Wind in November, Q fever in December

Abstract

Q fever, a worldwide zoonosis caused by Coxiella burnetii, can be transmitted from animal reservoirs to humans by the inhalation of infected aerosols. We investigated the epidemiology of Q fever in the Bouches-du-Rhone district of southern France, particularly the role of wind and rainfall in C. burnetii transmission. During the winter of 1998 to 1999, an unexpected number of cases were diagnosed in the area. This statistically higher incidence was associated with an increased frequency of the mistral 1 month before onset of disease, i.e., shortly after the main lambing season. These data confirm that wind plays a role in C. burnetii transmission, a factor that can be monitored but not prevented. Further studies are needed to identify and confirm preventable individual behavioral risk factors for Q fever.

Figure 1

Etang de Berre area of France, showing the location of "La Crau" (sheep-breeding area), and the direction of the mistral wind. The black dots represent the human Q fever cases (places of residence). The white dots represent the 7 cases which occurred in December 1998 to January 1999.

Figure 2

Seasonal variations of Q fever incidence and sheep births in the Etang de Berre area of France: cumulative cases for 1996–1999.

Figure 3

Monthly distribution of Q fever cases in the Etang de Berre area of France: comparison between the years 1996–1999, showing an unusual peak in December 1998 and January 1999.

Figure 4

Rainfall (in mm) in October, November, and December 1996 to 1999 in Istres.

Figure 5

Mean monthly rainfall in Istres (1995–1999).