How frequently do you encounter 'Dengue-like-illness' in your practice, and how often do you investigate it further?

Pediatric patients have been presented to me many a time with low platelet counts, low total counts, mild to moderate elevation of PCV, and hypotension. Surprisingly, the symptomatology and presentation is not as severe as that of Dengue, and recovery is rapid. Frequently there is evidence of a capillary leak. I ran the sero-testing for Dengue (including NS-1, IgM, IgG), Widal, MP, IFA (Chikungunya), and blood cultures however, all of these turn out to be negative.
Management line is the same as with Dengue- with Fluid support.
Are we dealing with a 'shift' in the dengue virus in Asia?.