For personal use. Only reproduce with permission from The Lancet Publishing Group. THE LANCET Infectious Diseases Vol 2 November 2002 http://infection.thelancet.com 686 Review Q fever in children Q fever in children Helen C Maltezou and Didier Raoult Q fever is a zoonosis caused by Coxiella burnetii. Farm animals and pets are the main reservoirs of infection, and transmission to human beings is mainly accomplished through inhalation of contaminated aerosols. This illness is associated with a wide clinical spectrum, from asymptomatic or mildly symptomatic seroconversion to fatal disease. Q fever in children has been rarely reported. We reviewed published work on this topic. Seroepidemiological studies show that children are frequently exposed to C burnetii. However, children are less frequently symptomatic than adults following infection, and may have milder diseases. Using the standard diagnostic criteria, we identified 46 published paediatric cases only. Self-limited febrile illness and pneumonia were the most common manifestations of acute Q fever. Chronic disease manifested as endocarditis and osteomyelitis. A history of exposure to possible sources of infection with C burnetii in a child with a compatible infectious syndrome should prompt testing for Q fever. Studies are required to determine the spectrum of morbidity associated with Q fever during childhood. Lancet Infect Dis 2002; 2: 686–91 Q (for query) fever was first described in 1935 by E Derrick, a public health official in Queensland, Australia, while investigating an outbreak of an unknown febrile illness among abattoir workers. Q fever is a worldwide zoonosis caused by the obligate intracellular bacterium Coxiella burnetii (figure 1). In most cases this illness has a self- limiting febrile course, but it may also manifest with a variety of non-specific symptoms that are commonly encountered in many other illnesses. Thus, as with other rickettsioses, Q fever is infrequently suspected and remains unrecognised. During the last decade our knowledge on Q fever has greatly expanded, mainly due to the identification of new clinical manifestations, the recognition of the role of host factors in the expression of acute Q fever and evolution to chronic infection, and the adoption of prolonged combination antibiotic regimens for Q fever endocarditis. 1,2 However, the overwhelming body of published information focuses on adults disease. Q fever in children has been scantily presented in the literature and may remained under-diagnosed. Q fever has been historically considered an occupational hazard among professionals in contact with farm animals or their products. However, there are an increasing number of cases among people with an urban life style following occasional contact with farm animals or with dogs and cats. 1 We have tested more than 100 000 sera for Q fever in our centre since 1985. The purpose of this article is to review with strict diagnostic criteria the current state of knowledge on Q fever in children. Use of consistent laboratory criteria permits reliable comparison of clinical manifestations of Q fever among different areas and populations. Epidemiological sources of Q fever Due to its spore-like form C burnetii may remain viable in soil and milk for several months following contamination. 3 Cattle, sheep, and goats are the main reservoirs of C burnetii infection for humans (figure 2). High densities of C burnetii are found in the placenta of infected parturient animals and are shed in the environment following labour. Human beings are infected mainly via inhalation of contaminated aerosols. 1,4–6 In Europe most cases occur between January and June because of the heavily contaminated environment following lambing season. 1,4,7 Cases among students following visits to farms as part of school activities, and outbreaks following exposure to birth products of cats, dogs, and rabbits have been reported. 1,3,8–11 C burnetii may also be transmitted by ingestion of unpasteurised dairy products. 12,13 Human cases have been reported following contact with parturient products of an infected woman (in HCM and RR are at the Unité des Rickettsies, Faculté de Médecine, Université de la Méditerranée, Marseille, France Correspondence: Professor Didier Raoult, Unité des Rickettsies, Faculté de Médicine, Université de la Méditerranée, CNRS UMR 6020, IFR 48, 27 Boulevard Jean Moulin, 13385 Marseille Cedex 05, France. Tel +33 4 91 32 43 75; fax +33 4 91 32 03 90; email Didier.Raoult@medecine.univ-mrs.fr Figure 1. C burnetii, the agent of Q fever (arrow), surviving and multiplying in a human macrophage (electronic micrograph).