Behavioral Effects of Tularemia and Sandfly Fever in Man

Decrements in work performances of 16 volunteers with induced tularemia and 16 with sandfly fever were measured with well-standardized techniques for evaluation of performance of synthetic work. Findings were compared with control values from the same individuals before illness and with control data from normal hospitalized and nonhospitalized volunteers. After exposure, men continued to work normally during incubation periods; decrements in performance first appeared in coincidence with onset of illness and became maximal when symptoms were greatest. Patterns of decrements were similar in bacterial and viral illnesses, but the degree was greater on the average with tularemia than with sandfly fever (drops to 69% and 80% of baseline, respectively). Measured decrements were general, rather than specific to any of several behavioral functions, and average decrements were clearly related in timing and magnitude to the presence and severity of illness. Estimates of motivation and extensive clinical and psychological tests provided no insight with regard to differences among individual volunteers in the ability to maintain performance at levels observed before illness; such differences were essentially maximal in range, even with as few subjects as the 1·6 in the studies on tularemia. Among subjects who were equally febrile, some showed no decrements in performance, whereas others were unable to work at all.