system
Medical AI Inquiry: You were designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.
user
Dengue hemorrhagic fever is caused by ?
assistant
The correct answer is  Ans. is `d' i.e., Infection with more than one dengue virus DENGUE FEVER Dengue fever is caused by arboviruses (at least 4 serotypes have been recognized) It is transmitted by Aedes (Aedes aegypti is the main vector). The reservoir of infection is both man and mosquito. The transmission cycle is Man-mosquito-man Dengue fever occurs both epidemically and endemically. Epidemics stas in rainy season and are usually explosive. Aedes mosquito becomes infective by feeding on a patient from the day before onset to the 5th day of illness.