In late October 2000, a general practitioner reported to the Drôme Public Health Inspector three cases of acute infectious syndromes that had occurred within a 10-day period in the same small rural town, suggesting a diagnosis of Q fever, a rickettsial disease caused by Coxiella burnetii. After biological confirmation of the diagnosis, an active case-finding effort was conducted, confirming the occurrence of a cluster of Q fever cases in this town. An epidemiological investigation was initiated by the DDASS and the CIRE Rhône-Alpes-Auvergne to identify the probable source of contamination, specifically to test the hypothesis of airborne transmission from one or more livestock farms identified by the exploratory investigation. Control subjects were recruited by random selection from the municipality’s voter registry and were tested using indirect immunofluorescence (IFI) to exclude immune individuals. At the same time, the Drôme Departmental Directorate of Veterinary Services implemented inspections of livestock farms in the municipality. Ten cases occurred between October 4 and December 10, 2000. These were adults living or working in the municipality of Montoison. Of the 50 controls tested, three tested positive for Q fever and were excluded from the analysis. The results of the case-control study revealed a significant association between traveling at least once a day on the Montoison-Crest departmental road (north/southeast axis) and the onset of the disease (OR=9.1 [1.62-51.12]), as well as an association between traveling on foot or in an open vehicle (bicycle, tractor) on a local road south of the village and the onset of the disease (OR=11.5 [0.93–142.23]). A comparison between cases and controls of the distances in kilometers from their homes to three farms located in the southern part of the municipality also shows a difference between cases and controls, with a statistical test close to the 5% significance threshold for two of these three farms (Mann-Whitney test). The veterinary investigation confirms the high prevalence of positive serology results in samples from animals tested at farms 2 and 3 (80% and 66% of positive serology results confirmed by IFI, respectively). Furthermore, manure from these two farms was spread in the southern part of the municipality during periods that may correspond to the periods of contamination of the cases. Following the results of these investigations, the veterinary services department implemented control measures regarding these farms: medical treatment of the animals, pasteurization of milk, covering of manure, and a ban on manure spreading. However, since these measures are not based on any regulations—with the exception of milk pasteurization—they depend on the farmers’ willingness to comply. Furthermore, some of these measures, particularly those concerning manure, can only be temporary.