Q fever is a worldwide zoonosis which is caused by Coxiella burnetii and pr
esents as both acute or chronic cases. The disease can be transmitted from
animal reservoirs to humans by the inhalation of infected aerosols. The aut
hors investigated the epidemiology of Q fever in the Bouches-du-Rhone distr
ict of southern France. The study area was centered around the small town o
f Martigues near the cities of Marseille and Aix-en-Provence, where the inc
idence of the disease seemed higher than in neighboring areas, Epidemiologi
c data included sheep breeding and wind. Between 1990 and 1995, Q fever was
diagnosed in 289 patients, leading to an incidence rate of 35.4 per 100,00
0 in the study area (range: 6-132), compared with 6.6 in the area of Marsei
lle, and 11.4 in the area of Aix-en-Provence. There was a graphical and sta
tistical relation between the sheep densities, the incidence of the disease
, and the strong, local wind known as the Mistral, which blows from the nor
thwest. Although Coxiella burnetii transmission is multifactorial, we may s
peculate that the high endemicity in the study area is related to a contami
nation by aerosols because the Mistral blows through the local steppe where
70,000 sheep are bred. This public health problem requires further studies
in order to confirm this hypothesis, and to identify more individual and p
reventable risk factors.