The cases of vector-borne diseases are usually reported between mid-July and November-end, but this period may stretch up to mid-December.
Links:
[1] http://admin.indiaenvironmentportal.org.in/news/8-cases-malaria-mosquito-breeding-found-over-14300-households-delhi
[2] http://admin.indiaenvironmentportal.org.in/category/newspaper/financial-express-new-delhi
[3] http://admin.indiaenvironmentportal.org.in/category/thesaurus/delhi
[4] http://admin.indiaenvironmentportal.org.in/category/thesaurus/vector-borne-diseases
[5] http://admin.indiaenvironmentportal.org.in/category/thesaurus/malaria
[6] http://admin.indiaenvironmentportal.org.in/category/thesaurus/dengue
[7] http://admin.indiaenvironmentportal.org.in/category/thesaurus/chikungunya
[8] http://admin.indiaenvironmentportal.org.in/category/thesaurus/health