Detection of fever with infrared thermometry: a feasibility study

Fever is a remarkably sensitive indicator of infectious disease. The thermometer in clinical use today is basically that developed over a century ago, measuring heat conducted from skin or mucous membranes to an adjacent probe. In dealing with immunosuppressed granulocytopenic patients, the need was realized for an instrument by which temperature might be determined without a probe contact. Infrared pyrometers have been used in industry to record the temperature of mechanical objects at a distance. We tested the feasibility of using such an instrument to detect fever in humans. In a controlled and blinded fashion, infrared measurements from the eyes, axillae, and areas below the ear lobes (E spot) of 140 febrile and afebrile patients were compared with rectal temperatures recorded by a standard thermometer. The eye and E spot provided the most accurate readings. Infrared measurements of the right eye identified 57 (95%) of 60 febrile and 72 (90%) of 80 afebrile patients correctly. Overall, 92% of all patients were correctly categorized by use of the infrared thermometer at this site. We conclude that this approach is feasible and, with further technical developments, may be applicable for routine clinical use.