Some cases of human obesity may well be caused by a virus, say Nikhil Dhurandhar and Richard Atkinson of the University of Wisconsin, Madison. The researchers analysed the blood of 199 volunteers for anti- bodies for the adenovirus Ad-36, that causes obesity in animal models. Volunteers included 45 lean people while the remaining 154 were obese. While all the lean people were seronegative, (did not have antibodies to Ad-36), 23 of the Obese people were found to be seropositive and responded significantly better to treatment with obesity drugs than those who were seronegative (The Lancet, Vol 349, No 9049).