Several people are also under treatment for the disease at various private and government hospitals, they said.
Alarmed over the dengue cases the health directorate has issued directives to respective chief medical officers to undertake fogging and sprinkling of insecticides.
The health department officials have been asked to collect information about dengue patients in different parts of the state and take prompt action to control the situation, sources said.
About 40 cases have come to light in Lucknow, Agra, Ambedkarnagar, Hardoi and Saharanpur districts and steps have been initiated to control the situation, they said.
Medicines have been provided at all the primary health centres and community health centres, and control rooms were also being set up at district level government hospitals, they said.
People are being aprised of the various precautions needed to be taken to check the disease and asked to consult doctors instead of going in for self treatment, sources added.