Legionella and Q fever community acquired pneumonia in children.

Abstract

Q (for query) fever is a worldwide zoonosis. The disease was first described in 1937 by Derrick, a public health official in Queensland, Australia, while investigating an outbreak of an unknown febrile illness among abattoir workers. McFarlane-Burnet and Freeman isolated a Gram-negative intracellular bacterium from a mouse infected with material sent from Derrick. At the same time Davis and Cox at the Rocky Mountain Laboratory in Montana isolated an organism from ticks collected near Nine Mile Creek. In 1938 it was found that the Nine Mile agent and the Q fever agent were identical. The agent was named Coxiella burnetii to honor Cox and Burnet. Since then, C. burnetii has been isolated from several animal species. Farm animals and pets are the main reservoirs of infection for humans. Humans acquire the infection mainly via inhalation of infected aerosolised particles or ingestion of unpasteurised dairy products. Q fever manifests with a wide spectrum of clinical syndromes. Following primary infection with C. burnetii, half of the patients remain asymptomatic. Among those who are symptomatic, acute Q fever most frequently manifests as a self-limited febrile illness, pneumonia or hepatitis. Endocarditis is the predominant form of chronic Q fever. Despite the availability of well-established epidemiological associations and reliable serologic tests (immunofluorescence assay is the reference method), Q fever is infrequently diagnosed in the clinical setting.1 The current review summarises Q fever pneumonia in children, with emphasis on its laboratory diagnosis.