our body is having various methods to keep diseases at the very doorstep. When the pathogens enter our body, then our body starts reacting in the form of fever, sneezing , cough etc.. Through fever body is reducing the chance of pathogens spreading easily. Because in very high and cold temperatures pathogens will not exit.
When the germs get entered in to our body through injuries our body undergoes some process( I forgot it's name) and as result the injured part gets swelled and this will take more amount of blood to that area. Here ,at the same time the body wall gets widened and this enable wbc to reach near the germs and they destroy them.
Even after this the germs enter our body , our body produces certain substances to destroy them