Obesity not only makes flu more severe, but also lengthens the period of viral shedding for influenza A, according to a study by University of Michigan researchers, partly funded by the National Institute of Allergy and Infectious Diseases.
Over 3 flu seasons, the researchers monitored 1,783 people from 320 households in Managua, Nicaragua. During that time, 87 people became ill with influenza A and 58 with influenza B.
More than 40% of the adults aged > 18 years were obese, as defined by body mass. Obese adults with ≥ 2 symptoms of influenza A (n = 62) shed the virus 42% longer than did nonobese adults, or 5.2 days compared with 3.7 days, respectively. Obese adults with 1 or no symptoms of influenza A (n = 25) shed the virus 104% longer than nonobese adults—3.2 days compared with 1.6 days, respectively.
Obesity was not a risk factor for increased viral shedding duration in children aged 5 to 17 years or for adults with influenza B.
The researchers suggest that chronic inflammation caused by obesity may be responsible for the increased viral shedding. Reducing obesity rates could be an important target to limit the spread of viral infectious diseases, they suggest. The findings may have particular significance in the US, where in 2014 35% of adults were obese compared with 17.4% of adults in Nicaragua.