Q Fever: Causes, Symptoms, Transmission, Diagnosis, Treatment, and Prevention

Article Summary

Q fever is a bacterial infection caused by Coxiella burnetii. People usually become infected by breathing in contaminated dust from infected animals, especially cattle, sheep, and goats. Some people have no symptoms, while others develop fever, headache, muscle pain, and severe tiredness. Most recover completely, but Q fever can sometimes cause pneumonia, liver inflammation, or long-term health problems. Diagnosis involves blood tests, and the antibiotic doxycycline is the usual treatment for acute infection. A small number of people develop persistent infection requiring prolonged treatment. Protective measures and vaccination for eligible people in Australia can help prevent Q fever.

Cite as: Q Fever: Causes, Symptoms, Transmission, Diagnosis, Treatment, and Prevention. Brisbane (AU): Exon Publications; 2024 Jul 16 [updated 2026 Nov 03].

Introduction

Q fever is an infectious disease that can affect people who work with animals or live near areas where infected animals are present. It occurs in many parts of the world, including Australia, where it is an important occupational health concern. Although its name includes the word "fever," the illness can affect several organs and occasionally cause serious complications. The infection is often overlooked because its early symptoms resemble those of other illnesses. Understanding how Q fever spreads, who is at risk, and why early treatment matters can help reduce its health effects.

Coxiella burnetii, the bacterium responsible for Q fever, can survive and multiply inside macrophages, immune cells that normally help destroy invading microorganisms.

What Is Q Fever?

Q fever is a disease caused by Coxiella burnetii, a bacterium that can infect humans and many types of animals. It belongs to a group of infections called zoonotic diseases, meaning they can spread from animals to humans.

The bacterium can survive for long periods in the environment, particularly in dried animal material and contaminated dust. It is also highly infectious, meaning that breathing in a small number of bacteria may be enough to cause illness.

Once inside the body, the bacteria enter certain immune cells, including cells called macrophages. These cells normally help destroy germs, but C. burnetii can survive and multiply inside them. The body's immune response then produces many of the symptoms associated with Q fever (1).

What Causes Q Fever and How Does It Spread?

Q fever develops when a person becomes infected with C. burnetii. Cattle, sheep, and goats are important sources, although other domestic and wild animals can carry the bacteria.

Infected animals may release large numbers of bacteria through their birth fluids and placentas. Bacteria can also be present in urine, feces, and milk. These materials may contaminate the surrounding environment.

The main route of human infection is breathing in contaminated dust or tiny airborne particles. This can happen during animal births, farming activities, shearing, meat processing, or cleaning areas contaminated by infected animals.

Wind can carry contaminated dust beyond farms, so direct contact with animals is not always necessary. Drinking unpasteurized milk is another possible source of exposure, although inhalation is the main recognized route.

Q fever does not normally spread from person to person. Therefore, people with Q fever generally do not need isolation to prevent transmission to others (1).

Who Is Most at Risk of Q Fever?

Anyone exposed to contaminated animal material may develop Q fever. However, the risk is higher in certain occupations and environments.

People at increased risk of exposure include:

• Farmers and livestock handlers


• Veterinarians and veterinary nurses


• Abattoir and meat-processing workers


• Sheep shearers and wool-industry workers


• Animal transport workers


• Wildlife carers


• People living near livestock farms or contaminated environments

Some people also face a greater risk of serious complications after infection. These include individuals with heart valve disease, abnormal blood vessels, vascular grafts, or weakened immune systems. Infection during pregnancy can also cause important health risks (2).

What Are the Symptoms of Q Fever?

Many people infected with C. burnetii develop no noticeable symptoms. Others experience an illness that resembles influenza.

Symptoms usually begin about two to three weeks after exposure, although the timing can vary.

Common symptoms include:

• High fever and chills


• Severe headache


• Marked tiredness


• Muscle and joint pain


• Sweating


• Dry cough


• Loss of appetite


• Nausea or abdominal discomfort

Some people develop pneumonia, an infection or inflammation affecting the lungs. Others develop hepatitis, which means inflammation of the liver. Liver inflammation may be detected through blood tests even when there are few obvious liver-related symptoms.

The early symptoms can resemble those of influenza. However, influenza is caused by a virus, while Q fever is caused by bacteria and requires a different treatment approach.

Most people with acute Q fever improve over several weeks, although tiredness can continue during recovery (2).

What Is the Difference Between Acute and Chronic Q Fever?

Q fever can cause an acute illness or, less commonly, a persistent infection.

Acute Q fever is the initial infection. It may cause fever, headache, muscle pain, pneumonia, or liver inflammation. Many cases are mild, and some people recover without developing noticeable symptoms.

Chronic Q fever, also called persistent focal Q fever infection, occurs when the bacteria remain active in a particular part of the body. It develops in fewer than 5% of infected people.

The most common serious form affects the inner lining or valves of the heart, producing a condition called endocarditis. Persistent infection can also affect blood vessels, particularly in people with an aneurysm or an artificial vascular graft.

Chronic Q fever may develop months or years after the original infection, sometimes without a previously recognized acute illness. It requires specialist assessment and prolonged antibiotic treatment (2, 3).

How Is Q Fever Diagnosed?

Q fever is diagnosed using the person's symptoms, possible exposure history, and laboratory tests.

A clinician may suspect Q fever when someone develops an unexplained fever after contact with livestock or visits to an area where infected animals may be present.

Two main laboratory methods are used.

Antibody tests: These blood tests look for proteins made by the immune system in response to C. burnetii. Antibodies may not be detectable during the early days of illness. A second blood sample taken several weeks later may be needed to confirm a recent infection.

Polymerase chain reaction (PCR): This test looks for bacterial genetic material in the blood. It is particularly useful early in the illness, before antibody levels rise. Its ability to detect infection decreases after antibiotic treatment begins.

Doctors may also request liver function tests, blood counts, or imaging when complications are suspected.

Because early tests can be negative, treatment for suspected acute Q fever should not be delayed while waiting for laboratory confirmation (4).

How Is Q Fever Treated?

Q fever is treated with antibiotics that act against C. burnetii.

Treatment of acute Q fever: Doxycycline is the recommended first-line antibiotic for most adults with symptomatic acute Q fever. The usual treatment course is 14 days.

Treatment is most effective when started early, ideally within the first three days after symptoms begin. It can shorten the illness and reduce the risk of serious complications.

Even if initial blood tests are negative, treatment may begin when the symptoms and exposure history strongly suggest Q fever.

Treatment during pregnancy: Q fever during pregnancy requires special care because infection may increase the risk of miscarriage, premature birth, or other pregnancy complications.

Trimethoprim-sulfamethoxazole may be recommended instead of doxycycline, with treatment decisions depending on the stage of pregnancy. Specialist advice is important because medication safety and treatment duration require careful consideration.

Treatment of chronic Q fever: Persistent infection requires a much longer treatment course. People with Q fever endocarditis or vascular infection are commonly treated with doxycycline and hydroxychloroquine for at least 18 months, with the duration adjusted according to clinical findings.

Specialist monitoring is essential because treatment response can be slow and complications may be serious (5).

Can Q Fever Cause Long-Term Fatigue?

Some people continue to experience severe tiredness long after their acute Q fever infection has resolved. This condition is called Q fever fatigue syndrome.

Symptoms may include persistent exhaustion, muscle pain, poor concentration, disturbed sleep, and reduced ability to carry out daily activities.

Q fever fatigue syndrome is different from chronic Q fever. In fatigue syndrome, there is usually no evidence of an ongoing active bacterial infection. The exact cause remains uncertain, although changes in immune responses may contribute.

Prolonged antibiotic treatment has not been established as an effective treatment for Q fever fatigue syndrome. Care generally focuses on assessing symptoms, excluding other medical conditions, and providing appropriate support (3).

Can Q Fever Be Prevented?

Prevention focuses on reducing exposure to C. burnetii, particularly in workplaces involving livestock or animal materials.

Useful protective measures include:

• Wearing suitable respiratory protection when exposed to potentially contaminated dust


• Using gloves and protective clothing when handling animal birth materials


• Washing hands after handling animals or contaminated equipment


• Cleaning and managing animal waste safely


• Avoiding unpasteurized milk


• Following workplace infection-control procedures

Vaccination: Australia has a Q fever vaccine for people at increased risk of exposure. It is recommended for eligible individuals aged 15 years and older, particularly those working in livestock and related industries.

Before vaccination, people must undergo blood and skin testing to determine whether they have previously been exposed to C. burnetii. Vaccinating someone with previous infection or vaccination may cause a strong local reaction.

The vaccine is not routinely available in many other countries, including the United States.

Vaccination and appropriate workplace protection can significantly reduce the risk of Q fever among people with repeated occupational exposure (6).

What Is the Outlook for People With Q Fever?

Most people with acute Q fever recover completely, particularly when the infection is recognized and treated early.

However, recovery may take several weeks, and some people experience longer-lasting fatigue. A small number develop persistent infection affecting the heart or blood vessels.

People with heart valve problems, vascular abnormalities, or weakened immune systems may need follow-up blood tests and medical assessments after acute infection. These checks help detect persistent infection before serious complications develop.

Anyone who develops an unexplained fever after possible livestock or animal-related exposure should seek medical assessment and mention the exposure history.

Conclusion

Q fever is a bacterial infection usually acquired by breathing in dust contaminated with material from infected animals. It can cause fever, headache, severe tiredness, pneumonia, and liver inflammation. Doxycycline is the recommended treatment for most people with symptomatic acute Q fever. Although most recover completely, some develop persistent infection or long-term fatigue. People with certain heart or blood vessel conditions require closer monitoring because of their greater risk of complications. Vaccination for eligible people in Australia, protective equipment, and safe animal-handling practices are important ways to reduce the risk of infection.

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References

1. Tolpinrud A, Chaber AL, Wiethoelter AK, Devlin JM, Stenos J, Firestone SM, et al. Q fever in humans, domestic animals and wildlife. Microbiol Aust. 2025;46(1):7–12. https://doi.org/10.1071/MA25005


2. Centers for Disease Control and Prevention. Clinical signs and symptoms of Q fever. Atlanta (GA): CDC; 2025 Jan 30. https://www.cdc.gov/q-fever/hcp/clinical-signs/


3. Mezouar S, Desnues B, Bechah Y, Bardin N, Devaux C, Mege JL. Pathogenicity and virulence of Coxiella burnetii: focus on Q fever. Virulence. 2025;16(1):2495842. https://doi.org/10.1080/21505594.2025.2495842


4. Centers for Disease Control and Prevention. Clinical and laboratory diagnosis for Q fever. Atlanta (GA): CDC; 2024 May 15. https://www.cdc.gov/q-fever/hcp/diagnosis-testing/


5. Centers for Disease Control and Prevention. Clinical guidance for Q fever. Atlanta (GA): CDC; 2025 Mar 5. https://www.cdc.gov/q-fever/hcp/clinical-guidance/


6. Sam G, Stenos J, Graves SR, Rehm BHA. Q fever immunology: the quest for a safe and effective vaccine. NPJ Vaccines. 2023;8(1):133. https://doi.org/10.1038/s41541-023-00727-6

This article is part of the 'Public Education Series' initiative by Exon Publications.

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