Key Instruction Points
In 1980, an unusual illness was recognized among faculty, laboratory personnel and staff of a medical school. The illness was characterized by high fever (up to 105 degrees F), shaking, chills and absence of respiratory signs. The disease was determined to be Q fever, which is caused by the organism Coxiella burnetii. The source of the infection was found to be pregnant sheep that were being used for research. During a six-month period, clinical infections were confirmed in 65 people. Blood tests revealed that a total of 137 people had been exposed. Of these, only 41 worked directly with the sheep. The remainder of exposed people worked in areas where the sheep had passed by or were exposed in other ways. As a result of this outbreak, all sheep research was moved to a research farm.
Q-Fever is a rickettsial disease found in ruminants such as cattle, sheep and goats. (Rocky Mountain Spotted Fever is another rickettsial disease.)
Q-Fever is so common in ruminants that it is difficult to find herds free of it. In cows' milk, pasteurization kills the organism. While giving birth, infected animals shed high numbers of organisms into the placenta and fetal fluids.
In a production-type sheep facility, with movement of animals in and out of the flock, it is not practical to eliminate Q-fever from the flock.
The acute illness in people is treatable with antibiotics. However, it often goes unrecognized. Chronic, long-term complications include infection of heart valves. People with pre-existing heart conditions are at increased risk of chronic infection.
Sheep are popular animal models for research in obstetrics. For this reason they have been associated with outbreaks of human disease in medical school settings. Infection control necessitates separating animal use areas from "people" areas.
Personnel who work with sheep must receive instructions on procedures to follow when working with them. Housing and research arrangements must provide good separation from non-animal work. Personnel who might be at risk of chronic Q-fever complications must be alerted. Immunocompromized persons or those who have a history of heart disease (e.g. rheumatic fever or heart surgery) should consult a physician about the advisability of working with sheep and other ruminants.