Q fever, also known as koala fever, is a natural epidemic disease of human and animal origin caused by a pathogen called Burkholderia coxii. It was first identified in Australia as early as 1935-1937, and to date Q fever has spread to almost all countries worldwide. Acute Q fever presents with fever, headache, muscle aches and pains, often accompanied by pneumonia and hepatitis; chronic Q fever presents with endocarditis, granulomatous hepatitis, and osteomyelitis. The infectious agent of Q fever is mainly infected domestic animals such as cattle and sheep, and its pathogen, Burkholderia coxii, is carried in cattle, sheep, and even rodents and birds, and is present in their urine, feces, milk, and is particularly high in the placenta. The pathogen of Q fever is usually transmitted through aerosols, such as clouds in the sky, smoke and dust in the air. Humans who inhale such aerosols or particles, or eat food with pathogens, can develop Q fever, with an incubation period as short as 1-3 weeks and as long as 4 weeks.