Q Fever (Coxiella Burnetii)

Abstract

Q fever is a zoonotic infectious disease caused by the Coxiella burnetii bacterium. It is an obligate intracellular pathogen with a high infection capacity that proliferates exclusively in an acidified medium, forming a lysosome-like vacuole. It presents a peculiar phenomenon called "antigenic phase variation," produced by a modification in the complexity of the membrane lipopolysaccharides. Q fever can be found worldwide and presents variable clinical features and geographical distribution. It mostly affects people in rural areas who are in contact with animals. The most common type of transmission to humans is via the inhalation of aerosols containing the pathogen, especially those formed from placental derivatives. Wild animals, domestic animals, and ticks are the principal reservoirs.Diagnosis is mainly made by indirect methods such as serology or by direct methods such as microbiological cultures or tests that detect the specific DNA. Typically, there are two clinical presentations: the acute disease, which is more frequent and often asymptomatic, and a persistent focalized infection in 4 to 5% of patients, generally with a poor evolution. Treatment of the acute form in both children and adults consists of administering doxycycline, while persistent focalized infection should be treated with at least two antibiotics, such as doxycycline and hydroxychloroquine. Several measures should be undertaken to minimize exposure among people working with animals or handling birth products. Different vaccines have been developed to prevent infection, though few data are available.