Acute viral infection does not appear to be a primary cause of acute exacerbation of idiopathic pulmonary fibrosis (IPF), a progressive, deadly disease resulting in thickening and scarring of the lungs, according to a study conducted by researchers from the U.S., Korea and Japan.

Previous studies had suggested viral infection might cause exacerbation of IPF in a majority of patients who have the condition, which occurs most often in people between 50 and 70 years of age...