In response to infections, temperatures rarely rise above 41º (106º F). Other studies have shown that normal healthy adults can have oral temperatures as high as 38.2º C (100.8º F).

Wunderlich emphasized this point more than 150 years ago and noted that normal temperature can range up to 100.4º F. With the publication of Carl Reinhold August Wunderlich’s (1815 –1877) landmark study, The Course of Temperature in Diseases: A Manual of Medical Thermometry in 1868, the use of the thermometer in clinical practice became accepted.Īlthough 37º C (98.6º F) is referred to as the “normal” human temperature, it is more accurate to think of the normal temperature as a range from 36º C (96.8º F) to 37.7º C (99.9º F). In 1835, Antoine Cesar Becquerel and Gilbert Breschset established the mean “normal” body temperature as 98.6º F. Anders Celsius (1701-1744) developed a second scale of measurement with the freezing of water marked at 0º and boiling at 100º with 100 gradations between these points measured as degrees Celsius (º C). Gabriel Fahrenheit (1686-1736) was the first to use mercury in a glass thermometer and developed a scale for the thermometer marking the freezing point of water at 32º and boiling water at 212º with gradations of temperature referred to as degrees of Fahrenheit (º F). Galileo Galilei (1564-1642) is credited with the discovery of the first air thermometer in the 16th century.

Temperature Measurement and Interpretation Over the past 150 years, fever has been shown to be part of a multifaceted response to infectious and non-infectious pyrogens mediated by cytokines and interferons under the homeostatic guidance of the central nervous system. Thomas Sydenham (1624–1689) recognized fever as a beneficial response to illness and thought of it as “nature’s engine fighting humanity’s enemies”. Fever is now recognized as part of a complex metabolic, immunologic and behavioral response to infection and other non-infectious illnesses. Sir William Osler (1849-1919), using fever as a symbol of infection, felt it eclipsed famine and war as an enemy to humanity. Historically, fever was felt to be an illness in and of itself, ascribed to the anger of the gods, the wickedness of the individual, an imbalance of bodily humors (blood, phlegm, black bile and yellow bile), friction from blood coursing through the veins or purification of liquids in the blood. An understanding of what defines an abnormal temperature, the pathophysiology of temperature regulation, the beneficial and harmful effects of fever and its treatment are vital to the care of the febrile patient. Fever is one of the most common and worrisome symptoms that medical providers must assess.

Freezing Point by Grace Hamilton