FEVER, a condition in which the tempera ture of the body is above normal. The average daily range of temperature in men is from 98' to 99° F., and in women from quarter to half a degree higher. In children temporary eleva tion even as high as 100° F. may occur from conditions of excitement and from over-exercise, but this should not be termed fever. Slight daily variations in temperature are usual. Thus the maximum temperature occurs usually from 5 to 9 P.M. There is then, as a rule, d sleep a decrease until a minimum is reached, some time between 2 and 4 A.m. It is probable that diminished muscular activity and lessened food absorption are responsible for much of this variation. Temperature usually rises during strong muscular exercise and also after a meal. These slight rises are balanced by heat-loss from increased perspiration. The temperature of man in the tropics and in the Arctic zone does not vary more than 1° C. (For discussion of bearable extremes of heat and cold, heat production, heat-loss and the nervous mechan ism that controls the general phenomena, see ANIMAL HEAT).
Modern pathology teaches that fever is the index of a reaction of the human body in its struggle with some foreign invader and is brought about by excessive oxidation and diminished heat-loss. Fever is usually accom panied by an increase in the number of respira tions, by an increased number of contractions of the heart, raised pulse-rate, an increase in the blood-tension in the blood vessels and by other symptoms of general malaise. These are head ache, dry mouth, dry skin and at times in creased mental excitement. Fever from this point of view is a conservative process and is nature's own method of overcoming some form of infection or intoxication. Fever as a gen eral process should be distinguished from the many special kinds of so-called fevers that are described. Thus the term fever as used in typhoid fever, scarlet fever, lung fever, etc., is a relic of earlier medical teachings, in which the rise in temperature was considered the es sential part of the disease. It is now recog nixed that fever is only one of the features in the general history of the development of the disease-process. The height of the temperature during fever may vary considerably. If the temperature is not above F. (37.7° C.), it is spoken of as light fever; when between 100° and F. and 39.4° C.) it is called moderate fever; between and 105° F. and C.) it is spoken of as high fever ; while above 105° F. C.) hyperpyrexia is the term that is applied. Temperatures as high as F. have been recorded in patients who have recovered. The course of most fevers is, for purposes of convenience, divided into (1) the initial stage, which usually starts with chilliness and often with a distinct chill; (2) the hot stage, when the temperature has risen and is at a fairly constant normal, during which the blood vessels at the surface are dilated, the skin is flushed and feels hot and dry; this con dition perhaps lasting a few hours, or it may be several weeks, according to the disease-proc esses that produce it; and (3) the terminal stage. This may be ushered in by a previous
perspiration, with sometimes increased urination and prompt subsidence of the temperature; or the temperature may slowly sink to normal by a process of lysis. Each type of disease process manifests its own peculiar temperature variation and the study of temperature-curves is extremely important in the determination of the disease.
Fever results not so much from an increase in the heat-production alone, but in a disturb ance of the heat-regulation or thermotaxis for it is perhaps true that the amount of heat produced by an athlete in a mile run is vastly greater than that produced throughout the entire four weeks of a severe typhoid fever yet the heat-loss keeps pace in the runner with the heat-production. It is the relation between these two factors that is disturbed in fever. Fever is largely a conservative process and a moderate degree of temperature is believed to be rather beneficial than harmful. The real danger in fever is not the temperature, unless it is excessively high — from 104° to 105° F.— but it is the poison that is being made in the body, either by perverted metabolism or by bacterial or chemical intoxication. Therefore, in the treatment of disease with rise in tem perature the reduction of the fever is not the only point to be attained. During fever there is increased oxidation, increased elimination of uric acid, diminution of most of the secre tions, notably the saliva, the gastric juice, the bile and save in the terminal stages, the sweat. The kidney-secretion is also decreased during the hot stage, because more water is being lost through the skin and lungs than usual. Changes in the blood are constant and usually consist in an increase in the number of leuco cytes, or white blood-cells. High temperatures may produce degeneration in a number of tis sues of the human body. The most important ones are those of the nerve-cells. These changes may take place if the temperature gets above 105° F., and even lower temperatures acting for a very long time may cause serious structural changes in the nervous system. The treatment of fever, as has been 'indicated, should mean the treatment of the disease that is causing the fever and will be considered under each particular topic of fever. (See MALARIA;