Q Fever: Causes, Symptoms & Prevention Explained

January 11, 2025

“Query fever” or “Q fever” is a rare bacterial infection caused by Coxiella burnetii that generally causes flu-like symptoms (fever, cough, fatigue, headaches, etc.) but may cause serious damage to the heart and other organs. The pathogen resides in the body fluids (urine, milk, amniotic fluid, etc.) of animals like cattle, goats, sheep, etc. Humans acquire the disease when they inhale dust particles contaminated with the bacteria. The disease has acute and chronic manifestations.¹
Most large outbreaks of the disease have occurred in urban communities.² The prevalence of C. burnetii in milk ranges from 0% to as high as 95%.³ Individuals with vascular and heart valve disorders have a higher risk of serious complications. Doctors treat it with antibiotics like doxycycline and hydroxychloroquine, etc.

Why Is It Called Q Fever?

“Query fever” or “Q fever” was named so because in the 1930s and 1940s patients came to doctors with symptoms but the healthcare professionals had no clue about it Therefore, there were many questions and queries regarding the fever cause. Thus, it came to be known as query fever.

Q Fever Symptoms

Coxiella burnetii infection does not necessarily cause disease and most patients do not have any symptoms. When present, symptoms appear 3 to 30 days after exposure to the pathogen. The disease can present as an acute disease or a chronic infection. The chronic form has a higher mortality rate than the acute form i.e., 12-25% and 0.5-1.5%, respectively.
A wide variety of presentations make Q fever’s diagnosis even more challenging.

Acute Q Fever:

Fever & Chills

Raised body temperature is an evident symptom of microbial infections and Query fever is no exception. Fever, chills, and fatigue are commonly seen in patients suffering from the disorder.

Once inside, the infection can induce a process called hemophagocytosis in which the defense cells of the body (phagocytes) kill the blood cells. This contributes to raised temperatures of the body following C. burnetii infection.⁴

Sweating

The under-diagnosed disorder has a wide variety of presentations. Night sweats can perplex patients. A 55-year-old male developed fever/chills and night sweats following a motor vehicle accident and was diagnosed with Coxiella burnetii infection.⁵

Fatigue

Abnormal daily functioning and fatigue are known presentations. Acute Query fever can lead to long-term fatigue and have detrimental effects on your work productivity.⁶

Body Aches

Myalgias (muscle aches) and arthralgias (joint pains) by Q fever can hinder your day-to-day activities and reduce your quality of life.⁷

Headaches

Acute infection can cause severe headache. Several patients report pain in the retro-orbital area. Moreover, photophobia may also accompany headaches and myalgia.⁸

Skin Rash

Dermatological symptoms are not uncommon in C. burnetii infections. Many complain of having purple-colored skin rash. In a clinical study, a patient reported developing a nonpururitic (non-itchy) maculopapular reddish rash after infection.⁹

Respiratory Symptoms:

The bacterial infection can also have respiratory manifestations:

Cough

In addition to fever/chills, headache, and night sweats, patients also experience unexplained coughing.¹⁰

The radiographic image shows Q fever-induced pneumonia. Case courtesy of Yaïr Glick, Radiopaedia.org. From the case rID: 86858.

Chest Pain & Shortness of Breath

The development of serious symptoms like chest pain and shortness of breath can confuse doctors. Despite its contribution to heart muscle inflammation, Coxiella burnetii infection can mimic myocarditis as seen in a case with acute chest pain and extensive ST elevation.¹¹ Chest pain worsens with breathing. Many times the symptoms are indicative of pneumonia.

Gastric Disturbances:

GIT problems also make it to the list of the common Q fever symptoms.

Nausea & Vomiting

Studies of Q fever outbreaks reveal that nausea, vomiting, and diarrhea are associated with flu symptoms in numerous cases.¹²

Diarrhea

The bacterial infection can also upset your stomach and induce watery diarrhea.

Stomach Pain

There can also be abdominal pain along with symptoms of nausea, vomiting, and diarrhea. The abdominal pain is sometimes the result of underlying Q fever-induced hepatitis.¹³

Q Fever Fatigue Syndrome

In some cases, patients experience extreme fatigue for months (or even years) after exposure to the bacterial pathogen.

The condition is seen in around 20% of the cases and resembles chronic fatigue syndrome and is thus, called Q fever fatigue syndrome.¹⁴ Sufferers experience prolonged joint/muscle aches, night sweats, and headaches as well.

Chronic Q Fever:

The chronic type of the disease can have grave consequences as it usually affects the heart muscle, heart valves, and blood vessels. Here again, patients experience a wide array of symptoms, depending on the organs involved.

Fever

Unlike the acute form, the chronic type causes persistent low-grade fever.

Night Sweats

Sweating at night continues for a long period.

Weight Loss

Multiple complications caused by chronic Query fever lead to weight loss. Patients suffering from Q fever endocarditis report weight loss and anorexia.¹⁵ Moreover, patients with Q fever-related kidney disorders (glomerulonephritis) can also present with severe fatigue, decreased appetite, and weight loss.¹⁶

Fatigue

Reports suggest there is a high incidence of chronic fatigue in patients with chronic Q fever. According to a 6-year follow-up study, more than 60% of individuals were diagnosed with chronic fatigue syndrome after the European Q fever outbreak. Thus, persistent fatigue is an evident feature.¹⁷

Swelling Of Legs

As chronic Q fever tends to damage the kidneys and the heart, leg swelling can be seen in some long-term patients. A patient with rapidly deteriorating kidney function and leg swelling was diagnosed with Q fever.¹⁸

Breathing Difficulties

Chronic fever can lead to long-term trouble in breathing. Pleural pain and shortness of breath make life difficult.

Complications Of Q Fever

Serious complications are uncommon, and only 1 to 5% of people (who acquire C. burnetii infection) suffer from life-threatening ailments. Most of the patients have weak immunity or underlying serious health issues.

MRI shows vegetation in the mitral valve in a Q fever endocarditis patient. Image courtesy Lago-Rodriguez, A. E., Fraile-Ribot, P. A., Amengual-Antich, I., Gual-Capllonch, F., & Garcia-Gasalla, M. (2024). Q Fever Endocarditis: A Challenging Diagnosis in a Patient Referring Weight Loss and Anorexia, and With Granulomas in Gastric Biopsy Specimens. Clinical case reports, 12(12), e9635. https://doi.org/10.1002/ccr3.9635. Available via PubMed under CC.

Heart Issues:

Query fever-induced endocarditis is a major complication of the infection. It is mostly seen in patients suffering from heart valve issues or who have a history of endocarditis. Several heart conditions arise due to Coxiella infection.

Endocarditis

Q fever endocarditis refers to inflammation of the inner lining of the heart muscle. It is the most common cardiac manifestation of the disease and can prove to be fatal if left untreated.¹⁹

Myocarditis

Query fever myocarditis (inflammation of the heart muscle) is a rare yet severe manifestation of the disorder. However, it is usually associated with other comorbidities (like kidney failure). It has a poor prognosis if left untreated.²⁰

Other heart problems may include pericarditis, arotitis, etc.

Kidneys:

Query fever can harm the kidneys in several ways, which are discussed below:

Q Fever Glomerulonephritis

Inflammation of the kidney structures under bacteria action can lead to severe anemia and impaired renal function. Glomerulonephritis can lead to further complications and prove to be a life-threatening disease. Therefore, timely diagnosis and prompt treatment are crucial for the complete recovery of the patient.²¹

Acute Kidney Injury

Severe acute kidney injury can occur secondary to Coxiella burnetii infection. This can be life-threatening if left untreated.²²

Lungs:

Reports suggest that pulmonary involvement can be seen in both acute and chronic forms. Pulmonary complications may include pneumonia, lung consolidations, pleural effusions, and lymphadenopathy. Radiographic findings of such patients also suggest pulmonary edema.²³

Brain:

Inflammation from C. burnetii infection can spread to the brain and cause havoc. In rare instances, Query fever can cause the protective lining of the brain (meninges) to swell up and turn into a life-threatening disease.
Neurological conditions like aseptic meningitis and encephalitis are rare complications. However, these conditions demand immediate medical attention, and thus, quick diagnosis is the key to good treatment.²⁴
The atypical presentations of the fever (like meningitis and encephalitis) call for better diagnostic procedures like next-generation metagenomic sequencing.²⁵

Bones:

Rarely, it can lay the foundation for bone conditions like osteomyelitis. There have been some cases of Query fever-induced vertebral osteomyelitis that had been diagnosed very late.²⁶

Pregnancy:

C. burnetii infection in pregnant women can lead to complications like pregnancy failures²⁷ and miscarriages.

Q Fever Causes

What Causes Q Fever?

The bacterium Coxiella burnetii is the causative agent for the mysterious Query fever. The animal lives asymptotically in animals like cattle, sheep, and goats that carry the pathogen around. It is present in the following body fluids of the infected animals:

Urine
Stool
Milk
Amniotic fluid

Contact between the animal and the ground can transfer the bacteria into the soil. Humans become sick if they inhale the infected dust and mist particles.

Transmission & Spread

As already mentioned, the most common type of transfer to humans is via inhalation of contaminated dust/mist particles. Thus, most patients are individuals involved in dealing with livestock farming. Domesticated animals serve as the greatest source of infection for humans.²⁸
However, the stubborn pathogen of C. burnetii is capable of traveling some distance and infecting you without coming in contact with animals. Other ways of transmission include:

Tick bites
Blood transfusion
Mother-to-child transmission during pregnancy or childbirth
Consumption of unpasteurized dairy products like milk and cheese, et

Is Query Fever Contagious?

In most cases, the disease is not contagious. The pathogen may spread via the exchange of body fluids or physical contact. The only means of human-to-human transmission are mother-to-child (during pregnancy) and receiving blood from an infected person.

High Risk Groups

Certain groups of people are at a greater risk of developing severe forms of Q fever. The following people are at a higher risk of chronic Q fever (which is more severe than the acute form):

Pregnant women
Individuals with a history of valve disease or endocarditis²⁹
Kidney patients suffering from renal insufficiency
People who have vascular prostheses (prosthetic devices placed in vessels to keep them open)
Adults with weak immunity (transplant patients, HIV/Hepatitis patients, people taking immunosuppressant drugs)

Q Fever Diagnosis

Due to the diversity of symptoms and resemblance to other conditions, diagnosing Q fever is very tricky and may take a lot of time (with lots of trials and errors). However, the sequence of diagnosis will be as follows:

History & Physical Examination:

Your healthcare provider will ask about contact or working around animals. He will also inquire about medical history (history of heart valve disease, etc.) and the onset of symptoms. A question regarding a recent visit to a livestock farm may also help solve some questions.

Blood Samples:

If C. burnetii infection is suspected, a small sample of blood is taken and sent to the lab. Multiple tests can be performed at the lab:

Antigen Test

Lab experts use indirect fluorescent antibody (IFA) testing to check C. burnetii antigen in the blood. Multiple samples are taken (1st sample in the first week and 2nd sample 3-6 weeks later).

Antibody Test

Lab technicians detect antibodies (IgG) in the blood (which the body produces as a response to the pathogen). It also uses the IFA method.

PCR Test

Your healthcare provider may also order a Polymerase Chain Reaction (PCR) test to diagnose Q fever within the initial weeks of symptoms onset.

Bacterial Culture

The bacteria from the sample are grown in the lab and seen under a microscope for identification.

Differential Diagnosis:

Brucellosis Vs. Q Fever

Both brucellosis and Q fever are bacterial infections that share some similarities. Brucellosis is caused by Brucella, while Q fever arises due to Coxiella burnetii infection. While you may find fever, fatigue, and sweating in both conditions, the onset of Query fever is abrupt, while that of brucellosis is more gradual. One symptom that sets apart Q fever from brucellosis is headache.

Q Fever Treatment

The first line of treatment for Q fever is antibiotic therapy. Once diagnosed with it, your healthcare provider will prescribe a combination of antibiotics to treat the infection. Doxycycline is the most prevalent drug used to treat infection in adults and children. It is mostly combined with hydroxychloroquine.³⁰ Animal trials show the high efficacy of doxycycline and find levofloxacin as a potent alternative to doxycycline.³¹
Other efficacious drugs for Query fever include fluoroquinolones (like finafloxacin, ofloxacin, etc.),³² rifampin, clarithromycin, and Trimethoprim-sulfamethoxazole.
Your health professional may also prescribe anti-inflammatory and pain-killer drugs for symptomatic management of the disease.
Most patients respond well to antibiotics. However, only a small amount develops chronic unresolved symptoms that may last for months to years and are hard to cure.

Q Fever Prevention

You can adopt the following steps to keep the infirmity at bay:

Ask your healthcare provider for a Q fever vaccine if you are in a high-risk area. Currently, the vaccine is only available in Australia. However, it can be managed for other regions.
Wear protective gear (gloves and mask) when dealing with animal fluids.
Avoid consuming unpasteurized drinks/food items.
Get screened for heart valve problems to reduce the risk of infection.

Final Word

Q fever is a rare bacterial infection that has perplexed physicians. Coxiella burnetii is the causative agent that spreads to humans via inhalation of dust particles contaminated with it. In most cases, it has a milder acute form, but it may take a more serious chronic form. The infectious disease causes a wide variety of symptoms, including fever, headache, night sweats, skin rash, extreme fatigue, GIT, and respiratory symptoms. Weight loss and swelling of the legs are seen in chronic Q fever cases.
Farm animals like sheep and goats carry the pathogen in your body fluids (urine, amniotic fluid, milk, etc.). When the fluids mix in soil, they can get inhaled into the human body and cause infection. Diagnosis is difficult due to diverse symptoms but doctors treat the infection well with a combination of antibiotics like doxycycline and hydroxychloroquine, etc. You can prevent the disease by getting a vaccine, avoiding unpasteurized products, and wearing protective gear when dealing with livestock animals.

Refrences

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3
Pexara, A., Solomakos, N., & Govaris, A. (2018). Q fever and prevalence of Coxiella burnetii in milk. Trends in Food Science & Technology, 71, 65-72.
4
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5
Agostino, T., & Edwards, M. (2024). Q Fever, an Under-Recognized and Under-Diagnosed Disease: A Case Report. Cureus, 16(9), e70283.
6
Morroy, G., Keijmel, S. P., Delsing, C. E., Bleijenberg, G., Langendam, M., Timen, A., & Bleeker-Rovers, C. P. (2016). Fatigue following acute Q-fever: a systematic literature review. PloS one, 11(5), e0155884.
7
Honarmand, H. (2012). Q Fever: an old but still poorly understood disease. Interdisciplinary perspectives on infectious diseases, 2012(1), 131932.
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Miller, H. K., Priestley, R. A., & Kersh, G. J. (2021). Q fever: a troubling disease and a challenging diagnosis. Clinical microbiology newsletter, 43(13), 109-118.
9
Uribe Pulido, N., Escorcia García, C., Cabrera Orrego, R., Gutiérrez, L. A., & Agudelo, C. A. (2021, October). Acute Q fever with dermatologic manifestations, molecular diagnosis, and no seroconversion. In Open Forum Infectious Diseases (Vol. 8, No. 10, p. ofab458). US: Oxford University Press.
10
Asamoah, J. K. K., Jin, Z., & Sun, G. Q. (2021). Non-seasonal and seasonal relapse model for Q fever disease with comprehensive cost-effectiveness analysis. Results in Physics, 22, 103889.
11
Hammami, R., Bahloul, A., Charfeddine, S., Feki, W., Ayed, N. B., Abid, L., & Kammoun, S. (2021). Q fever presenting as myocarditis. IDCases, 23, e01056.
12
Tapia, T., Stenos, J., Flores, R., Duery, O., Iglesias, R., Olivares, M. F., … & Hormazabal, J. C. (2020). Evidence of Q fever and rickettsial disease in Chile. Tropical Medicine and Infectious Disease, 5(2), 99.
13
Mekonnen, G. (2020). Review on Q fever: epidemiology, public health importance, and preventive measures. Op Acc J Bio Sci Res, 6(4).
14
Raijmakers, R. P., Roerink, M. E., Jansen, A. F., Keijmel, S. P., Gacesa, R., Li, Y., … & Xu, C. J. (2020). Multi-omics examination of Q fever fatigue syndrome identifies similarities with chronic fatigue syndrome. Journal of translational medicine, 18, 1-13.
15
Lago‐Rodriguez, A. E., Fraile‐Ribot, P. A., Amengual‐Antich, I., Gual‐Capllonch, F., & Garcia‐Gasalla, M. (2024). Q Fever Endocarditis: A Challenging Diagnosis in a Patient Referring Weight Loss and Anorexia, and With Granulomas in Gastric Biopsy Specimens. Clinical Case Reports, 12(12), e9635.
16
Li, Y., Shen, Y., Yang, H., Li, M., Jiang, L., Ma, W., … & Su, T. Q Fever-Related Glomerulonephritis unveiled by Metagenomic Next-Generation.
17
Ankert, J., Frosinski, J., Weis, S., Boden, K., & Pletz, M. W. (2022). Incidence of chronic Q fever and chronic fatigue syndrome: A 6 year follow‐up of a large Q fever outbreak. Transboundary and emerging diseases, 69(4), 2219-2226.
18
Peng, M., Tang, B., Li, F., Deng, Y., Dai, Y., Chen, L., & Liu, W. (2023). A retrospective analysis of Q fever osteomyelitis in children, with recommendations. Microbes and Infection, 25(8), 105189.
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Million, M., Thuny, F., Richet, H., & Raoult, D. (2010). Long-term outcome of Q fever endocarditis: a 26-year personal survey. The Lancet Infectious Diseases, 10(8), 527-535.
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Goyal, A., Dalia, T., Bhyan, P., Farhoud, H., Shah, Z., & Vidic, A. (2022). A rare case of chronic Q fever myocarditis in end-stage heart failure patient: A case report. World Journal of Cardiology, 14(9), 508.
21
Loyen, M., Wiech, T., Reuter, S., & Thölking, G. (2024). Case report: membranoproliferative glomerulonephritis associated with Q fever causing chronic endocarditis. BMC nephrology, 25(1), 291.
22
Stewart, A. G., Broom, J., Sowden, D., & Hollett, P. (2019). Acute kidney injury in acute Q fever. Internal Medicine Journal, 49(10), 1326-1329.
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29
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Why Is It Called Q Fever?

Q Fever Symptoms

Acute Q Fever:

Fever & Chills

Sweating

Fatigue

Body Aches

Headaches

Skin Rash

Respiratory Symptoms:

Cough

Chest Pain & Shortness of Breath

Gastric Disturbances:

Nausea & Vomiting

Diarrhea

Stomach Pain

Q Fever Fatigue Syndrome

Chronic Q Fever:

Fever

Night Sweats

Weight Loss

Fatigue

Swelling Of Legs

Breathing Difficulties

Complications Of Q Fever

Heart Issues:

Endocarditis

Myocarditis

Kidneys:

Q Fever Glomerulonephritis

Acute Kidney Injury

Lungs:

Brain:

Bones:

Pregnancy:

Q Fever Causes

What Causes Q Fever?

Transmission & Spread

Is Query Fever Contagious?

High Risk Groups

Q Fever Diagnosis

History & Physical Examination:

Blood Samples:

Antigen Test

Antibody Test

PCR Test

Bacterial Culture

Differential Diagnosis:

Brucellosis Vs. Q Fever

Q Fever Treatment

Q Fever Prevention

Final Word

Refrences

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