What is Q Fever?

Q fever is a type of illness that causes fever, is spread between animals and humans, and is found throughout the world. It was first discovered in Queensland, Australia, in 1935 among people who work with meat. Because the cause couldn’t be found initially, it was called “Q (query) fever.” This disease usually affects livestock and the farm workers who deal with animals like cows, goats, and sheep.

Most often, people with Q fever will experience a fever that goes away on its own. However, there can be severe symptoms in some cases. In the United States, cases of Q fever have to be reported, and its cause, a bacterium called C. burnetii, is considered as a potential agent for bio-weapon .

What Causes Q Fever?

The bacteria responsible for a disease known as Q fever is called Coxiella burnetii. This is a kind of bacteria that can change shape and lives inside cells. It’s closely related to another type of bacteria, Legionella. Coxiella burnetii can withstand the acidic environment inside host cells, which is crucial for its survival.

Fascinatingly, it can turn itself into a form similar to a spore, which helps it survive outside in harsh conditions for long periods of time. This bacteria also has the ability to change itself in two different ways, according to the changes in the environment around it.

The first type of change is called a virulent phase, which allows the bacteria to become more harmful or aggressive, especially in lab animals and in the natural environment. This type of change tends to delay the body’s immune response. The second type of change happens when the bacteria turn into a non-harmful or avirulent phase, by altering its outer covering, usually seen when the bacteria is grown in lab settings over several generations.

Risk Factors and Frequency for Q Fever

Q fever is a disease that, despite being notifiable since 1999 in the United States due to its potential as a bioweapon, remains underreported and not well-known. It tends to affect men more than women, with a ratio of 3 to 1. The positive seroprevalence rate, or the percentage of the population that tests positive for the disease, is 3.1%. It is found more commonly in males, the elderly, Hispanics, and those in impoverished situations. The disease can be carried by various pests like ticks, and infects both domestic and wild animals. This infection can occur via bites or through the pests’ waste contaminating the skin of the host.

Common carriers of Q fever include domestic animals like cattle, sheep, and goats, as well as horses, dogs, and swine.
Wild animals, including birds, squirrels, mice, rats, cats, and rabbits can also carry the disease.
While Q fever can occur at any time of the year, most cases occur in the spring and early summer, during the birthing season for cattle, sheep, and goats.
Through the urine, feces, milk, and placenta of infected animals, people can be exposed to a high concentration of the bacteria that causes Q fever. This means that those who handle contaminated items, consume contaminated raw milk, or have exposure to the placenta of infected animals are at risk.
Workers who directly interact with infected animals, like farmers, veterinarians, and slaughterhouse employees, are also at risk for Q fever
The disease can also spread via contaminated materials like manure, straw, and dust from farm vehicles, as well as through things like blood transfusions, autopsies, clinical care, infected hardware removal, and raw milk consumption.
In recent years, Q fever outbreaks in European cities have been linked to sheep and goat farming in urban areas.
HIV-positive individuals and others with compromised immune systems are at a higher risk for severe symptoms of Q fever.

Signs and Symptoms of Q Fever

Q fever is a condition that can present in different ways depending on a person’s age, immune system, and location. While the acute form of Q fever is more prevalent and affects the body as a whole, the chronic version only shows up in fewer than 5% of cases and tends to focus on a specific organ system.

Acute Q Fever

The usual symptoms of acute Q fever are high-grade fevers, headache, fatigue, and muscle pain, which might last 1 to 3 weeks. The illness typically begins abruptly, approximately 20 days after exposure. Headaches are often accompanied by sensitivity to light. Pneumonia is another common symptom, especially in the elderly, and is often associated with other symptoms such as chills, sweats, muscle pain, chest pain, nausea, vomiting, and diarrhea. Pleural effusion, or excess fluid around the lungs, may also occur. Symptoms typically last from 10 to 90 days.

Rash is a common symptom seen in children, while younger adults often experience Acute hepatitis which can lead to yellowing of the skin and eyes, or Cholestatic jaundice. Neurological complications have also been reported, and a small number of patients may develop acute endocarditis, an inflammation of the heart valves.

High-grade fevers
Headache
Fatigue
Muscle pain
Pneumonia
Chills
Sweats
Chest pain
Nausea
Vomiting
Diarrhea
Rashes (in children)
Hepatitis (in younger adults)
Neurological complications
Acute endocarditis (in rare cases)

Chronic Q Fever

Only 1 to 5 percent of people infected with the Q fever bacteria develop chronic Q fever. The most common symptoms of chronic Q fever are infective endocarditis, or infection of the heart valves, infection of vascular prosthetics and existing aneurysms, and rarely, bone infection or interstitial lung fibrosis. People with pre-existing heart abnormalities are more likely to get infective endocarditis. Residual neurologic symptoms can include weakness, recurrent headache, blurred vision, sensory loss, and tingling or numbness.

Q Fever in Pregnant Patients

While pregnant patients are typically symptom-free, Q fever can lead to complications such as spontaneous abortion, low amniotic fluid, slowed fetal growth, fetal death, and preterm birth.

Post-Q Fever Fatigue Syndrome

About 20% of patients develop post-Q fever fatigue syndrome after an episode of acute Q fever. Symptoms include severe tiredness, nausea, headache, night sweats, muscle and joint pain, swollen lymph nodes, decreased focus, depression, sleep issues, and short-term memory loss. This can occur in patients whose symptoms resolved on their own and those who were treated with antibiotics. Interestingly, its occurrence seems to vary by geographical location.

Testing for Q Fever

Acute Q fever is a condition that can influence a range of blood cell counts in your body. The number of white blood cells could be normal or high, and the number of platelets, which are critical for clotting, might also fluctuate. Elevated liver enzymes are a common finding; however, the bilirubin (a substance found in bile) level in your blood might not change.

Examining your cerebrospinal fluid, or CSF (fluid surrounding your brain and spinal cord), might indicate more of certain types of cells (mononuclear pleocytosis) and higher-than-normal protein levels. A chest x-ray might reveal multiple hazy, rounded areas, whether situated in specific lung segments or not, or near the pleura (the thin tissue layer covering the lungs and inside the chest cavity), as well as swollen lymph glands near the lungs (hilar adenopathy).

An echocardiogram, a type of ultrasound that visualizes heart structures, might show vegetations or abnormal growths, especially in chronic Q fever cases, but these might be evident only in about half of such cases.

The diagnosis of Q fever is typically confirmed by blood tests or a test called Polymerase Chain Reaction (PCR), which detects the presence of the causative organism’s genetic material in the blood. High levels of caution are required when handling tissue samples from Q fever patients due to their potential to spread infection, warranting safety measures usually reserved for extremely dangerous pathogens (biosafety level 3).

A special type of blood test, called an indirect immunofluorescent test, is generally preferred to diagnose both acute and chronic Q fever. It looks for two types of antibodies (the body’s defense mechanism against foreign material), specifically Anti phase I and II IgG antibodies.

In the early stage of Q fever, the Anti phase II IgG antibodies typically show up in higher quantities. A notable increase in these Anti phase II antibodies between initial illness and recovery provides confirmation for acute Q fever.

PCR testing is particularly useful when acute infection is suspected, but blood test results are inconsistent. It could also aid in confirming diagnoses in patients showing persistent high levels of Anti phase I antibodies suggestive of heart valve or blood vessel infections. This test could be performed on a range of samples, including blood, cerebrospinal fluid, pleural fluid, heart valve tissue, as well as samples from various other body sites and fluids. Optimal results are obtained if the sample is taken within two weeks of symptoms appearing, either before or immediately after the first antibiotic dose (within 24-48 hours).

But remember, the presence of Q fever DNA in an epidemic situation does not necessarily mean that you have the disease. Techniques such as magnetic resonance imaging and computed tomography can also assist in the diagnosis. In specific cases, positron emission tomography combined with computed tomography can be helpful in diagnosing Q fever infections in artificial joints and heart valve infections.

Treatment Options for Q Fever

The most effective way to treat acute Q fever is with the antibiotic doxycycline. However, if someone is not able to take doxycycline or if it doesn’t work for them, other antibiotics like minocycline, trimethoprim-sulfamethoxazole, or clarithromycin can be used.

In pregnant women acute Q fever that isn’t life-threatening should be treated with trimethoprim-sulfamethoxazole up until the 32nd week of pregnancy. This is done despite the fact that this drug is a “pregnancy category C” drug, which means it could potentially have negative effects on the baby. Nevertheless, it’s used because the risks to the baby from untreated Q fever, like miscarriage or stillbirth, are even higher. In addition, the medication could also result in slower growth of the baby and earlier delivery. To reduce the chances of birth defects, folic acid should also be given. If the Q fever infection threatens the life of the mother or if they cannot tolerate trimethoprim-sulfamethoxazole, doxycycline should be used. It is also advised to monitor the levels of Q fever in the blood at different times after the baby is born, as well as during any future pregnancies.

In cases where pregnant patients have persistent, localized infections, trimethoprim-sulfamethoxazole is used. For chronic Q fever during pregnancy, a combination of doxycycline and hydroxychloroquine are prescribed and should be taken for one year after the baby is born. And for Q fever endocarditis (a heart infection), a combination treatment of doxycycline and hydroxychloroquine is given for 18 to 24 months, depending on the type of valve involved in the heart infection. If the levels of Q fever in your blood decrease four times, it means the treatment has been completed. But if someone cannot take hydroxychloroquine, they can replace it with either ciprofloxacin or rifampin. Any artificial valves involved in the heart infection must be replaced surgically. Unfortunately, antibiotics are not effective for the extreme tiredness that can follow Q fever, also known as Q fever fatigue syndrome.

A vaccine for Q fever exists and is given to high-risk individuals in Australia, but it’s currently not recommended in the United States.

People with short-term viral infections, like the Epstein-Barr virus, cytomegalovirus, flu, or hepatitis A, B, or C, often have similar symptoms. These might include fever, liver inflammation, and muscle pain. These infections can be identified with blood tests and PCR tests. Atypical pneumonia, which can be caused by bacteria like Legionella and Mycoplasma, should also be considered. These can be ruled out by testing for a specific protein in the urine or antibodies in the blood.

Tick-borne diseases like Lyme disease, relapsing fever, and Rocky Mountain spotted fever typically cause fever and headache, sometimes accompanied by a rash. Other diseases carried by ticks, such as Anaplasmosis and Ehrlichiosis, usually present with fever, headache and liver inflammation, with a rash being less common. These diseases can be detected with PCR tests or blood tests.

Zoonotic diseases – diseases that can pass from animals to humans – such as brucellosis and leptospirosis, can also look like a severe flu. These often happen in people who have been exposed to animals or animal products.

What to expect with Q Fever

When promptly diagnosed and treated, acute Q fever, a type of infection caused by bacteria, generally has a very good chance of recovery. However, individuals who already have heart valve disease and pregnant women with acute Q fever face a higher risk of getting endocarditis, a serious infection of the inner lining of the heart chambers and valves.

To reduce this risk, medical professionals recommend regularly checking blood tests and conducting an imaging test called an echocardiogram, especially when the blood tests show high levels of antibodies against the bacteria.

Treatment in pregnant women often leads to better outcomes if administered promptly. For those who develop endocarditis, the chances of recovery are higher when two types of treatments are combined compared to using only one type of treatment.

Possible Complications When Diagnosed with Q Fever

Acute Q fever has the potential to cause severe health issues, such as fatal pneumonia affecting the spaces between lung tissues, inflammation of the heart muscle or its protective lining, inflammation of the brain or the lining of the brain, and gallbladder inflammation. People with a compromised immune system are more likely to experience these complications. If Q fever continues for a long time, it can lead to infections in artificial blood vessels and artificial heart valves. If left untreated, inflammation of the inner layer of the heart can cause serious heart-related problems. Chronic Q fever can also cause persistent fatigue syndrome, destroying red blood cells leading to a condition known as hemolytic anemia and causing bone marrow tissue to die. If pregnant women who have Q fever do not receive treatment, it could result in poor outcomes for their babies, including miscarriage.

Potential Complications:

Fatal interstitial pneumonia (fatal lung tissue disease)
Myopericarditis (inflammation of heart muscle or its lining)
Aseptic meningitis (brain lining inflammation)
Encephalitis (brain inflammation)
Cholecystitis (gallbladder inflammation)
Vascular prosthesis infection (infecting artificial blood vessel)
Prosthetic valve infections (infecting artificial heart valves)
Serious cardiac complications if endocarditis is not treated
Q fever fatigue syndrome
Hemolytic anemia (destruction of red blood cells)
Bone marrow necrosis (death of bone marrow tissue)
Poor fetal outcomes, including abortion, for untreated pregnant women with Q fever

Preventing Q Fever

People should be encouraged to drink pasteurized milk and eat food products made from it. The community should also be given guidance on how to correctly get rid of products that come from infected animals. Workers who handle hoofed animals and the products these animals produce on farms and in other livestock environments need to be educated about where infections can come from and how to prevent them.