The monsoon nightmare is back to haunt Jamshedpur and its neighbours. The East Singhbhum civil surgeon's office on Tuesday issued a double alert for dengue and Japanese encephalitis in the steel city after 18 suspected cases of the vector-borne diseases were reported from Tata Main Hospital (TMH) on Monday. "A general alert has been sounded to all hospitals, nursing homes and health centres in and around Jamshedpur. We have to maintain strict vigil," said civil surgeon Dr S.K. Jha. Sahir Pall, district officer for the Centre's Integrated Disease Surveillance Programme (IDSP), said the private hospital had reported 14 dengue and four Japanese encephalitis suspects. "Blood serum samples have been sent to the microbiology department of MGM Medical College in Dimna for confirmation. Reports are expected in another 48 hours," Pall added. Sources at TMH said all the four encephalitis suspects were children - three boys and a girl aged between four and 12 years. Among the patients with dengue-like symptoms are a seven-year-old boy and a 57-year-old man. The rest - six men and six women - are in their middle ages. "The patients have come from various parts of Jamshedpur like Birsanagar, Sakchi, Sonari, Kadma, Mango and Bagbera as well as Adityapur in adjoining Seraikela-Kharsawan district. Three of the suspects also hail from Barbil in Odisha," said a source. While the bite of the Aedes aegypti mosquito causes dengue fever, Japanese encephalitis is transmitted to humans through infected Culex mosquitoes, particularly the Culex tritaeniorhynchus. In 2015, 23 blood serum samples of suspected dengue patients were sent to the microbiology department of MGM for IgM ELISA test. Ten had tested positive. Of the 200-plus samples tested for Japanese encephalitis the same year, 40 had confirmed presence of the JE virus. While no case of dengue or Japanese encephalitis was reported in 2014, the incidence of dengue was high in 2013 and 2012, with 27 and 46 testing positive in these years, respectively. In 2011, nine confirmed dengue cases had been reported in the district. The civil surgeon's office, once again on Tuesday, prodded Jamshedpur Notified Area Committee, Mango Notified Area Committee, Jugsalai Municipality and Jusco to increase frequency of fogging, sprinkling of bleaching powder, spraying of larvicides and other disinfectants in areas under their command. It also issued a notice to all government and private hospitals/nursing homes, asking them to report suspected cases within 24 hours.