more about the symptoms of Q fever.
In most people, the symptoms of Q fever will get better without treatment within two weeks. Antibiotics may be recommended if your symptoms are severe or do not improve. A less common, long-term form of Q fever requires antibiotics for several years. Read more about treating Q fever.
The ‘Q’ in Q fever stands for ‘query’. This is because when the infection was first indentified, its cause was unknown. The cause is now understood but the name has remained the same.
Catching Q fever
Q fever is spread to humans from animals, most commonly livestock such as sheep, goats and cattle. Very rarely, it can spread directly from human to human, usually during sexual intercourse. Read more about the causes of Q fever.
In England, people who are most at risk of getting Q fever are those whose occupation brings them into close contact with livestock, including:
- farmers
- stablehands
- abattoir workers
- meat packers
- veterinarians
In the UK, around 50 cases of Q fever are reported every year. However, the actual figure may be much higher because Q fever often causes only mild symptoms that can be mistaken for flu.
Q fever is more common during the lambing season (around January to April), but can occur at any time of year. It is also more common in agricultural areas.
Types of Q fever
There are two main types of Q fever:
- the most common and least serious type is called acute Q fever
- the less common but more serious type is called chronic Q fever
Acute Q fever
Acute means short-term. Acute Q fever causes flu-like symptoms that last for a couple of weeks. Less commonly, acute Q fever can cause mild pneumonia (inflammation of the lungs), and mild hepatitis (inflammation of the liver).
Chronic Q fever
Chronic means long-term. In some cases, the symptoms of Q fever can last for six months or longer. This is called chronic Q fever. People with chronic Q fever will need to take antibiotics for at least three years to prevent the infection from reoccurring.
It is also possible for chronic Q fever to cause inflammation of the inner lining of the heart (endocarditis). Endocarditis is potentially very serious. Left untreated, it can affect the normal workings of the heart and lead to heart failure. With treatment, it is estimated that less than 1 in 10 people with endocarditis caused by Q fever will die.
Vaccination
There is no vaccine for Q fever available in the UK.
A vaccine for Q fever has been produced in Australia, but it has not been licensed for use here.
However, the Health and Safety Executive is currently working with the Joint Committee on Vaccinations to determine whether a routine vaccination should be made available to people in high-risk occupations.
Read more about preventing Q fever.
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Symptoms
Acute Q fever
Q fever is usually a short-term (acute) condition.
The symptoms of acute Q fever usually develop two or three weeks after the initial infection, although it can be as little as two days or as long as 40 days after. The time it takes for symptoms to develop after infection is known as the incubation period. Symptoms include:
- high temperature (fever) of 38°C (100.4°F) or over
- severe headaches
- muscle and joint pain
- sweats
- sore throat
- sensitivity to light
- weight loss
- a skin rash (less commonly)
These symptoms can come on quite suddenly and usually last up to two weeks.
In a few cases, acute Q fever can also cause pneumonia (inflammation of the lungs) and hepatitis (inflammation of the liver).
The pneumonia caused by Q fever is usually mild.
Symptoms include:
- a dry cough
- a sharp chest pain that is made worse by breathing deeply, coughing or laughing
As with pneumonia, the hepatitis caused by Q fever is usually mild and many people will experience no obvious symptoms. Yellowing of your skin and the whites of your eyes (jaundice) is rare.
Chronic Q fever
In some cases, Q fever can become a long-term (chronic) condition. In chronic Q fever, the symptoms can last six months or longer after an acute Q fever infection. You may feel tired and generally unwell for months.
In a few rare cases, chronic Q fever can cause inflammation of the inner lining of the heart (endocarditis). This is more likely to occur if you already have damage to your heart valves, or if you have had heart bypass surgery.
Endocarditis can cause the following symptoms:
- chills
- night sweats
- fever
- shortness of breath
- a cough
- unexplained weight loss
Read more about endocarditis.
Q fever in pregnancy
If you catch Q fever while you are pregnant, it often causes no symptoms. However, it can affect your unborn baby whether you experience any symptoms or not. It can cause:
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Causes
Q fever is caused by bacteria known as coxiella burnetii (or c. burnetii). 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.
The most commonly affected animals, and those that pose the biggest risk to humans, are:
- sheep
- cows
- goats
- domesticated pets, such as dogs, cats and guinea pigs
Most animals with Q fever do not experience any symptoms, so it can be difficult to tell if an animal is infected. However, the bacteria can cause an increase in miscarriages among an infected herd of cows or flock of sheep.
The bacteria can be released by an infected animal through its:
- milk
- blood
- urine
- 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. For example, it is estimated that one gram of infected placenta contains enough bacteria to infect 100 million guinea pigs with Q fever.
How Q fever is spread to humans
Q fever can be spread to humans in a number of different ways. The c. burnetii bacteria are tough and can survive in the outside environment for up to six months. They can 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 that has not been treated with heat to kill off bacteria)
It is possible that a bite from an infected tick could lead to Q fever, but there have not been any recorded cases of this in the UK.
Human to human transmission
It is possible, but very rare, to catch Q fever from another person.
Most experts believe that Q fever can only be transmitted from one human to another through:
- sexual intercourse
- by a pregnant woman passing on the infection to her unborn child
Chronic Q fever
It is unclear why some people go on to develop the long-term (chronic) form of Q fever. Most cases of chronic Q fever develop in people with a pre-existing health condition, which makes them more vulnerable to infections. These health conditions include:
Vulnerability to infection is higher in people who have a weakened immune system, caused either by a health condition, such as HIV or AIDS, or as a side effect of certain medical treatments, such as chemotherapy or long-term steroid use.
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Treatment
In most people, the symptoms of Q fever will get better without treatment within two weeks.
You may need treatment with antibiotics if your symptoms:
- are severe
- do not improve
- return after your initial infection
Acute Q fever
If you have short-term (acute) Q fever, you may be prescribed doxycycline or tetracycline.
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 that you finish the whole course, even if you feel better. This will ensure that all the bacteria have been killed, preventing the infection from reoccurring.
Chronic Q fever
Long-term (chronic) Q fever can be difficult to treat because the c. burnetii bacteria, which cause Q fever, can be resistant to antibiotics. This means the antibiotics can’t kill them.
You will need to take a combination of antibiotics, such as doxycycline and chloroquine.
It is recommended that you take these for at least three years. However, the infection returns in more than half of people.
You may need to have blood tests every three to six months while you are being treated to check that the treatment is working.
If you have inflammation of the lining of your heart (endocarditis), you will need to be treated in hospital. Read more about treating endocarditis.
Pregnancy and breastfeeding
If you are pregnant or breastfeeding and have Q fever you may be referred to a doctor who specialises in infectious diseases. They will advise you about your treatment.
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Q&A
Why should pregnant women avoid sheep during the lambing season?
Some infections can pass from sheep to humans. If a pregnant woman becomes infected, it can harm her and her unborn baby's health.
If you’re pregnant, avoid close contact with sheep during the lambing season, which runs from January to April.
Infections that can cause problems
Infections that can cause female sheep (ewes) to miscarry include:
- chlamydiosis (enzootic abortion of ewes or EAE),
- toxoplasmosis, and
- listeriosis.
Another infection, Q fever, can also cause serious illness in pregnant women, although it rarely harms the unborn baby.
The risks are low
These infections are uncommon in sheep, and very rare in humans. The number of human pregnancies affected by contact with sheep is extremely small.
Although the risks are low, avoid close contact with sheep during lambing.
Advice for pregnant women
To avoid the risk of infection, pregnant women should follow the advice below:
- Don't help to deliver lambs or milk ewes.
- Avoid contact with aborted or newborn lambs, and with the afterbirth.
- Avoid handling clothing, boots and other items that have been in contact with ewes or lambs.
Farmers are responsible for minimising the risk of pregnant women getting into close contact with sheep. This includes members of their family, the public and professional staff who visit their farms.
When to get medical advice
Seek medical advice if you’re pregnant and:
- you get a high temperature or flu-like symptoms, or
- you think you may have got an infection from a farm environment.
What infections can animals pass to people?
Animals can pass many infections to people, although this route of infection is rare. The medical name for these infections is zoonoses. They can be passed on in various ways, and different animals can pass on different infections.
Infections caused by parasites, insects and fungi
Animals can pass infections on through parasites, infected insects and fungi. Examples are:
- toxocariasis (toxocarosis) – caused by swallowing soil contaminated with roundworm parasite eggs passed into the soil through infected dogs' and cats' stools (faeces)
- toxoplasmosis – caused by a parasite found in infected cats’ stools, undercooked or raw meat (mainly pork or lamb) and raw cured meat (such as parma ham or salami)
- giardiasis – most commonly caused by drinking water contaminated with stools containing parasites
- Lyme disease – passed on by a bite from a tick that’s bitten an infected animal or bird
- ringworm - a fungal skin infection sometimes passed on from infected pets such as dogs and cats
Infections caused by food and water contaminated with bacteria
Infections can also be passed from animals to people through contaminated food and water.
Food poisoning can be caused by campylobacter bacteria found in:
- undercooked and raw meat, particularly poultry such as chicken
- unpasteurised milk
- untreated water
Salmonella bacteria also cause food poisoning and can be found in:
- raw meat and poultry
- unpasteurised milk
- eggs and raw egg products
Salmonella can also be passed on through contact with stools from infected animals such as reptiles.
Bacteria that less commonly cause food poisoning include:
- E.coli (Escherichia coli) – found in undercooked meat (particularly beef) and unpasteurised milk
- listeria – causes listeriosis and is found in unpasteurised cheeses (such as brie, camembert and blue cheese), cooked sliced meats, pâté, smoked fish and chilled ready meals
Infections rarely or not found in the UK
Some human infections from animals are rarely found in the UK, including:
- chlamydiosis – caused by close contact with infected sheep during the lambing season
- leptospirosis – caused by contact with urine from infected animals, such as rats and cattle, or contaminated water
- Q fever – caused by contact with animals, most commonly sheep, cattle and goats, or contaminated soil, dust, hay or straw
- tapeworm infections – caused by swallowing tapeworm eggs or larvae in food or water contaminated by human or animal stools
- tetanus – caused by bacteria in contaminated soil or manure entering a wound and by animal bites
These infections are not currently found in the UK:
- avian flu (bird flu) – caused by close or direct contact with infected birds
- rabies – caused by a bite from an infected animal, usually a dog
Pregnancy
If you’re pregnant, it’s important to know that some infections from animals can damage your unborn baby or make you ill.
How can I avoid catching an infection from an animal?
There are several ways you can reduce your risk of catching an infection from an animal. The medical name for infections that animals can pass to people is zoonoses.
Contact with animals
To reduce your risk of infection from an animal:
- avoid contact with infected animals
- avoid direct contact with animals' faces, for example, do not kiss your pet
- avoid direct contact with animals' stools (faeces)
If you have a pet, follow your vet's advice about treating it regularly for infections such as worms.
Personal hygiene
Wash your hands thoroughly with soap and water:
- before and after preparing or handling any food, including raw meat or fish
- before eating
- after using the toilet
- after close contact with animals, for example, pets or farm animals
- after contact with animal stools
Preparing and handling food
Take care when preparing and handling food:
- cook meat or fish thoroughly until it's cooked all the way through and the juices run clear
- avoid eating raw or undercooked meat and fish
- wash raw vegetables and fruit before you eat them
- store food properly, for example, by keeping your fridge and freezer at the correct temperatures
- use food by its 'use by' date
- clean your work surfaces and kitchen equipment thoroughly
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