Nobody seems to know. I got laid out with a severe case of the flu in 1997. My ex-wife picked it up at the day care she worked at. I developed a high fever and was actually out of work for a few days. I eventually got back to normal, but from that day onward, I was plagued by a persistent, dry barking cough. I let this cough go for 5 months before I finally went to see an MD. He had a chest X-ray done and it came back with "some scarring" but “no mass was detected” (which seemed to be what he was looking for). Still no immediate relief from the barking cough, though.
Within a few more months, the cough seemed to subside a little bit, but in its place was lots of mucus. Now it felt like I had a habitual chest cold 24/7. I eventually went to see a pulmonary doctor who promptly put me on Tequin and diagnosed me with acute bronchitis. The antibiotic did no good. A few months later I saw him again whereupon he diagnosed me with COPD (more like chronic obstructive bronchitis in my case).
Now I am in pretty bad shape. I cannot seem to shake this new round of infections, and the future looks pretty grim to me right about now.
I don't know what I did to make this all happen to me. I only smoked for a couple of years when I was in high school. I am 50 years old now (I was 40 when first diagnosed). I worked on a radial arm saw in a lumber yard for a couple of years but never with any chemicals or asbestos or anything like that. My current wife is a nurse's aide and seems to think I must have developed some type of strep infection immediately after my bout with the flu, which led to the lung scarring (since I didn't go to see a doctor right away).
I read of another case similar to mine in a pulmonary magazine some years ago. The guy was writing in with the same type of disbelief. He had the flu in 1997 and it ended up giving him COPD. Another non-smoker as well. My wife also knew a lady in her hospital whose daughter lost all kidney function after catching the flu in that same year. A really killer, it seems to have been.
I guess it really doesn't matter now, but I would still like to know just what did happen to me. Maybe others with persistent coughs will one day read this and not hesitate to seek out professional help.