Posted August 20, 2022 by Anusha ‐ 5 min read
Q fever is a zoonotic disease that is transmitted from animals to humans. It is caused by the bacterium Coxiella burnetii which is mainly found in cattle, sheep, and goats. The bacteria is present in the milk, urine and feces of the infected animals. Moreover, large numbers of bacteria are shed in the birth products like placenta and amniotic fluid during birthing. When these products dry over time they contaminate the air. Inhalation of this contaminated air can cause infection in humans.
Q fever is caused by the bacterium
It is primarily found in cattle, sheep and goats.
The bacteria pass into milk, urine and feces of infected herd animals.
Infected aerosols can also travel, affecting people living downwind of an infected goat or sheep farm.
Other causes include contact with contaminated clothing, wool, hides or straw, dressing infected animals or consuming infected raw or unpasteurized dairy products.
Usually, Q fever is an occupational disease seen in slaughterhouse and dairy workers, livestock farmers, rendering-plant workers, herders, woolsorters, veterinarians or those involved in animal studies or research.
The bacterium is highly infectious in nature and remains viable in dust and stool for months. Even a quick exposure to the bacterium can cause an infection.
However, person-to-person spread is extremely unlikely. Very rarely, Q fever can spread through blood transfusion, from a pregnant woman to her fetus, through sexual intercourse or by the bite of an infected tick.
The infection can cause two types of Q fever that vary by severity and nature. The two types are:
Acute Q fever
This form of Q fever usually begins two to three weeks after exposure to the bacterium. Acute Q fever is characterized by flu-like symptoms which include high fevers, chills, muscle pain, and headaches. Acute Q fever is usually self-limited which means it can resolve itself without treatment.
Chronic Q fever
This form of Q fever may occur months to years after acute disease or without a previous history of acute Q fever. It has been observed that predisposing conditions such as pre-existing heart valve or vascular abnormalities or an immunocompromised immune system increases the risk for chronic Q fever.
Signs and symptoms include:
High fever (upto 105°F)
Malaise or general feeling of being unwell
Chills or sweats
Shortness of breath
Chest pain while breathing
Drowsiness or confusion
Sensitivity to light
The following are at high risk as they are exposed to animals and animal products:
Workers in cattle, sheep, and goat abattoirs
Farmers, stockyard workers, and livestock transporters
Wool shearers and sorters
Agricultural college staff and students
Wildlife and zoo workers exposed to high-risk animals
Veterinarians, veterinary nurses, and students
Tanning and hide workers
Professional dog and cat breeders
Laboratory workers handling veterinary products or working with Coxiella burnetii
Others who are exposed to cattle, camels, sheep and goats or their products
If you are located close to a farm or farming facility or live on a farm that may increase your risk towards the disease.
Though there is no specific time of year when one can get infected, it seems to be more common in the spring and early summer.
Consumption of unpasteurized milk or dairy products
Not often, but rare cases were reported by consuming infected raw, unpasteurized milk or dairy products.
A weak immune system can increase the risk for a severe form of the infection. Some of the common reasons that lead to weakening of the immune system include:
Certain diseases such as acquired immunodeficiency syndrome (AIDS) and cancer
Excessive consumption of medicines such as steroids, anti-cancer drugs, and painkillers
Lifestyle habits such as smoking, excessive drinking, and unhealthy eating
Individuals infected with Q-fever develop specific antibodies against Q fever including immunoglobulin G (IgG), immunoglobulin A (IgA) and immunoglobulin M (IgM). Measuring the levels of these classes of antibodies can help confirm a diagnosis of Q fever.
During the acute phase of Q fever, IgG and IgM antibodies may be detected. In chronic Q fever, IgG or IgA levels may be detected.
The most common serological tests for Q fever that detects the presence of specific antibodies or antigens in the blood or other fluids are:
Enzyme-linked immunosorbent assay (ELISA)
Polymerase chain reaction (PCR) test
A PCR test is a highly sensitive test to detect the presence of C. burnetii infection in biopsy specimen. It can detect infection earlier than the antibody test, but it is less readily available. However, a negative PCR result does not rule out the diagnosis.
Complete blood count (CBC)
It is done to check for low red blood cells (anemia) and levels of white blood cells.
Liver function or kidney function tests
They are done to diagnose any liver or kidney malfunction.
Doxycycline is the most commonly prescribed antibiotic for treating Q fever. People with chronic Q fever usually are prescribed a combination of antibiotics for a span of 18 months. Once the chronic Q fever is treated, your doctor may ask you to come back for follow up tests to confirm the absence of recurrence.
Some individuals might not respond to the antibiotic treatment, in that case, the doctor will prescribe some anti-inflammatory drugs. Hydroxychloroquine, a drug used for treating malaria, has been found to be effective against Q fever.
If you are pregnant and show symptoms of the disease, your doctor will recommend an antibiotic treatment. The medication type may vary depending on your condition.
Chronic Q fever, the severe form of the infection, can be difficult to treat. Endocarditis, inflammation of the inner lining of the heart’s chambers and valves, may require the patient to undergo multiple drug treatments. People with heart conditions require an early diagnosis and antibiotic treatment for at least 18 months.