Health Department sources said 25 districts are under the grip of the vector-borne disease barring Sambalpur, Malkangiri, Koraput, Gajapati and Bargarh districts.Keonjhar tops the chart of dengue-affected districts with 1,200 positive cases, followed by Cuttack with 1,129 cases, Ganjam (113), Jajpur (83), Bhadrak (72), Jagatsinghpur (65), Kendrapara (56), Puri and Khurda with 48 cases each. On Sunday, 97 fresh cases were detected in the State which include 51 from Cuttack alone besides 15 positive cases from Keonjhar. The industrial areas of Jagatpur in Cuttack and mining belt of Barbil have recorded close to 2,000 positive cases. Meanwhile, the worst-hit districts have been asked to monitor the health condition and fever of people who are coming from metros and other dengue-hit States. Health officials have also been told to conduct door-to-door fever surveillance and civic officials asked to intensify fogging activities.