Delhi hospitals have reported 59 cases of malaria during the week ending on July 29, according to the weekly report released by the municipal corporation of Delhi (MCD) on Monday. This takes the total number of malaria cases reported this year till July 29 to 304.Of the 304 cases, 150 people who had malaria were residents of Delhi; the rest came from neighbouring states for treatment in the Capital. The number of malaria cases reported so far this year is 46 more than the number of malaria cases that had been reported during the same period last year.The reason for higher incidence could be the cyclic trend of vector-borne diseases, say experts. “For the last few years, the number of cases of malaria had gone down significantly, meaning the immunity to malaria because of the presence of the plasmodium, which causes malaria, must also have gone down. This leaves the population susceptible to the disease,” said Dr DK Seth, a municipal health official.No deaths due to the disease have, however, been reported by the three MCDs so far. Last year, around 17 suspected malaria deaths had been reported by the corporations.Malaria is a mosquito-borne disease caused by the plasmodium parasite. It causes fever, chills and sweating, shivering and fatigue. Unlike dengue and chikungunya that are transmitted by the day biting Aedes aegypti mosquito, malaria is spread by Anopheles mosquito.“The higher number of cases cannot be attributed to the type of vector control measures as breeding prevention measures are the same for Aedes and Anopheles mosquitoes. The only difference is that Anopheles mosquitoes can breed in any water while the Aedes mosquitoes need clean, stagnant water,” said Dr Seth.The report also recorded 57 cases of dengue, taking the total to 237 cases this year so far. No dengue deaths either have been reported by the corporation so far, though, two deaths related to dengue have been reported by two city hospitals.Twenty-five cases of chikungunya were also reported by the corporation during the week ending on July 29, taking the total number of chikungunya cases to 220. Last year, Delhi had a chikungunya outbreak, which saw a total of 7,760 cases of the disease being recorded. However, only one case of chikungunya has been reported in Delhi till July end last year.