CONDITIONS OF DISEASE.
The conditions of disease referred to in the last chapter and now inviting definition and brief exposition may be classified under fifteen heads.
It is customary to say of persons suffering from various acute diseases and from some slow or lingering diseases, that they have fever; that the fever runs high; that the fever is reduced; that the fever is intermittent, and so on.
Under this term fever, the older writers sometimes meant one special disease, which they defined no further. Afterwards fever began to be considered under two heads, according as it was or was not communicable. Thus there were contagious fevers, or such as were communicable by touch and could be conveyed by something that was capable of being carried from the affected to the healthy; and there were infectious fevers, or such as could be contracted by corning into immediate contact with the poison that was emanating from the affected. Again, there were fevers which were neither contagious nor infections—simple fevers; or which ran a continued course, continued fevers. By another change of expression fever was connected with diseases of particular organs, as with the brain, brain fever, or with particular functions or states, by which method of expression we got such terms as milk fever and child-bed fever. Once more fever was connected with another general term, inflammation, so giving rise to the term in flammatory fever; or it was considered to be the result of some irritation, from which view was derived the expression irritative fever.
In these days we have not lost these expressions, but we use them, when we are speaking correctly, with more precision. We have now learned to take with the thermometer the temperature of the human body, and we accept the natural temperature to be 9s.4° Fahrenheit in temperate climates, with a range of two tenths on either side, below for arctic, and above for tropical con: ditions. It is the fact even in what may be considered health that these ranges may be extended on either side for short periods of time, but practically the figures are sufficiently correct. When therefore the temperature of the body is shown by an accurate thermometer to be 9s.4° Fahrenheit, we consider there is a natu ral temperature. When the temperature is above 9s.4° in any marked degree we say there is fever.
We must not boast that by this definition we have added much to human knowledge, for the most ancient physicians and scholars gave us a similar, if less precise, statement, and went so far as to discuss whether fever could exist of itself without any preceding change in the body, such as inflammation. But we have gained, by the labors of many hard-workers, by those of the late Dr. Wunderlich especially, a correctness in the reading and the detection of the range of fever that was never before attain able. From its intensity we now measure fever and its dangers with almost exact detail : so much fever, so much or so little danger, so much probability of recovery, so much probability of death.
By the term fever in these days we mean an elevation of ani mal temperature varying in degree, and when the word is used alone we mean nothing else. If the fever is one, two, or three degrees above the natural, we look upon it as mild in form. If it runs up to four and five degrees above the natural, we say it in dicates danger; if it rises over six degrees, the danger is immi nent; when it passes seven, the chance of continued life is very small; and, at eight degrees, if the condition continue very long, death is all but certain. At an increment of eleven degrees of heat above the natural, on Fahrenheit's scale, continuance of life is, with the rarest of exceptions, impossible. Before that stage is reached the minute blood-vessels have undergone contraction; the muscles of the body, generally, have shown a tendency to spas modic contraction which may pass into tetanus; and the blood has, in some instances, commenced to separate into two parts, or, as it is commonly said, it has commenced to set, or coagulate.
Fever thus viewed becomes a condition of disease running with other conditions which may, locally, be more apparent, but which in a general sense cannot be more definite. It is not a basic condition, for it is a result of something that preceded it. But it determines the after results so decidedly that to retain it as if it were basic, and to speak of irritative fever, inflammatory fever, contagious fever, intermittent fever, hectic fever, tetanoid fever, scarlet fever, spotted fever, malarial fever, and the like, is quite correct if we only keep in mind the simple truth that the added words merely express either the origin, or the course, or the phenomena of the febrile state.
A good simile is given to us of this in the example of a com mon fire. Fire is not a base; it is a result; and yet it determines consequences so decidedly that it very soon becomes the one domi nant fact. Fire may be sharp, slow, bright, smouldering, acci dental; it may be a coal fire, a wood fire, a peat fire; it may be continued, intermittent, subdued, wild; and by all such terms we may distinguish its character. Instead of serving its intended purpose in the house or manufactory, it may be playing the part of a destroyer. Fever is the counterpart of this in the house of life; it is the animal fire burning beyond what is natural, excited to that burning by something that was, in a basic sense, the prime cause of the condition of disease.
The influences which set up fever in the animal body are many. If sensitive nervous surfaces be rubbed or irritated so that pain results there is an increase of temperature, irritative fever, a fever probably of short duration and harmless in kind, lasting only so long as the irritation lasts and dependent on the disturbed nervous balance, but still present. If, from local causes, an organ of the body becomes inflamed, there is soon . some increase of temperature, or fever, infiammattory fever, which will vary in intensity with the extent of the inflammation, and will probably subside with the inflammation, but will not fail to be present. If some foreign substances, minute particles of matter, fever-poisons, - be introduced into the body, they may modify the animal chemistry, so as to increase the animal com bustion and produce fever, contagious or infectious fever, which will last so long as the cause of the disturbance remains in opera tion. Such fever may, in some instances, subside from reduction of the cause, and then break out again as the cause is reproduced, or it may by its violence, either before or after the cause has ceased to operate, give rise to a destruction which renders death inevitable. If the body be exposed to agents which modify the vascular tension so that through the vessels the blood shall pass with undue friction, there may be an increase of fever which might be called frictional fever. Or, if the tension of the vessels be suddenly reduced by some agent, say alcohol, or cold, so that the heart shall intensely inject the minute vessels with blood, there may again be, from the reaction, an increase of tempera ture, fever of reaction or congestive fever. Lastly, if the body be subjected to the influence of some agent which, interfering for a time with the animal chemistry, causes a development of fever, then ceases to act, as if it were itself destroyed, but after a time is reproduced and sets up once more the increase of temperature, there is excited what is known as recurrent, relapsing, intermit tent, or hectic fever.
Thus it will be seen that the word fever indicates a condition of the widest significance, while in itself it is not strictly speaking a disease. It is an exalted state of that natural function by which all the flexibility of life, the chemistry of life, the construction of matter into living form, the destruction and removal of matter in dead form, is regularly carried on. In fever, the body is, hi short, living out of its compass, and wherever in these pages the term fever is used, let it be remembered as meaning fire, over action, expenditure beyond the natural capacity of vital process.