Dengue refers to a tropical disease caused by four different types of virus. It is usually transmitted by mosquitoes and the common symptoms include fever, headache, muscle and joint pains and skin rash. There is no vaccine for dengue and the only way to reduce infections is to improve hygiene levels so as to prevent mosquito-bites and prevent mosquitoes from breeding. It’s particularly difficult to create a vaccine because it’s caused by different viruses and there are no animal models available for testing. The disease kills over five thousand Indians every year and is a seasonal threat, particularly during the monsoon seasons.