Dengue fever is a mosquito borne illness prevalent in Southeast Asia, Latin America & Africa. It is caused by the bite of infected Aedes mosquito. There are 4 types of Dengue viruses and all of them can cause disease. Symptoms are like flu resulting in fever, headache & muscle pain. Later on a rash may also appear. Severe infection can cause bleeding & you may go into shock. Detection of NS1 antigen is associated with a higher risk of developing severe illness specially if positive beyond 5th day of fever. This is a rapid test for the detection of NS1 antigen.