CHAPTER ONE INTRODUCTION 1.1 Background of the study Dengue is an arbovirus disease complex which includes dengue fever (DF) and dengue hemorrhagic fever (DHF) and its subsequent dengue shock syndrome (DSS). It is caused by four serotypes of dengue virus. A dengue virus infection may be asymptomatic or it may lead to undifferentiated viral fever syndrome, dengue fever, fever hemorrhagic fever or dengue shock syndrome. (World Health Organization 2003) The disease is often, though not exclusively