Nalini Ravichandran | ENS The mystery fever that afflicted hundreds across Tamil Nadu has been reported to be a `mixed fever' -- chikungunya and dengue -- spread Health dept figures show 1,250 cases of chikungunya, 500 cases of dengue and 600 cases of malaria in the last six months THE mystery behind the unidentified fever that had baffled the Tamil Nadu Health department for some time now, has been cracked with the Centre's report stating that it is nothing but a `mixed fever' - chikungunya and dengue - spread by mosquitoes. T h e r e w a s n o mystery behind the fever, Health Secretary V K Subburaj said, adding that its spread could be checked if the mosquito menace was controlled. He also attributed the dis- ease's spread to adverse weather con- ditions in the State. Two teams from the National Institute of Communicable Diseases, New Delhi, and the National Institute of Virology , Pune, were in Tamil Nadu last month to determine the cause of the fever that has affected hundreds across the State. They took 80 samples from patients in Madurai and Tirunelveli for analysis. The Centre's report is believed to state that surroundings need to be kept clean.