An infection can happen when a foreign organism enters a person’s body and causes harm.
The organism uses that person’s body to sustain itself, reproduce and colonize. These infectious organisms are known as pathogens. Examples of pathogens include bacteria, viruses, fungi and prions. Pathogens can multiply and adapt quickly.
Some infections are mild and barely noticeable, but others are severe and life-threatening, and some are resistant to treatment. Infection can be transmitted in a wide array of ways.
These include skin contact, bodily fluids, contact with feces, airborne particles and touching an object than an infected person has also touched. How an infection spreads and its effect on the human body depend on the type of agent.
The immune system is an effective shield against infectious agents; however, colonies of pathogens may grow too large for the immune system to fight. At this stage, infections start to become harmful.
A lot of pathogens give off toxins that trigger negative responses from the body.