(sleeping sickness), ''Acanthamoeba'' keratitis, and primary amoebic meningoencephalitis (naegleriasis).

Parasitic worms (helminths) are macroparasites that can be seen by the naked eye. Worms live and feed in their living host, acquiring nutrients and shelter in the digestive tract or bloodstream of their host. They also manipulate the host's immune system by secreting immunomodulatory products