Abstract |
Q fever is a zoonosis with a worldwide distribution caused by Coxiella burnetii, an obligatory intracellular Gram-negative bacterium. It is characterized by high infectivity and is classified as a class B bioterrorism agent.
The main hosts of the bacterium are animals of veterinary importance such as cattle, goats and sheep but it can also be found in other domestic mammals, birds and ticks. Coxiella burnetii is excreted in urine, faeces and milk of infected animals, however, higher concentrations of pathogen are detected in the birthing products.
The disease is transmitted mainly through inhalation of infected droplets. Infection remains asymptomatic in animals, although reported recurrent miscarriages in infected animals have been reported, which permit continuous shedding of bacteria in the environment. In humans, Q fever can occur in an acute or a chronic form.
The acute form of the disease usually appears as a self-limited febrile illness with upper respiratory infection symptoms, but can cause more serious clinical manifestations such as pneumonia, hepatitis and CNS infections.
The most common manifestation of the chronic form of the disease is endocarditis that usually occurs in patients with underlying valvular disease.
Particular attention is needed during pregnancy because of the potential for serious complications. Treatment depends on the shape and characteristics of the infection. It is particularly difficult in children and in women who are pregnant, because of contraindication of administration of various antibiotics, and in cases demanding long-term treatment.
Vaccines are available but their use is limited.
Following acute Q fever infection, monitoring by serological tests and ultrasound is recommended in order to early detect cases of transition to chronic Q fever (mainly in the form of endocarditis).
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