Part 134

In October, 1880, influenza being prevalent in Philadelphia, both epizoötic and epidemic, but very mild both among horses and men, I attended a medical student who, having had what he regarded as a cold for about a week, had kept at his work without treatment, until, upon the occurrence of a chill followed by grave thoracic symptoms, he was obliged to betake himself to bed. I first saw him the following day in the hospital of the Jefferson College. There were the symptoms of acute lobar pneumonia, with the signs of extensive consolidation of the left lung and pleurisy of the right side. Moreover, there were delirium and jaundice. The urine was non-albuminous. The next evening he died. At the same time many members of the class suffered from influenza, and a careful inquiry into the history of the case of this young gentleman satisfied me that the pneumonia had arisen as a complication in a neglected and moderate severe catarrhal fever. Until the eighth day before his death he was in excellent health. No examination of the body was permitted.

Graves thought that a kind of paralysis of the lungs, with great oedema, takes place in some cases, and attributed it to an affection of the vagus. It was his conviction "that the poison which produced influenza acted on the nervous system in general, and on the pulmonary nerves in particular, in such a way as to produce symptoms of bronchial irritation and dyspnoea, to which bronchial congestion and inflammation were often superadded."

It is certain that localized collapse of the lung often occurs. White and Guitéras attributed the consolidations of the lung to congestive collapse due to enlargement of the tracheal and bronchial glands and "disturbance of the great nervous tract about the root of the lung." They were enabled to satisfy themselves of the existence of glandular enlargement--adenopathie bronchique--in nine of their eighteen cases by percussion practised in the method of M. Geneau de Mussy, who was the first to call attention to the importance of percussing the spinous processes of the vertebræ over the course of the trachea. Following this line in the healthy subject, a distinct tubular (high-pitched and slightly {870} tympanitic) sound is elicited by percussion down to the point of bifurcation of the trachea on the level of the fourth dorsal vertebra. Opposite the fifth and downward we get the lower-pitched pulmonary resonance. When the tracheal and bronchial glands are enlarged, the tubular sound over the upper dorsal vertebræ is replaced by dulness, which may contrast sharply, above with the tracheal, and below with the vesicular resonance.

Some well-recognized peculiarities of the so-called pneumonias of influenza give weight to the view that the consolidations are not, in the beginning, pneumonic at all. Thus, we have at first weakness of the vesicular murmur, then its absence; the respiration soon becomes bronchial, without being preceded by dulness or the crepitant râle; the extension of those consolidations from one part of the lung to another is very irregular; the process is more apt to involve both sides than one; the disappearance of the consolidation is frequently very rapid.

The relations of cause and effect between collapse and catarrhal pneumonia are so close that it is not difficult to see how the condition spoken of may lead to secondary lobular or catarrhal pneumonia. In truth, this is a frequent result of collapse from any cause.

White and Guitéras do not adduce any post-mortem facts in support of their theory. Peacock, however, observed in the epidemic of 1847 softening and enlargement of the bronchial glands in several cases, and in one instance where there was no antecedent disease of the lungs, and where the physical signs corresponded to some extent with those of the cases upon which White and Guitéras base their views.

Gangrene of the lungs must be named as one of the less common complications.

These complications are the chief cause of the danger of influenza in the aged, the debilitated, and those suffering from previous disease of the thoracic organs.

Pleurisy is rare except where there is coexisting inflammation of the lungs. It may be associated with pericarditis. In old persons serous effusions into the pleural sac are now and then encountered.

Troublesome laryngitis and chronic bronchitis may follow the attack. In consequence of the extension of the catarrhal processes along the Eustachian tube an actual inflammation of the middle ear is, in rare instances, set up. Parotitis with salivation sometimes occurs, likewise aphthous inflammations of the mouth.

Herpes labialis occasionally occurs toward the end of the attack; it is then a favorable indication.

Phthisis may be developed in consequence of an attack of influenza, and if phthisis be already established it is apt to run a more rapid course. Emphysematous affections are aggravated; diseases of the heart are unfavorably influenced; chronic nervous affections are made worse, and, in particular, neuralgias are aggravated. Old neuralgias, that have long ceased to give trouble, occasionally reappear during the convalescence.

Persons subject to latent or chronic Bright's disease are especially liable to the more serious manifestations of influenza. The fatal termination of such cases not unfrequently occurs in consequence of an attack.

Many of the older observers speak of the intermittent character of {871} influenza in certain epidemics, and its tendency to run into intermittents, particularly of a certain type, during convalescence. This has not been observed in the outbreaks of later years, and it is probable that in such instances an endemic malaria has modified the epidemic catarrhal fever, or the former has broken out as the latter passed away.

Pregnant women are in danger of aborting.

PATHOLOGY.--Our knowledge of the pathology of influenza is as yet very imperfect. Biermer has described it as the sum of a series of catarrhal manifestations developed under a common epidemic influence. The close association of the various local affections arises from their almost simultaneous occurrence as results of primary pathological processes common to them all. Each of the three groups of symptoms which make up the clinical picture of the disease--namely, the fever, the catarrh, and the symptoms referable to the nervous system--constitutes a distinct factor of influenza, and is a direct outcome of the action of the infecting principle. There is no constant interdependence among these groups, either in the order of their succession or in their intensity. Thus, while all three groups are commonly present from the beginning of the attack, any one of them may be the first to appear or have an intensity out of all proportion to each of the others. The fever is not a result of the catarrhal inflammation, nor are the nervous symptoms the result of both the others. They all spring directly from the action of the same cause.

This view is at variance with the opinion--based upon the fact that ordinary acute local inflammatory diseases, tonsillitis, bronchitis, and the like, sometimes run their course in a similar way to influenza, with fever, nervous depression, and a serious sense of illness--that influenza is a simple epidemic catarrhal inflammation.

The sudden onset of influenza, its not infrequent abrupt termination, which suggests crisis, its unsparing seizure of great numbers of the population, the severity of the nervous symptoms, and the amount of laryngo-bronchial irritation, often out of measure with the lesions of the mucous membranes,--all point to the action of a morbid agent affecting the body at large. The severity of the symptoms also, in many cases, is much greater than in similar acute non-specific local affections, while the complications, and in particular the recrudescence of fading neuralgias and the tendency to abortion, and the sequels, as cough, weakness, headaches, flying pains, which often remain long after convalescence, are evidences of its belonging to the group of infectious diseases rather than to that of simple acute inflammatory diseases.

In conclusion, it must be urged that the similarity of the symptoms in many epidemics, occurring during the course of several centuries and under different social conditions, and even different degrees of civilization, forcibly demonstrates the specific and definite character of the causes which give rise to influenza.

Very little light is thrown upon the pathology of the disease by the anatomical changes found after death. Uncomplicated influenza is rarely fatal. As a rule, the unfavorable termination is due to lung complications. The essential lesions are congestion and catarrhal swelling of the mucous membrane of the upper air-passages and the bronchial tubes. These changes may be restricted, in the lungs, to the trachea and larger {872} bronchi, or they may extend to the finest twigs. They may amount to great thickening and deep capillary injections of the mucous lining of the tubes, which contain clear, frothy mucus or thick, viscid masses of muco-purulent secretion unmixed with air.

More or less congestion of the gastric mucous membrane, and more rarely of that of the intestine, is also met with. The solitary and agminate glands of the intestine are not affected, save as the result of special complications. A few observations relate to the finding of enlarged and softened bronchial glands. More extended researches are needed, not only upon this point, but also in the whole domain of the pathological anatomy of the disease.

Hyperæmia, oedema, hypostatic congestions, splenization, catarrhal pneumonia, and hepatization affect the lung-tissue in cases fatal by the complications which are associated with such changes. The tissue-changes of diseases existing prior to the attack of influenza, such as old consolidations, tubercle, brown induration, emphysema, and so forth, are of course frequently discovered.

DIAGNOSIS.--The discrimination of influenza from other affections having some points of resemblance to it is, under ordinary circumstances, unattended with difficulty. The march of the epidemic, the number of persons attacked, the prominence of the nervous symptoms, the rapidly developed debility, and the character of the cough, usually severe out of proportion to the physical signs, distinguish it from all other epidemic diseases.

It is to be differentiated from non-specific catarrhal affections attended by fever, malaise, weakness, severe headache, and pain in the extremities by a due regard to the causative relations of the two affections. Simple catarrhs not rarely present the group of symptoms which characterize epidemic catarrhal fever, but they occur almost constantly as the result of great and sudden changes in the weather, and are therefore met with in greatest frequency in bad seasons, and are particularly common at the end of winter and in the spring. Influenza is not in any way dependent upon the vicissitudes of the seasons, and may occur, as has been shown, at all times of the year, in wet or dry, mild or cold seasons equally, and in every variety of climate. It is of course diagnosticated without difficulty from the sporadic catarrhal fevers, which lack the characteristic depression, neuralgic and rheumatoid pains, the irritative cough, dyspnoea, and so on.

Cases of influenza are met with that bear a strong resemblance to beginning enteric fever. The malaise, headache, obtunded hearing, mental depression, high fever, coated tongue, tender belly, diarrhoea, are symptoms to be observed in both affections. But influenza lacks the temperature curve, the splenic enlargement, and the eruption of enteric fever, and the progress of the disease will in a few days clear up the most doubtful case.

PROGNOSIS AND MORTALITY.--Death is rare in uncomplicated cases. The very young bear influenza badly; the old bear it more badly still. Nevertheless, children have in some epidemics enjoyed a considerable proportionate immunity. Healthy persons in the middle periods of life bear it well. Certain pre-existing diseases modify its course unfavorably; among these are chronic bronchitis, emphysema, fatty heart, and Bright's disease. {873} The debility of advanced phthisis and other exhausting diseases renders influenza dangerous. Death takes place, in by far the greater number of cases, as the result of the complication of the attack, either by some pre-existing affection or by an acute disease arising in its course. The commonest of the latter are inflammations of the parenchyma of the lungs.

Patients presenting very severe symptoms generally recover if they be not the subjects of complicating maladies or very young or very old.

Relapses are not uncommon; independently of relapses, second attacks have been known to occur during the continuance of an epidemic; it is often the case that an individual in the course of his life passes through several epidemics of influenza, and is the subject of the disease in each of them.