Convalescence is apt to be protracted, being especially characterized by malaise and nervous depression, practically neurasthenia.
Leucopenia and polymorphonuclear percentage reduction appear by the second day.
Clinical Types.—In different epidemics it is noted that some one clinical feature may seem outstanding. Of these we may note:—
(1) The pulse rate is slow for the temperature rise, thus reproducing a phenomenon common in yellow fever (Faget’s law). It is in recent epidemics particularly that clinical descriptions have recorded the frequency of a very slow pulse, most of the older authorities having noted a pulse rate which corresponded to the elevation of temperature.
(2) In some epidemics the feature of glandular swelling is prominent, while in others the swelling is so slight as to be overlooked.
(3) The characteristic “saddle-back” temperature chart seems lacking in the general run of cases in certain outbreaks. It is possible that such epidemics, showing atypical temperature curves, may have been due to phlebotomus fever, or seven-day fever, instead of dengue.
(4) In some epidemics, the rash is insignificant or very slight in most cases. This observation is possibly dependent on the ephemeral character of the eruption in certain groups of cases.
(5) From the chart Fig. 138, analyzing the symptoms in one epidemic, it will be noted that Lane observed cold, clammy, dusky extremities in 17 per cent of his cases. This is an unusual finding.
Symptoms in Detail
Onset and the Temperature Chart.—Dengue probably sets in more abruptly than any other disease. The temperature chart is typically saddle-back.