FEVER OR PYREXIA.
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I. GENERAL DISEASES.
A. IDIOPATHIC FEVERS AND ALLIED DISEASES.
Acute Specific Fevers. Acute Exanthemata.
Before proceeding- to discuss the several diseases included under the above group, it will be expedient in the present connection to consider the following subjects, viz., Fever; Contagion; and Epi- demics.
Chapter I.
FEVER OR PYREXIA.
The phenomena characteristic of fever may be observed in connec- tion with two distinct classes of cases : — First, they may follow and be the result of some local lesion in a tissue or organ, especially inflammation, when the fever is termed secondary, symptomatic, or merely pyrexia, fever, or the pyrexial state. The fever attend- ing pneumonia will serve to illustrate this group. Secondly, they may constitute the chief and primary deviation from the normal state, not being due to any evident local cause, and if any special organ or tissue becomes morbidly affected, this occurs secondarily. Idiopathic, essential, primary, or specific are the terms applied to fever under these circumstances, or it is simply denominated a fever. It then originates from the presence of some morbid poison in the blood, either introduced from without, or developed within the body. The acute specifics and rheumatic fever afford examples of this class.
Essential phenomena and Symptoms. The precise symptoms which may be observed in different febrile diseases are necessarily very variable, but there are certain phenomena which are charac- teristic of the pyrexial condition, whatever the cause may be to which this is due, and to these phenomena attention will now be directed. They may be arranged thus : —
I. Rise in Temperature. — This has been generally looked upon as the only absolutely essential sign of fever, excessive heat of the body being considered as characteristic of the febrile state. It may be evident in the aspect or sensations of the patient, or the skin may feel hot to the touch ; but no reliance ought to be placed on these sources of information, and the existence of pyrexia can only be satisfactorily determined by the use of the thermometer. The temperature may range from only just above the normal to 108°, 110°, or 112° Fahr., and possibly even much higher than this, but it does not often exceed 105° or 106°. It may continue to rise for some time after death.
