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.