Researchers already know that ten different viruses can cause obesity in animals. Recent information presented at a conference in Boston by Dr. Nikhil Dhurandhar and colleagues, pin-points adenovirus-36 as a potential cause of obesity in humans. In the latest studies these researchers were able to convert human stem cells into fat cells by infecting them with the adenovirus. By converting human stem cells into fat (adipose) cells adenovirus-36 can cause an increase in the amount of fat tissue in the body. The adenovirus is a common infection in infants and children causing flu like symptoms of sore throat, runny nose, cough, diarrhea and fever. Pink-eye (conjunctivitis) can also be caused by adenovirus. Once a cell is converted to a fat cell by the virus it may remain in that form for its entire existence.

Studies in which humans have been infected with adenovirus-36 have not been conducted although it was found that 30% of people with evidence of prior infection with adenovirus-36 were obese.

Studies implicating viral infection as a contributor to obesity raise the question if a vaccine against the culprit viruses could be developed in the future. If successful vaccination might then be a way to help people protect themselves against developing obesity. The researchers point out that although viruses might increase fat cells in the body, a lifestyle of over consumption of calories or sedentary lifestyle is also needed to complete the conversion to obesity.