Dengue fever is the most common of all arthropod-borne viral diseases and has emerged as a major public health problem in recent years. Though the disease has been referred in ancient Chinese medical encyclopedia, the first case was reported in 1789 during the epidemics in Asia, Africa and North America. It was then when Benjamin Rush coined the term ‘break bone fever’ because of the symptoms of myalgia and arthralgia. However, the term dengue fever came into general use only after 1828 (Anonymous, 2010) .
Dengue viruses (DENVs) belong to family Flaviviridae, which are transmitted through mosquito; Aedes aegypti and also by Ae. albopictus. There are four sero types of the virus referred to as DENV-1, DENV-2, DENV-3 and DENV-4, actually originated in monkeys and independently jumped to humans in Africa or Southeast Asia between 800 and 100 years ago (Brett et al. 2007) . Each dengue virus is an encapsulated RNA virus and is composed of three structural protein genes, which encode the nucleocapsid or core (C) protein, a membrane-associated protein, an enveloped (E) glycoprotein and seven non-structural (NS) proteins (Chaturvedi et al. 2005) [23, 24, 25, 26, 27, 28, 45, 94]. All four strains are capable of causing three spectra of disease – Dengue fever (DF), Dengue Haemorrhagic Fever (DHF) and Dengue Shock Syndrome (DSS) (David et al. 2010; Gupta et al.2012) [8, 34, 39, 44, 45].
Today, about 2.5 billion people live in areas where, there is a risk of dengue transmission. It is endemic in over 100 countries in Asia, the Pacific, the Americas, Africa, and the Caribbean. The World Health Organization (WHO) estimates that 50 to 100 million infections occur each year, including 500,000 DHF cases and 22,000 deaths, mostly affecting children (Brett et al. 2007) .
In India, the first confirmed case reports of dengue dates back in the year 1940. Since then many cases have been reported from various states (Gupta et al.2012) [8, 34, 44, 45]. The first major wide spread epidemics of DHF/DSS occurred in India in 1996 involving areas around Delhi and Lucknow and then it spreaded to all over the country (Anonymous, 2010) .