Q fever

"The 21 August 1937 issue of the Medical Journal of Australia contained two articles on a hitherto unknown disease affecting abattoir workers and farmers — Q fever (with the “Q” standing for query). The first of these was by Edward Holbrook Derrick, Director of the Laboratory of Microbiology and Pathology, Queensland Health Department, Brisbane, and comprised his meticulous clinical descriptions and subsequent experiments to isolate the causative organism. ... During his research, Derrick sought the help of Frank Macfarlane Burnet, and the second article by Burnet and Mavis Freeman from the Walter and Eliza Hall Institute of Medical Research in Melbourne described their identification of the causative agent."

"Quantitative estimation of an individual's risk of infection due to airborne pathogens requires knowledge of the pathogen's infectious dose, in addition to estimates of the pathogen's airborne concentration and the person's exposure duration. Based on our review of the published literature on Q fever, we conclude that the infectious dose of Coxiella burnetii is likely one rickettsia, and that the probability of a single organism initiating infection is approximately 0.9. Findings in experiments exposing guinea pigs to C. burnetii via intraperitoneal injection and inhalation of respirable aerosols firmly support a “one-hit” Poisson model of infection."

"The cows were heavily infected with rickettsiae, and we were getting cases of Q fever in people who were drinkers of raw milk, and in dairy workers who were surrounded by a contaminated atmosphere. We mentioned how artificial dairy husbandry is down there in the Los Angeles area. You've got these enclosure where the cattle are kept, and of course, as manure accumulates, the cattle get higher and higher off the ground, to the point they can probably step over the fence. At that time, the dairy people bring in bulldozers and clean out the premises, and that's when you begin to get a few cases of Q fever, either amongst the employees or amongst the neighbors."

"This disease typically manifests as a self-limiting, febrile illness known as acute Q fever. Due to the aerosol transmissibility, environmental persistence, and infectivity of C. burnetii, this pathogen is a notable bioterrorism threat."