Other animals or humans can be infected by inhaling aerosols from the amniotic fluid or from unpasteurized infected milk. The amniotic fluid of infected animals carries a very high number of organisms and is particularly dangerous. The other route of transmission occurs among wild animals. The disease may be spread between infected rabbits, rodents, and other wild animals by the bites of ticks. Humans are not usually infected by tick bites, although it is possible.
Infected humans develop a flu-like illness which can be mild or severe in different individuals.
Many humans have mild infections and recover without ever realizing that they have had Q Fever. A substantial portion of rural workers and those that work with ruminants have already had the disease, developed antibody, and are immune to further infection. Disease is most likely to be seen in urban workers who are working with ruminants for the first time. While most human cases are mild and flu-like, the disease can be a serious one. Clinical signs begin from two weeks to one month after exposure.