Following the death of Tasneem Jafri, 4, and tariq Jafri, 32, two boys from Malwani Mhada colonies were suspected with dengue and admitted to Kokilaben Dhirubhai Ambani Hospital in Andheri on Tuesday.
Brothers Mohammed Faiz, 17 and Mohammed Faiz Idris, 15, were admitted after their condition worsened at a private clinic.
"The elder brother had tested positive for dengue, but the younger was negative," said Dr Mangala Gomare, chief epidemologist, BMC.