Diurnal Temperature Variation and Using Fever to Screen for Infectious Diseases

Fevers have been used as marker of disease state for hundreds of years and are frequently used to screen for infectious diseases during outbreaks. However, body temperature and fevers have been shown to vary over the course of a day and across individuals by age, sex and other characteristics. The objective of this paper is to describe the individual variation in diurnal temperature patterns during episodes of febrile activity using a database of millions of recorded temperatures across the United States. We then model the probability of recording a fever during a single reading at given time for individuals who are experiencing a febrile episode. We find a wide variation in body temperatures over the course of a day and across individual characteristics. Similarly, the likelihood of recording a fever may vary widely by the time of day when the reading is taken and by an individual's age or sex. These results suggest diurnal temperature variation and demographics should be considered when using body temperature to screen for disease, especially for diseases that are contagious.