Dengue: current trends and challenges--an Indian perspective.

INTRODUCTION Dengue is caused by four flavivirus serotypes (DEN-1, DEN-2, DEN-3 and DEN-4). The incidence of dengue fever (DF) and dengue hemorrhagic fever (DHF) has increased thirty-fold globally in the last four decades and more than half the world’s population (including developed countries) is now threatened with infection from dengue virus. Epidemiological evidence shows that DHF and dengue shock syndrome (DSS), the more serious manifestations of the disease, occur more frequently on re-infection with a second serotype. The co-circulation of multiple serotypes has also been reported from many countries. The situation in India is reflected by the occurrence of major disease outbreaks in India from time to time over the last few decades. However, no reliable data are available to assess the magnitude of the disease in our country. But, obviously, the situation is not very encouraging. In the last seven years, there have been two major disease outbreaks of dengue in north India.