You freely admit to not knowing anything about monitors, you even admit to not knowing anything with zoonosis and lizards! Here I am saying north American parasites aren't developed to the point of being able to pose a problem to a monitor, I'd even be so inclined to say 99% of the probably couldn't take hold in a monitor even if given the chance- due to the acidity of a monitor's stomach.
The OP asked about parasites, yes wild bugs may have them, no they won't hurt your monitor, neither will trace amounts of insecticides. People with 0 monitor experience or husbandry experience with monitors should stay out of the monitor forum. It's not a snake, and is the opposite of a snake in so many ways it's not even funny.