Asthma is becoming more common in developed countries, but no one knows exactly why. Researchers are sure of one thing, though: A child is most likely to develop asthma if there's a family history of allergies and asthma. And now a new study suggests that kids also might be at increased risk of getting the common chronic disease of the lungs because of something else that parents don't have much control over — kids' birthdays.
Looking at more than 95,000 infants born from 1995 to 2000, researchers followed the children through 2005. What they found: Those born in the autumn were nearly 30% more likely to get asthma. The researchers say it's because babies birthed in the fall months are much more likely to get common wintertime viral infections like respiratory syncytial virus (RSV), a major cause of respiratory illness in young kids.
At birth, infants have protection against certain diseases because antibodies have passed through the placenta from the mother to her unborn baby. After birth, breastfed infants get the continued benefits of additional antibodies in breast milk. But in both cases, all of that protection is temporary. So, as their immunities fade, babies become more susceptible to infections, especially in the winter months when all kinds of germs are swirling through the air.
So, what's that have to do with asthma? Well, children who've had RSV or bronchiolitis (which is usually caused by a viral infection, most commonly RSV) may be more likely to develop asthma later in life. But the jury's still out on whether these illnesses actually cause asthma or whether children who eventually develop asthma were simply more prone to developing those sicknesses as infants anyway. Research continues into the relationship between RSV, bronchiolitis, and the later development of asthma.
In the meantime, though, the researchers in this latest study say preventing infections with common winter viruses in babies could help prevent asthma, too.
What This Means to You
Asthma can be tough to diagnose in kids under the age of 5, especially in infants, because other conditions have similar symptoms.
Bronchiolitis, in particular, often mimics asthma in babies. The infection affects the tiny airways (called bronchioles), causing them to become narrowed, which makes breathing more difficult. Infants often are affected because their airways are so small that they become blocked more easily than those of older kids or adults. Symptoms of bronchiolitis include rapid breathing, a cough, wheezing, and fever
For kids with asthma, viral infections (like RSV, bronchiolitis, and the common cold or flu) can trigger asthma symptoms or make them worse. Kids may react to triggers (like viruses, animal dander, dust, mold, and pollen) over time, with gradual exposure, or suddenly and without warning. The result is usually an asthma flare-up (or attack) — when the lungs' already-inflamed airways become more swollen and clogged with sticky mucus, and the muscles around the airways tighten, leaving little room for air to flow through.
Whether your child has asthma or not, it's always wise to try to keep infectious bugs at bay. To keep them from invading your household:
- Especially during cold and flu season, try to steer clear of crowded places (like shopping malls) and anyone with a cough, cold, or the flu if you have an infant.
- Make sure everyone who comes in contact with your baby washes their hands well and often.
- Teach young kids how to wash their hands right every time (and make sure you do the same!):
- Use warm water and soap and lather up for about 10 to 15 seconds.
- Get in between the fingers and under the nails where uninvited germs like to hang out. And don't forget the wrists!
- Rinse, then dry well with a clean towel.
To minimize the germs passed around your family, make frequent hand washing a rule for everyone, especially:
- before eating and cooking
- before and after visiting or taking care of any sick friends or relatives
- after using the bathroom
- after cleaning around the house
- after touching animals, including family pets
- after nose-blowing, coughing, or sneezing
- after playing with other children or on playground equipment
- after being outside (playing, gardening, walking the dog, etc.)
The few seconds you all spend at the sink every day could save you some trips to the doctor's office!
Reviewed by: Steven Dowshen, MD
Date reviewed: December 2008
Source: "Evidence of a Causal Role of Winter Virus Infection during Infancy in Early Childhood Asthma," American Journal of Respiratory and Critical Care Medicine, Dec. 1, 2008.