Dengueis the most important vector borne viral infection worldwide with estimated 2.
5billion people at risk, according to the World Health Organization (WHO) 1.The number of cases and number of countries affected has doubled from theperiod 1990-1994 to 2000-2004 2&3. However, the recent report estimated athree times increased disease burden of dengue than the earlier report of WHO i.e., 390 million infections occurs peryear. India alone estimated to contribute 33 million dengue cases of the totalestimate of the global dengue disease burden per year 4. Larger epidemics arebecoming more common 4, with countries in Asia witnessing an increase insevere dengue and a higher mortality in the earlier stages of the infection5.
Dengue, though it has been known as an important public health problem inIndia, the recent escalating trend of its unexpected emergence/spread in Indiansubcontinent stresses for adequate preparedness to prevent and control itsfurther spread. Moreover, the non-availability of a commercial vaccine andspecific treatment strategies may further worsen the situation and warrantsimmediate reviewing of the existing surveillance mechanisms. Critical assessinghelps to identify and evolve strategies to fill up knowledge gaps could resultsin effectively prevent impending outbreak. WHO World Health Assembly urgedmember states to improve surveillance, prevention, control and management ofDengue 6&7. Thealarming increasing trend of dengue cases and deaths due to dengue from 2007-2012 in India has been shown in figure.1. The un-usualemergence of certain dengue virus strains with epidemic potential such asdengue virus-4 (Serotype I) Dash et al2011) and dengue virus-3 (Serotype III) Kumar et al 2010) in India indicate the necessity of continuousmonitoring of the viruses. The circulation of multiple serotype with increasedgenetic diversity among each serotype has been shown to be resulted in alteringtransmissibility, virulence and antigenicity (Zhang et al 2012).
In addition, the existence of dengue virus variant orvirulent genotype has also been proved to be co-related with disease severity(Chakravarti et al 2012) despite thedata on the existence of dengue virus co- circulation and dengue virusquasispecies (Takeshi Kurosu, 2011) in vector is not available which is veryvital and have epidemiological significance. Surveillanceis considered as the important component of dengue prevention and controlprogrammes. The effective surveillance system enable to assesses the risk and results inmonitoring epidemic response and evaluation of the ongoing programme. Thoughroutine surveillance includes the rapid detection of human infection and vectorsurveillance along with the ecological and sociological risk factors, viralsurveillance will give us information about the invasion of a new or re-introduction of a long time absent serotype inthe area. Early detection of dengue virus in essentially required as a delay invector control activities caused by prolonged laboratory confirmation maycontribute dramatically to increased dengue incidence and geographic viralspread WHO;2012.