A 28-year-old woman from Mumbai presents with sudden onset fever, severe headache, and myalgia for 3 days. On examination, she has a maculopapular rash sparing palms and soles, and a positive tourniquet test. Her platelet count is 95,000/μL and haematocrit is 38%. She reports that her 5-year-old son had similar symptoms 2 weeks ago, which resolved completely. What is the most likely diagnosis and what is the epidemiological significance of her presentation?