Heavy Alcohol Use May Increase Severe Influenza Risks
Alcohol and Influenza Risk
Heavy alcohol use for four weeks -- the human equivalent of seven beers or glasses of wine per day -- caused mice infected with the influenza virus to have more severe illness and higher death rates than similar mice that were not given alcohol.
The results suggests that chronic, heavy alcohol use may increase the risk for severe influenza respiratory disease, said David Meyerholz, D.V.M., Ph.D, assistant professor of pathology in the University of Iowa Roy J. and Lucille A. Carver College of Medicine.
Meyerholz presented the finding -- part of a larger, ongoing study of the effects of chronic alcohol exposure on the immune system -- April 28 at Experimental Biology 2007 in Washington, D.C. His presentation was part of the scientific program of the American Society for Investigative Pathology.
In humans, excessive and chronic alcohol consumption has been linked with alterations in the immune response, including reduced capacity to fight infection. Chronic alcoholics are recognized clinically to be more susceptible to community-acquired pneumonia as well. The UI scientists wanted to find out if chronic alcohol consumption changed the body's immune response to influenza infection -- a question of increasing importance in light of concerns over emerging influenza viruses.
In this study, the scientists added ethanol to the drinking water of mice. The mixture of one-fifth alcohol to four-fifths water mimics heavy drinking in a human. After four weeks of consuming the water/alcohol mix, the mice were infected with influenza. Mice with no history of alcohol use also were infected with the virus. Because of the strength of the viral dose, all the infected mice developed necrotizing bronchiolitis (inflammation and tissue death in the smallest air passage of the lungs). However, by day five, these changes were more pronounced in mice that had consumed alcohol. The alcohol-using mice also began to show more widespread and more severe lesions in the lungs, including pooling of fluid and extensive white blood cells in the airways sufficient to inhibit breathing. These mice also were more likely to lose weight, have other signs of illness and have increased mortality, compared to the water-drinking controls.
After looking at the possibility that chronic alcohol exposure might increase the presence of the influenza virus in the body, Meyerholz's team concluded that the study findings suggest that heavy alcohol use alters the immune system's ability to control the virus, predisposing the lungs to increased damage such as that seen in the alcohol-using mice.
Studies are now being conducted at the UI Carver College of Medicine to further define the immune system deficiencies associated with chronic alcohol exposure and how that affects the severity of influenza disease.
Meyerholz's co-authors on the study that was presented at Experimental Biology 2007 are: Michelle Edsen and Ruth Coleman, research assistants; Robert T. Cook, M.D., Ph.D., UI professor of pathology; and Kevin L. Legge, Ph.D., UI assistant professor of pathology. The study was supported in part by the National Institutes of Health and the UI Department of Pathology.