SYMPTOMATOLOGY.—ANALYSIS OF THE SYMPTOMS.—For the purpose of separate consideration it is convenient to take up the symptoms belonging to the fever first, then those of the special catarrh, and finally those more particularly referable to the nervous system; but we encounter in the present state of our knowledge of the pathology of influenza—or our ignorance of its pathology—no little difficulty in deciding under which of these headings particular symptoms are properly to be classed, by reason of the close interdependence of the chief processes of the disease and the anomalies of its phenomena viewed as a whole.
The Fever.—The fever is of the sub-continuous or remittent type, but its range is very irregular. Irregularity of temperature is characteristic of influenza and may assume diagnostic importance.
The intensity of the fever is variable. As a rule, it is moderate or slight; occasionally it is severe. I observed in several cases during the epidemic of 1879 in Philadelphia an evening temperature of only 39° C. (102.2° F.). Da Costa in the same outbreak found the febrile movement not high; the highest temperature he observed was 40° C. (104° F.). Biermer found a temperature of over 39° C. in moderate cases of catarrhal fever, and does not doubt that under certain transient conditions the temperature may reach the height of that of pneumonia or typhus. In weakly persons and the aged the fever is adynamic.
The pulse has no constant characters. Its frequency is moderately increased; it is apt to be less forcible than in health, is generally compressible, sometimes full, often irregular, changing in character in the course of a few hours.
The urine is usually diminished; sometimes its secretion is temporarily suppressed; as a rule, it shows little change, and is rarely, as in other fevers, concentrated and high-colored. It deposits on cooling a sediment of urates, which toward the close of the fever is often very abundant. The defervescence is in many instances attended by a copious secretion of urine. Albumen is not present except as a result of some complication.
At first the skin is hot and dry; later, frequent sweats occur; sweating generally attends the febrile remissions and the defervescence not rarely sets in with copious, acid, ill-smelling sweats. In some cases a tendency to sweat shows itself early and continuous throughout the attack. Sudamina occur in great numbers.
The face is often flushed, and irregular mottlings of the skin, especially upon the neck and chest, have been frequent in some of the epidemics. An outbreak of herpes about the lips is occasionally seen.
Disturbances of the digestive tract are more or less prominent in almost all cases. Only in a rudimentary and sub-febrile form are they absent. In many cases they are such as are usually seen in febrile disorders—namely, loss of appetite, thirst, impaired taste, pasty tongue, tenderness in the epigastrium, and constipation. Nausea and vomiting sometimes usher in the attack. In other cases (the so-called abdominal form) all the above symptoms are more severe, and diarrhoea, colicky pains, and vomiting are superadded. In certain epidemics the intestinal catarrh has shown a tendency to run into dysentery.
The expression of the countenance is changed, in part by the appearance characterizing an ordinary attack of coryza of considerable or great severity, and in part by anxiety and depression. It is pale. Where the pulmonary catarrh is excessive and dyspnoea great the lips become bluish. The facies sometimes suggests that of typhoid fever.
The Catarrh.—A more or less extensive hyperæmia of the mucous membrane of the respiratory tract is invariably present, and may be said to characterize the disease.