People can also get Q fever by drinking infected milk, but most infections are spread through the air. Person to person transmission occurs rarely, if ever. People can have Q fever without knowing it or mistake it for mild flu. Often, it is impossible to tell without laboratory tests. Sometimes, Q fever strikes as a sudden illness, affecting a large number of people in the same workplace.
Some patients develop a slight, dry cough because of a lung inflammation known as pneumonitis.
Most symptoms disappear after 7-10 days. However, afflicted people can feel generally ill with loss of appetite for several weeks. A small percentage of patients develop hepatitis or liver disease and jaundice, a yellowing of the skin and darkening of the urine, caused by a malfunctioning of the liver. Other rare clinical syndromes including endocarditis, an inflammation of the lining of the heart cavity, have been reported. Laboratory tests for Q fever measure antibodies that circulate in the blood.