The increased metabolism and consequent tissue waste involved in the febrile process makes the consideration of the diet in acute infectious disease a matter of great importance, of greater importance, indeed, than any method of treatment. Except in the case of diphtheria, for which we have a really scientific remedy in antitoxic serum, we cannot hope by drugs or otherwise to limit the course of the disease. We can only stand by and put the patient in the best possible condition for combating it. The primary necessity, then, is to support the patient's strength, which can only be done by a suitable system of feeding and stimulation. If the fever is prolonged, this may be a matter of considerable difficulty, as there is no doubt that the gastric digestion is often much impaired by continued pyrexia and toxaemia, and salivary digestion is liable to be reduced to a minimum, the saliva being often much diminished and occasionally assuming an acid reaction. Pancreatic digestion also suffers, and in a prolonged fever it is chiefly upon intestinal digestion that the patient depends. Mastication, again, cannot be counted on in patients who may be much exhausted and often delirious. There is always, moreover, in the early stages of an acute fever loss of appetite, and only too often disgust for food. Under these circumstances there is not much difficulty in concluding that the food given should be easily assimilable and, for the most part at least, fluid. The second great necessity in treating a case of fever is to assist, so far as possible, the processes of elimination. It must be remembered that the increased tissue waste must lead to an increase of the amount of urea in the blood which also contains, perhaps in large quantities, the toxins of the disease. The regime prescribed should favour, if possible, the elimination of these deleterious substances, and there is probably no better way than by supplying the patient with an adequate amount of fluid, preferably cold water.
When the patient reaches the convalescent stage, our object is to restore him as rapidly as possible to his full strength, and to repair the inevitable waste of tissue caused by the fever. A liberal diet is therefore in most cases indicated, although in certain diseases the amount of food allowed may have to be limited in view of the various complications which are liable to appear in this stage. In any case the transition from fluid to solid food must be made gradually, and the effect of each addition to the diet carefully watched.
If a patient is to profit by his food, it is highly necessary that his desire for it be so far as possible stimulated, and that he be put in the best possible condition for appreciating it. In this connexion no point is of more importance than the toilette of the mouth. A fever patient, with dry baked tongue and sordes on lips and teeth, will enjoy his food far better if his mouth is carefully cleansed. Regular cleaning, moreover, helps to check the irregular fermentative processes which occur in the mouth, and which are liable to render the salivary secretion acid instead of alkaline. In severe cases, the mouth and tongue should be carefully cleaned every four hours with a soft piece of clean rag, and afterwards anointed with some mildly antiseptic ointment. A mixture of equal parts of glycerine and boro-glyceride is useful for this purpose, as is also the ointment which I am accustomed to use at the Edinburgh City Hospital, and which consists of one drachm of boracic acid to the ounce of vaseline, flavoured with five drops of peppermint oil. An adequate supply of fluid drinks, water for choice, does much also to keep the tongue moist and clean. The serving of the food is also of importance. The glass and crockery used should be scrupulously bright and clean. Neglect of this is quite sufficient to disgust a fastidious patient, and render him consequently much more difficult to feed.
The food should be given in measured quantities at measured intervals, and the amount given at one time should be small. The rule should rather be "little and often." An interval of two hours between the feeds is a convenient time, but this may be in some cases more prolonged, the amounts given being slightly larger. As a general rule, the feeding should be continued throughout the night, but it will usually be sufficient to wake the patient at four hour intervals. As a matter of fact, fever patients are often so restless and have their sleep so much broken, that a good nurse finds no difficulty in supplying them with sufficient nourishment without finding it necessary to wake them. If a feed has been missed, it is advisable not to increase the next one to such an extent that the loss is made up. It is extremely easy to overload the stomach, and as a rule, the patient stands the loss perfectly well. In special cases, where, for instance, a hypnotic has been given, or when sleep has been previously insufficient, it would be madness to wake the patient to feed him, unless his colour becomes very bad or his extremities cold. Sleep in such a case probably conserves his energy better than food.
In ordinary cases, where the fever is not unduly prolonged, there is little or no advantage in giving more than fluid food. In a prolonged fever like typhoid, or in the severe secondary fever of smallpox, this may have to be supplemented by soft solids, especially if the wasting is extreme, or if for any reason the patient enters upon the disease in an especially debilitated condition. But in diseases in which the febrile process is usually of short duration, as in measles or in lobar pneumonia, a fluid diet will be found perfectly adequate in the acute stage. The most satisfactory form of fluid feeding in the long run is unquestionably a milk diet, and in children particularly this need be seldom exceeded. Milk, containing as it does protein, fat and carbo-hydrates, at first sight would appear the ideal form in which to administer fluid food, but, as will be seen later, when the feeding of enteric fever is discussed, many theoretical objections to its exclusive use have been raised. Clinically, however, it is by far the best fluid food we can command and, if given properly, it is perfectly well digested by most patients. The safest way of giving it, and the precautions which its use demands, will be found in the section on enteric fever, the dieting of the acute stage of which may be taken as applying to all acute febrile conditions. The milk may, under certain circumstances, be supplemented by the various meat broths, beef, mutton, veal or chicken, and an occasional change in the basis of the broth given does much to vary the monotony of the diet. The food value of these additions to the diet is, no doubt, very small, but they are usually much appreciated by the patient. The different extracts of meat and meat juices may also be employed with advantage, if the use of the fresh juice of raw beef is not preferred. Another useful adjuvant to a milk diet is albumin water. This may be prepared by shaking up the beaten white of a fresh egg in about 8 oz. of water to which a little crushed ice has been added. The whole may be flavoured with lemon or orange juice or with a small amount of sherry or brandy. Its employment may possibly to some degree provide compensation for the great loss of nitrogenous substances. I seldom, however, employ it myself except in prolonged cases. In such cases, also, protein preparations of the class of somatose, sanatogen, or plasmon may be suitably added to the diet. Often a patient who dislikes one of these foods will quite readily tolerate another, and the medical attendant also may have his own preferences regarding them. I have always found Benger's food a most useful preparation, and employ it perhaps more frequently than any of the others named, though the cheapness of plasmon does much to commend it for hospital practice. If, in spite of the addition of these various food substances to the milk, the patient appears inadequately nourished, raw eggs beaten up in milk and flavoured with brandy may be added to the dietary. Bread and milk, arrowroot, and other starch preparations, and jellies are also often admissible. As regards the latter, gelatine has a good reputation as compensating tissue waste. The jelly may be prepared from calves' feet or from commercial gelatine. It may be flavoured either with wine or with fruit juices.
As regards drinks, pure cold water is probably in the long run the most satisfactory, and should always stand at the patient's bedside. If he is unconscious or delirious, it must be forced upon him. Aerated waters are, of course, largely used, and without any enthusiasm for them, I must admit that a mildly alkaline water is probably often of advantage. They tend occasionally, however, to the production of too much wind, and in conditions where the digestion is upset they are better avoided. A little lemon or orange juice in large quantities of water sometimes assists in allaying thirst, and in any case is grateful to the patient. But it is a question if we should endeavour to allay thirst, as it is by ingesting large quantities of fluid that the patient facilitates the elimination of toxins and waste products. Tea may be allowed in moderation in most fevers, and is best given with plenty of milk. Cocoa is tolerated if the digestion remains fairly good, and a little strong coffee made with a very large proportion of milk is occasionally useful for patients who have a great dislike to milk given alone.
With the return of the temperature to normal the first solids may be given, if the prolonged nature of the illness has not made their previous use permissible. Sponge cake or sponge biscuit, given with a cup of tea or a glass of milk, is a useful first addition to a fluid diet. Milk puddings, fish soups, meat soups flavoured with vegetable juices and thickened with rice or oatmeal, finely minced raw meat sandwiches, oysters, well stewed fruit, and potatoes, well boiled and mashed with meat gravy or butter, are all suitable for the dietary of early convalescence. Thereafter fish, whiting for choice, sweetbreads, and in a few days white meat such as chicken. From chicken the patient may progress to a chop, after which his digestion may reasonably be regarded as capable of dealing with any ordinary diet.
The above suggestions indicate very briefly the diet which may usefully be employed in pyrexial conditions. Each disease, however, has its own peculiarities, and may from the nature of its pathology and complications demand special treatment. The dietary suitable for each is discussed in more detail in the following pages. As regards stimulation, the indications for its employment differ very considerably in the different fevers. Suffice it to say here that as a rule it is unnecessary in the acute infectious diseases, that children particularly are often better without it, but that in some conditions its use is indispensable.