Medical officials say more than 2,700 cases of dengue fever have been reported in India, with at least 40 deaths.

Most of the cases have occurred in Delhi and Kerala, including Prime Minister Manmohan Singh's two grandsons -- Rohan, 11, and Madhav, 17. Both boys and a son-in-law have been admitted to the All India Institute of Medical Sciences in New Delhi, the Press Trust of India reported Wednesday.

Dengue fever is a mosquito-borne infectious disease found in most tropical and subtropical areas and is characterized by rash, severe frontal headaches, high fever, joint and muscle pain and often nausea and vomiting and even brain hemorrhages.

Indian officials continued to urge calm. Health Minister Ambumani Ramadoss told PTI: "There is no need to panic and harbor apprehensions. We have a problem and it is a matter of concern. It is not an epidemic."

Copyright 2006 by United Press International