In California it may be the summer of fires as smoke fills the air, but at Yale researchers pump smoke into the lungs of mice in order to help find an explanation behind reactions in smokers due viral infections.

Recent studies by researchers at Yale found that people who smoke have a worse reaction to viral infections not due to a weakened immune system, but because of an overreaction.

The study published in the August 2008 edition of the “Journal of Clinical Investigation,” answers the question about why viruses that don’t have a serious reaction in non-smokers affect smokers so seriously. While the most common explanation had to do with a weakened immune system studies prove otherwise.

By exposing mice to smoke equivalent to two cigarettes a day, researchers including Dr. Jack A. Elias, Dr. Min-Jong Kang and Medical Professor at Yale School of Medicine Waldermar Von Zedtwitz found that when exposed to a flu-like virus the mice cleaned the illness out of their system normally, but had accentuated tissue damage that experts labeled as an overreaction.

The viral infected mice displaying inflamed and heavily damaged tissues put evidence behind the occurrence that more smokers die from influenza and chronic obstructive pulmonary disease than anyone else. The findings also provide answers behind why children exposed to second-hand smoke are more prone to respiratory viral infections, which guides the way to a cure.

“It's like smokers are using the equivalent of a sledge hammer, rather than a fly swatter, to get rid of a fly," said Elias who describes the findings metaphorically. "The anti-viral responses in the cigarette smoke exposed mice were not only not defective, but were hyperactive."

The reaction, or “overreaction,” as Elias calls it may have been displayed in mice, but the next, larger step is to find the same thing in humans. After the proof in people, a plan of prevention can be implemented.

"If the exaggerated responses are verified in human studies, it will be the first explanation for why viral infections are more serious in smokers. Once verified, we can find ways to prevent the destruction of lung tissue and the higher illness and death among smokers," Elias said.

James P. Kiley who is the director of the Division of Lung Diseases of the National Heart, Lung, and Blood Institute, affirms the optimistic trail that Yale researchers have thus paved. "These studies have identified molecular pathways that can explain how cigarette smoke exposure and viral infections interact to make breathing problems worse in diseases like chronic obstructive pulmonary disease," he said.