My brother is 18 years old but don't mix his age with his knowledge of health, he leaves a lot of mess around our house but claims that it is fine or my mother and I are just overreacting, but frankly I am getting sick of his mess (also my mother as well but not as much as me).
My brother sticks gum to surfaces, once sticking gum next to my laptop, he leaves gum wrappings all over the house. My brother enjoys eating almonds but ends up leaving around 5-7 almonds on the floor and claims he "forgot" he dropped them. He leaves bones and plastic in the sink, he leaves bowls with food left in them around the house for days, once even leaving a tea-bag in a cup for so long, mold started to grow. He leaves breadcrumbs all over his table and his bed is absolutely disgusting; with his hair and stains all over it. A lot of times when my friends come over, they mention to me later how filthy my brother's table is. The worst out of all of this is that he expects my mother and I to clean it.
Here is even a link to an image of my brother's keyboard, which he claims is clean. https://imgur.com/a/Nk9eI
If you were to take out the keys on the keyboard (Which I have done before), you will find a mother load of food smudge into the keyboard.
I have been getting so fed up with this mess and I have been trying to tell him to stop but he thinks that I am just overreacting, my brother denies that he is unhealthy. Is there anything I could do to stop him from making this mess in the first place? Because it is getting out of hand and my mother and I don't have time to continue to clean up after him.