In the first few days there is a normal white count, with an increase in the percentage of the polymorphonuclears and later on an increase in the large mononuclears.
Fig. 46.—Temperature chart from one of the experimental yellow fever cases reported by the U. S. Army Yellow Fever Commission. A severe case with recovery.
Besides the typical course we may have cases so mild that the albuminuria is insignificant and the jaundice and haemorrhages entirely absent. On the other hand we may have fulminating cases with jaundice and black vomit setting in by the end of the 3rd day and rapidly going on to a fatal termination.
Symptoms in Detail
The Temperature.—This rises abruptly, reaching its maximum by the 1st day. Very high temperatures are not a feature of yellow fever. There is nothing characteristic in the further course of the fever chart and it should be borne in mind that the so-called intermission is transient and deceitful.
General Appearance.—On the 1st day the face is swollen and congested. This florid congestion, which may extend down the neck to the upper part of the chest, is more marked in yellow fever than in any other disease. The eyes are shining, the conjunctivae injected and there is photophobia.
About the end of the 2d day the facial congestion disappears to be succeeded by an earthy tinging and subicteroid tinting of the conjunctivae. The jaundice does not appear until about the fourth day. This may be noted somewhat earlier if one blanches the skin by pressure with a glass slide. Petechial eruptions may be prominent in the later stages. The jaundice is best seen at a distance of 5 to 6 feet.
The Circulatory System.—Of peculiar value in diagnosis is Faget’s law—a falling pulse rate with constant temperature or a constant pulse rate with a rising temperature.
A markedly slow pulse, between 40 and 50, is often recorded about the time of the period of remission.