A system of practical medicine. By American authors. Vol. 1

by Unknown

The facts in reference to the spread of epidemics of influenza and the course of the disease in infected localities are comprehensible upon no other theory than that of a specific infecting principle as its exciting cause. What this principle may be is not yet known; where it originates is equally unknown; and our knowledge of the influences that from time to time call it into activity and send it forth in definite directions over the earth is no less negative.

So general a disease can only be disseminated by the most general medium, the atmosphere, and its exciting cause must be capable of reproducing itself in that medium, otherwise it would be lost by dispersion in traversing distances measured by the boundaries of continents and oceans. The rapid diffusion of influenza, sweeping over continents in a few weeks at one time, its slow migration, creeping about a city and its environs for months, at another, are to be most easily explained upon the theory of a living miasm capable of being transmitted by the air, and possessing at the same time an independent existence. Such an entity would find certain localities more favorable to its growth, reproduction, and prolonged existence than others. From this point of view influenza is a miasmatic disease. The infecting principle of this disease is also, to a slight extent, capable of being reproduced in or about the human body and transmitted by personal intercourse, as well as conveyed from place to place by the persons or clothing of those affected or those travelling from localities in which the disease prevails. We are thus led to the conclusion that it is also contagious, though feebly so.

CLINICAL HISTORY.—Influenza, in individual cases, presents the greatest variation as regards intensity, from the most trifling indisposition to an illness of the gravest kind, terminating in death. These variations are dependent upon—1st, the previous health of the individual, his age, and the power of resisting depressing influences which he possesses; 2d, the energy and the amount of the specific cause of the disease to which he has been exposed—in other words, the dose of the fever-producing poison; and 3d, the character of the prevailing epidemic.

It is important to observe that cases of very great severity are occasionally encountered during the prevalence of mild epidemics. In every epidemic, on the contrary, a considerable part of the community suffers from influenza in the mildest, or what has been called the rudimentary, form. This is characterized by general malaise, an easily oncoming weariness upon bodily and mental effort, a disinclination for business, some inability to fix the attention, and slight mental confusion; to these nervous disturbances are added catarrhal symptoms, as coryza, sore throat, a tickling cough, and the like; but the indisposition is subfebrile—it does not amount to a fully-developed fever. Other cases present the symptoms of an ordinary attack of acute coryza, laryngitis, bronchitis, pharyngitis, with unusual constitutional disturbance, distressing headache, and pains in the back and limbs. The fever in this class of cases does not range high, yet the patients are ill enough to betake themselves to bed.

In severe cases the onset is usually abrupt. The attack begins with shivering or a chill, or with fits of chilliness alternating with heat. Fever is rapidly established. It is usually moderate; sometimes it reaches a high grade. It shows a tendency to morning remissions. Sensations of chilliness occur; they are called forth by slight changes in the external temperature. They are often followed by flushes of heat, and are, in many cases, attended by annoying sweats. The febrile outbreak is sometimes preceded by intense frontal headache, with pain in the orbits and at the root of the nose. In other cases these pains quickly follow the chill. Sneezing, redness of the eyes and edges of the nostrils, a more or less abundant thin discharge from the nose, and lachrymation, now occur. In some instances there is bleeding from the nose. The throat becomes sore; there is a tickling sensation in the upper air-passages; a dry cough sets in, attended by more or less hoarseness and shortness of breath. The cough is paroxysmal, hard, distressing. It sometimes causes vomiting, like that which occurs in the paroxysms of whooping cough. Chest-pains, stitches in the side, frequent sneezing, loss of the sense of smell and of taste, attend the development of the general catarrhal manifestations.

The fever is attended by great depression, pains in the limbs, loss of appetite, thirst, constipation, and diminished secretion of urine. The pulse is full, but, as a rule, only moderately increased in frequency. There is in many cases slight, or even decided, blueness of the lips and finger-tips. The patient is distressed by restlessness and want of sleep. At the end of four or five days the febrile symptoms decline, at times gradually, oftener rapidly, with copious sweats or spontaneous flux from the bowels. The fever continues, however, when severe complications have taken place, ten or twelve days. The defervescence is marked by an increased flow of sedimentary urine and considerable amelioration of the subjective symptoms. The catarrhal symptoms outlast the fever two or three days, but cough and expectoration may not disappear for some time.

With these symptoms are associated the evidences of functional disturbance of the nervous system. There is remarkable nervous depression; loss of strength and lowness of spirits are combined with mental weakness, or even stupor and delirium. In some cases slight convulsions take place. Cutaneous hyperæsthesia occasionally occurs, and areas of burning pain in the skin are to be met with. Neuralgia, muscle-pain, and aching referred to the bones are very common and often severe.

In other cases abdominal symptoms are prominent, while those referable to the head and chest are less urgent. The disease assumes the guise of a more or less severe catarrh of the gastro-enteric mucous membrane, with disturbance of the functions of the liver. The fever and the peculiar nervous depression are, however, the same. Cases likewise present themselves in which but little of the usual tendency to localization of the catarrhal processes is to be observed; there is fever of varying intensity, with great depression, and simultaneous and equal implication of the head and the organs of the chest and abdomen.

Many writers have sought to arrange the foregoing different forms of influenza in definite categories. It would be a useless task to reproduce their views upon the subject, or even to enumerate the varieties that have been described. In practice, the various described types merge so gradually into each other, and are so modified by the individual peculiarities of the sick, and by the complications which arise in the course of the attack in consequence of such peculiarities or of previously existing diseases or tendencies to special forms of disease, that, in point of fact, particular cases cannot usually be referred to theoretical categories. Hysterical persons and those of a nervous constitution are prone to suffer especially from the peculiar nervous symptoms of influenza. The disease is also modified by the age of the subject of the attack; children manifest in a high degree the signs of cerebral congestion, while old persons are subject in a peculiar manner to dangerous pulmonary complications, and those of a gouty or rheumatic constitution suffer more than others from muscular pains.

The duration of the mildest form of influenza is from two to three days; in well-developed cases without complications convalescence sets in between the fourth and tenth days; while severe cases with complications last much longer, several weeks often elapsing before recovery is complete.