The stomach and intestines contain disintegrated blood. Petechiae and erosions are common in the cardiac end of the stomach. The upper part of the duodenum shows changes similar to those seen in the stomach but the other portions of the intestines are essentially negative.
The spleen does not show any particular change. The kidneys are enlarged, congested and on microscopical examination show fatty degeneration of the renal epithelium.
The adrenals often show fatty degeneration, especially of the cortex.
Haemorrhagic infiltrations are marked features in skin and mucous and serous membranes.
Symptomatology
A Typical Case. Sthenic Stage.—With very slight or absent prodromata, often during the night, the disease sets in rather abruptly with chilly sensations and the temperature rapidly rises to about 104°F. The face is flushed, dusky and swollen, the eyes injected. Very severe frontal and orbital headaches with marked rachialgia of the lumbo-dorsal region are peculiarly characteristic. The pulse is of high tension and the rate from 90 to 110. The systolic pressure is increased—at times as high as 175. These are the early manifestations of the first or sthenic period of the disease.
Vomiting, first of mucus and bile, comes on very early. About the second day albumin appears in the urine and by the 3d or 4th day this is present in large amount and is associated with the presence of hyaline and granular casts. The temperature remains fairly high for three or four days, with morning remissions and evening exacerbations. Of great diagnostic value is Faget’s law as to lack of correlation of temperature and pulse, in that by the 2d day, notwithstanding the high temperature, the pulse rate becomes less and by the 3d or 4th day it has probably decreased 20 to 40 beats from its initial rate.
Stage of Remission.—About the close of the 3rd day or upon the 4th day there may occur a fall in the temperature and a decided amelioration of the symptoms. This however is frequently not noted and even when present may last only for a few hours. It is often called the stage of remission or calm. By the 3d day the congestion of the facies and other sthenic manifestations have disappeared and, possibly preceded by the short period of remission, there is ushered in the second or asthenic stage.
Asthenic Stage.—It is at this time that we have the appearance of the most characteristic features of yellow fever—the jaundice and the haemorrhages. The jaundice is first noted in the sclerotics and rapidly spreads over the body as a lemon to orange yellow tinging. Swelling and bleeding of the gums are the earliest signs of the damage to the capillaries. This may go on to bleeding from the nasal mucosa, the intestines and, best known and most dreaded, the coffee ground vomiting or black vomit of gastric haemorrhage. Epigastric tenderness is often marked. In very severe cases haemorrhagic extravasation into the skin may appear. The mind is peculiarly clear, the patient alert and suspicious. At times patients may be delirious even to the extent of wild struggling to throw themselves out of bed.
In favorable cases the temperature rapidly falls to normal, associated with an unusually slow pulse rate, even below 45.