ABSTRACT

In 1933, a disease of unknown etiology was observed in abattoir workers in Queensland, Australia. Patients presented with fever, headache, and malaise. Dr. Edward Derrick, the director of Health and Medical Services for Queensland, was sent to investigate this previously undescribed disease, Q (query) fever. In the first use of laboratory animals to discover the cause of the disease, blood and urine from patients were injected into guinea pigs. It was noted that infection caused a febrile response that could be passed to successive animals [1]. However, the etiological agent could not be isolated, and Dr. Derrick assumed that the causative agent was a virus. About the same time, in Montana, ticks collected in an investigation into Rocky Mountain spotted fever were injected into guinea pigs. One of these animals became febrile, and the infection could be passed to successive animals. A breakthrough occurred in 1938, when Dr. Cox was able to cultivate

Coxiella burnetii

in large numbers in yolk sacs of fertilized hen eggs [2]. However, although the infectious organism was isolated, the disease that it caused remained unknown. In 1938, a researcher in Montana was infected with the tick isolate, and guinea pigs were infected by an injection of a sample of the patient’s blood. Ultimately the agent causing the unidentified disease in Australia was shown to be the same as the one isolated from

ticks in Montana by the demonstration that guinea pigs previously challenged with the Montana isolate were resistant to challenge with the Q fever agent [3].