Q Fever

Q fever is a disease caused by a bacterial infection. It is found in all areas of the world except for New Zealand and was first identified in Australia in 1935. When the disease was first discovered, its cause was unknown and, as such, it was termed ‘Q fever’, with ‘Q’ relating to the term ‘query’.

Humans are very susceptible to Q fever, with a small number of bacteria required to infect a patient. Although all persons are susceptible to Q fever, those working with animals and those processing animal products are at a higher risk of becoming infected (e.g., veterinarians, meat processing plant workers, sheep and dairy workers, livestock farmers, and researchers at facilities housing sheep and goats). 

For people who are pregnant, the disease symptoms can be more severe and can include complications in pregnancy, miscarriage and stillbirth. A woman infected with Q fever during her pregnancy is also more susceptible to developing chronic Q fever.

Persons with heart disease, blood vessel abnormalities and a suppressed immune system are also more susceptible to developing chronic Q fever.

The bacteria are resistant to heat, drying and many disinfectants. Therefore, the bacteria can survive for extended periods of time in their environment.

The symptoms of Q fever, and their severity, vary widely with some infected individuals experiencing no symptoms at all. Symptoms can mirror those of the flu and include fever, chills, cough, fatigue, muscle pain, headache, nausea, vomiting, diarrhoea, chest pain, stomach pain and weight loss. More severe symptoms could include pneumonia and hepatitis.

In approximately 20% of Q fever cases, the patient’s symptoms may reoccur; this is called post-Q fever fatigue syndrome. Symptoms include constant fatigue, sweating at night, headaches, sensitivity to light, muscle aches/pains, changes to mood and/or sleep disturbances.

In rare and severe cases (less than 5% of infected people), infected individuals may experience a more severe and long-lasting infection, termed chronic Q fever. The most common symptom of chronic Q fever is inflammation of the inner heart and heart valves (endocarditis). Many months of antibiotic treatment are required to treat chronic Q fever. The condition can be fatal if not treated.

Q fever is difficult to diagnose because the symptoms are common to a wide variety of diseases. Since Q fever is diagnosed by a blood test, treatment may be advised before the blood test results are returned to the physician. Antibiotic treatment is most effective if begun within the first 3 days of symptoms appearing.

Many patients will recover without antibiotics, however, doxycycline is the recommended antibiotic for the treatment of more severe cases of Q fever (for non-pregnant patients). Chronic Q fever is treated with many months of antibiotic treatment (usually doxycycline and hydroxychloroquine).

Q fever occurs worldwide, except in New Zealand. Since Q fever is spread to humans from infected animals, Q fever can be found wherever there are infected animals. Nevertheless, contact with the infected animal is not required as the bacteria can be carried over long distances in the wind.

The highest rates of Q fever are observed during the spring, the animal birthing season.