Kinetics of changes of Histamine throughout the course of
illness
In order to determine the changes in urinary histamine throughout the
illness, we measured histamine in 16 patients DF and 16 patients with
DHF throughout the course of illness (Fig 7a) . In patients with
both DF and in those who proceeded to develop DHF, urinary histamine
levels gradually declined from illness day 3 onwards. We also
investigated possible diurnal variation in urinary histamine levels in 9
patients with DF and 7 patients with DHF (Fig 7b) . In patients
with both DF (p = 0.004) and DHF (p = 0.01) the urinary histamine levels
significantly decreased in the afternoon (3pm) samples compared to the
morning samples, although there was wide inter-individual variation(Fig 7b). Similar diurnal variations were seen with serum viral
loads in patients with both DF and DHF (Fig 7c ).