Can chiggers spread throughout the body?

Not normally : (but maybe? Chigger bites often have a small red in the center of a welt ; occur in areas where skin is tender like the crotch, armpits, belt line, backs of knees, ankles. They are extremely itchy.

Define spread ?: Chiggers are insects that invade the superficial layers of your skin, often along belt lines where clothing or bindings are tight.They never enter the blood and generally do not go further than it takes for them to find a spot to burrow into your skin.