Diseases naturally transmitted between animals and humans (zoonoses) are one of the leading causes of emergence or re-emergence of human infectious diseases. Non-foodborne zoonoses are commonly transmitted to human directly by contact with infected animals or contaminated environment. People working with animals such as farmers and veterinarians are particularly at risk of infection. Some zoonoses can also be transmitted indirectly thought the air and therefore can affect the general population. Example is Q fever, a disease caused by Coxiella burnetii, a bacterium highly resistant in the environment.

In Western France, Q fever is endemic in cattle herds. To improve human zoonotic disease surveillance, the investigators will conduct a population based study in this area.

The aims of the study are:

1. To assess seroprevalence of Coxiella burnetii infection among general population, farmers and veterinarians in Western France
2. To identify risk factors for Coxiella burnetii seropositivity in these populations

In order to estimate seroprevalence and risk factors for Coxiella burnetii infection in humans, the investigators will conduct a cross-sectional study in three groups:

• blood donors at blood donation organizations (general population)
• beef and dairy cattle farmers
• veterinarians involved in a rural practice

All the participants in the study will provide a blood sample and will fill in a questionnaire.

Inclusion Criteria:

• Give a written informed consent
• Be 18 years old and over
• Be able to speak French

Exclusion Criteria:

• Adults under protection (guardianship or curators)
• Contraindication for drawing blood

• blood donors at blood donation organizations (general population)
• beef and dairy cattle farmers
• veterinarians involved in a rural practice