Infection is not a thing of the mind, but a disease, which can be in any form such as bacteria or virus.
Infection can also mean an illness that is caused by bacteria or virus and that affects one part of the body and spread as time goes by untreated. Infection can be gotten through sex, through dirty untreated toilet and through blood contact.

Viral infection does not spend much before causing its expected harm such like HIV/AIDS, Ebola, H1N1, Mers and others.virus kills infected people very fast and easily, by shutting down the body defense system and inflicting its harm. Viral infection can easily be detected very physically at its secondary stage.

At this stage, people would start asking questions, whether the person is actually sick or not. It is visible between weeks or few years, in the case of bacterial infection, it stays and settles down in your body system, with no prior knowledge, that something strange is inside your body.
http://healthful.com.ng/dying-of-infection/

infection kills silently