Dengue (DENV) and West Nile (WNV) viruses are arthropod-borne viruses that are able to emerge or re-emerge in many regions due to climatic changes and increase in travel. Since these viruses produce similar clinical signs it is important for physicians and epidemiologists to differentiate them rapidly. A molecular method for the detection and quantitation of these viruses in serum samples was carried out using One-Step Real Time RT-PCR technique. The technique enables the early diagnosis of the two Arboviruses during viremia, including cases of co-infection. This book will serve as a guide to undergraduate students and researchers.