TY - CHAP M1 - Book, Section TI - Q Fever A1 - Cherry, Cara A1 - Kersh, Gilbert J. A2 - Boulton, Matthew L. A2 - Wallace, Robert B. PY - 2022 T2 - Maxcy-Rosenau-Last Public Health & Preventive Medicine, 16e AB - Q fever in humans is caused by infection with the gram-negative bacterium Coxiella burnetii. The organism grows intracellularly in a parasitophorous vacuole at acidic pH (4.75).1C. burnetii is a member of the gammaproteobacteria and is classified in the order Legionellales, family Coxiellaceae. This bacterium infects a broad range of animal species, and is thought to be transmitted primarily by inhalation, but tick transmission could play a role in maintaining the bacteria in wildlife. Q fever is a zoonosis, and humans usually acquire the disease via inhalation of contaminated dust or dried material from animal waste, with a small number of organisms (<10) thought to be able to initiate an infection.2 Infected livestock, such as cattle, sheep, and goats are the primary reservoirs for human exposure. The organism can grow to very high densities in the placenta of infected livestock. Therefore, these animals shed the largest amounts of C. burnetii during parturition. The replicative form of C. burnetii has been described as the “large cell variant” (LCV), whereas nonreplicating C. burnetii will form a spore-like “small cell variant” (SCV).3 The SCV is resistant to heat and desiccation resulting in impressive stability in the environment.4 The environmental stability, transmission by inhalation, and low infectious dose have led to classification of C. burnetii as a potential bioweapon and inclusion on the list of select agents maintained by the U.S. Department of Health and Human Services. SN - PB - McGraw Hill CY - New York, NY Y2 - 2024/03/29 UR - accessmedicine.mhmedical.com/content.aspx?aid=1182667428 ER -