In general, pathogens are organisms that cause diseases. There are naturally many microbes in human bodies. Nevertheless, they only trigger a health issue when they manage to penetrate a normally sterile area of the body or when the immune system becomes weak. Pathogens can vary and result in different conditions. All they need is a host to survive and thrive. Once they have set up in your body, they could use resources in the body to replicate and spread to other hosts. There are a few ways that pathogens can be transmitted, such as bodily fluids, skin contact, feces contact, or airborne particles.