The response to infection.

Covered pathogenic organisms and the stages of infection leading to disease, illustrating the tremendous variety of organisms and disease processes to which the body is exposed. Now we turn to the problem of how the body attempts to counter the threats posed by this enormous number of different infectious organisms.
The response to infection can be divided into five stages:
1. Awareness of infection. Obviously the body cannot begin to mount a defensive response against a pathogen until it is aware of the presence of the pathogen.
2. The immediate response to infection. This involves the activity of cells and other factors that are present at the time of infection but may require their recruitment to the site of infection and activation once there.
3. The delayed response to infection. If the immediate response to infection is not effective in eliminating the pathogen, the next stage is to generate new cells and factors to deal with the infection.
4. Destruction or elimination of the pathogen or neutralisation of the threat posed by pathogens. The optimal way of dealing with pathogens is to kill them or eliminate them from the body. However, in some cases where pathogens are producing a powerful toxin it may be more beneficial to neutralise the toxin first before attempting to destroy or eliminate the pathogen.
5. Provision of immunity so that you do not get ill if you are infected again with the same pathogen.