Q fever is a disease caused by "Coxiella burnetii", bacteria that affect humans and other animals. It is not common but can be found in cattle, sheep, goats, and other household animals, including cats and dogs. People can get infected if they inhale endospores or touch the milk, urine, feces, vaginal mucus, or semen of infected animals. The disease is rarely carried by ticks. A human can be infected by a single bacterium.