Dengue Epidemiology

Which of the following is the primary vector for dengue transmission in India?

During a dengue outbreak investigation in a coastal town in Tamil Nadu, epidemiologists identify that 60% of symptomatic dengue cases occur in children aged 5–14 years, while 35% occur in adults aged 25–45 years, and only 5% in elderly (>60 years). Serological surveys show that 85% of the elderly population have dengue-specific IgG antibodies, compared to 40% in the 25–45 age group and 15% in children. What does this age-stratified seroprevalence pattern most likely indicate about the dengue epidemiology in this town?

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?

What is the typical incubation period of dengue fever in an infected individual?

A 32-year-old woman from Chennai presents on day 4 of fever with severe myalgia, headache, and a maculopapular rash over trunk and extremities. She has thrombocytopenia (platelets 80,000/μL) and haemoconcentration. Which investigation is most appropriate to confirm dengue virus infection at this stage?