Aids is one of the disease that damage little by little the immune system until the human body die.
Particles in solids move ever so slightly. They are not completely at rest, but since they are so packed together it’s difficult for them to move. That’s what makes a solid a solid. Particles in liquids slide and move past each other fairly quickly, and have space to move. Particles in gases are the most spread apart, and because of this, they move the quickest. Hope this helped.