acarid /ak″ərid/ , one of the many mites and ticks that are members of the order Acarina, which includes a great number of parasitic and free-living organisms. Adults have four pairs of legs and round bodies, living as ectoparasites. Most are yet not described, but several types are of medical interest because they infect humans. Those associated with disease act as intermediate hosts of pathogenic agents, directly cause skin or tissue damage, and cause loss of blood or tissue fluids. Important as vectors of scrub typhus and other rickettsial diseases are the six-legged larvae of mites from the family Trombiculidae, which are parasites of humans, many other mammals, and birds. See also chigger, scabies.
