I just asked my 22 year old friend on what she thought a parasite was and, after thinking for a while, she said, “It’s a bug… a bitey bug”. While partially correct, there’s a lot more to a parasite than just biting you.
A parasite is basically an organism that participates in a relationship with another organism, where the parasite benefits while simultaneously hurting the other organism. There are two types of parasites: ectoparasites and endoparasites.
An ectoparasite is what my friend was referring to as a ‘bitey bug’, such as a mite or a tick. Ectoparasites are outside of the organism with whom it shares a relationship with (Ecto is Greek for ‘outside’).
Endoparasites, which is the type of parasite that was mentioned in the post about Gastroenteritis, can be viruses, bacteria, or protists. These parasites live inside of the organism it wants to be in a relationship with (Endo is Greek for ‘inner’ or ‘internal). So, while the host is providing these parasites with nutrients that hits the spot just right, the parasites may repay the host by releasing toxic wastes that hurt the host or by behaving like viruses and killing cells, though those are just a couple of the rude, ungrateful acts these parasites do.
The parasite is basically that person who goes into a hotel room, stays the night, trashes the place, and then leaves without paying; not really someone we want to be associated with.