How do germs get inside the body?

Germs enter the body through openings and breaks: the nose, mouth, eyes, and cuts in skin. They can travel in breath droplets, ride on hands to the face, or get into a scrape. Once inside, they try to attach to cells and multiply before the immune system stops them.

Most of the time, the body handles tiny intrusions quietly. White blood cells patrol, mucus traps particles, and skin blocks nearly everything. You usually feel ill only when germs grow fast enough, or make irritating chemicals, that your body has to fight harder.