Upper respiratory infections are the most common causes of illness in childhood. Bronchitis is an inflammation of the main air passages to the lungs, the bronchi. Bronchitis may be acute (short lived) or chronic, meaning that it lasts a long time and recurs often. Acute bronchitis usually is caused by viral or bacterial infections. Chronic bronchitis generally is due to long-term exposure to irritants like cigarette smoke.

When it is severe enough to require hospitalization, respiratory illness greatly increases the risk of childhood asthma.

Fortunately, at 9 months your baby's immune system has developed and is better able to fight infection than during the first months of his life. Lymph nodes and vessels are major components of his immune system. Lymph nodes are bundles of lymph tissue found throughout the body that collect and break down toxins and other waste products. Lymph vessels transport lymph, a clear fluid that comes from the spaces between cells throughout the body. Other important components of your babyâ's immune system include macrophages, white blood cells that surround and digest pathogens such as bacteria and fungi.

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Related Health Centers:

Infant Nutrition Health Center, Mother-Baby Bond Health Center, Mother’s Milk Health Center, Monthly Infant Development Calendar Health Center,Weekly Pregnancy Calendar Health Center