FRIDAY, March 1, 2002 (HealthDayNews) -- Walking pneumonia is supposed to be a temporary disease, here today and gone tomorrow or maybe next week. But one strain apparently missed the memo, according to researchers who think it may leave behind germs that could spawn asthma.
In tests at the University of Texas Southwestern Medical Center, mice infected with a mild form of pneumonia turned up with symptoms of wheezing, suggesting that they developed asthma, said Dr. R. Doug Hardy, an assistant professor of internal medicine.
"What this does for humans is provide more evidence that persistence of [pneumonia] organisms in their lungs can make their asthma worse or even cause it in people," Hardy said.
Pneumonia is a fairly common and occasionally fatal infection that often strikes hardest at the elderly. In pneumonia, the lungs become inflamed and swell, said Dr. Kevin Glynn, a lung doctor -- known as a pulmonologist -- at Scripps Mercy Hospital in San Diego.
When pneumonia strikes, the lungs become like a "wet sponge," Glynn said. "You can imagine it's harder to breathe through a wet sponge than a dry sponge."
Both viruses and bacteria can cause pneumonia, as can a kind of germ known as a mycoplasma that fits into neither category. Mycoplasma germs can cause "walking pneumonia," an informal term that refers to milder forms of pneumonia that don't limit patients to bed rest.
Few people die from mycoplasma pneumonia, which mainly strikes children and young adults, according to the American Lung Association.
Doctors know that some patients with mycoplasma pneumonia sometimes go on to develop asthma symptoms, Hardy said. Researchers at the University of Texas decided to study the phenomenon by infecting mice with the disease. The study findings appear in the February issue of Infection and Immunity.
Even though the mice recovered and their lung inflammation went away, the germs remained in the lungs of 70 percent of the mice for three months. The germs were still there in 22 percent of the mice 18 months later.
"It's not something that goes away quickly," Hardy said. Experts aren't sure why mycoplasma germs are so tough to eradicate, he said.
After 18 months, some of the mice developed bronchial problems that are similar to those that affect people with asthma.
Researchers aren't sure why some mice developed asthma-like symptoms while others didn't.
The study results may help people with asthma, Glynn said, by encouraging the use of drugs that kill microplasma infections.
"It might make a physician more alert, more likely use a microplasma agent more quickly," he said.
But Glynn said the findings probably won't change the way he treats people with walking pneumonia.
What To Do: These Web pages from the American Lung Association offer a general primer on pneumonia. Learn about children and walking pneumonia in this primer from Allkids.org.
