A big focus of parenting is on keeping kids healthy. This is, of course, complicated by the fact the children’s immune systems are still developing. Children often encounter various infections ‘for the first time’- which means they have little pre-existing immunity and are prone to getting ill from these infections. In subsequent exposures to similar bugs, an immune memory will have been built up and the illness will tend to be less severe.
So what is this thing called the immune system?
The immune system is a maze of cells, tissues and organs that work together to:
– protect us from invading pathogens
– protect us from allergies (over-reacting to “benign” external allergens)
– protect us from auto-immunity (attacking our own cells)
– resist repeated infections
Parts of the immune system are innate (we are born with it) and parts are acquired (built up over time, usually after initial exposure or vaccination, to resist infections when they strike again). In addition, physical barriers such as an intact skin, stomach acidity, cilia (tiny little hair-like structures) beating in our noses and chests to clear infections, and even substances in our tears and saliva all help to clear offending bugs and pathogens.
How is a baby’s immune system established?
Our very initial immune system as a baby is derived from our bone marrow as well as antibodies transferred across the placenta. This is supported by further antibodies and anti-infective substances being transferred via the breastmilk.
The antibodies that come via the placenta “run out” around 6 months after birth- then suddenly the little immune system has a big job to do on its own!
This helps to explain why babies often have a relatively “healthy” period in the first 6 months- then between 6 and 18 months infections come in thick and fast!