What is the primary source of infection for Coxiella burnetii?

Coxiella burnetii, the bacterium responsible for Q fever, is primarily transmitted to humans through the inhalation of contaminated aerosols. This transmission route is particularly concerning in environments where there are large populations of livestock, as the bacteria are shed in various ways, including through birth fluids and respiratory secretions of infected animals. When these aerosols containing the bacteria are released into the air, they can be inhaled by individuals nearby, leading to infection.

While other transmission routes, such as the consumption of unpasteurized dairy products, can also lead to infection, they are not the primary source. Infections via the fecal-oral route and from contaminated soil are less common and not considered major pathways for Coxiella burnetii transmission. Therefore, the inhalation of contaminated aerosols is recognized as the most significant method through which humans contract this pathogen.