Q fever (Coxiella burnetii), also known as Query fever and rickettsia, is a bacterial disease that occurs naturally in sheep, cattle, and goats. It is present in high concentrations in the placental tissues of these animals. Incidence of the disease is worldwide, and it is likely that more cases occur than those reported. Many epidemics occur in stockyards, meat-packing plants, and medical labs using sheep for research. Transmission occurs from airborne dissemination of rickettsiae in dust from contaminated premises. Organisms can be carried in the air over half a mile downwind. Infections are also contracted from contact with infected animals, their birth products (especially sheep), wool from sheep, straw, fertilizer, and laundry of exposed persons. The disease has also been traced to unpasteurized milk from cows. Transmission from human to human is rare. Several varieties of ticks may also carry the disease and transmit it from animal to animal. Mortality rates from this disease are low, from % to 3%. It would, however, be an effective incapacitating agent because it is highly infectious when delivered through inhalation; as little as one organism can cause climical symptoms.