Of the 1372 dengue cases, 897 (65%) were classified as primary dengue and 475 (35%) as secondarydengue cases. However, the proportion varied widely geographically, with Theni, Tamil Nadu; Tirupati, Andhra Pradesh and Udupi-Manipal, Karnataka reporting more than 65 per cent secondarydengue cases while Srinagar, Jammu and Kashmir reporting as low as 10 per cent of the same. The median age of primary dengue cases was 25 yr [interquartile range (IQR 17-35] while that of secondarydengue cases was 23 yr (IQR 13.5-34). Secondarydengue was around 50 per cent among the childrenbelonging to the age group 6-10 yr while it ranged between 20-43 per cent among other age groups. Interpretation &
conclusions:
Our findings showed a wide geographical variation in the distribution of primary and secondarydengue cases in India. It would prove beneficial to include primary and secondarydengue differentiation protocol in the national denguesurveillance programme.