The vast majority of medically important pathogens infect their host across a body surface such as the skin, or across a mucosal tissue such as the respiratory tract or intestines, as these sites are the ones exposed to the external environment.

AJ is an 8-year-old techie who drives monster-truck Blaze, the top racer in Axle City. The two go on adventures that have them taking on problems involving science and math. Many predicaments they face are caused by Blaze's rival, Crusher, a tractor-trailer that will do anything to beat other vehicles to the finish line. The animated series is billed as the first TV show for preschoolers to comprehensively cover areas of science, technology, engineering and math. Each episode introduces different STEM concepts, including buoyancy and trajectory.