INSTRUCTIONAL TEXT COMPREHENSIVE
STUDY GUIDE 2026 PARASITES AND
INFECTIOUS DISEASE PRINCIPLES
◉ Protozoology.
Answer: The study of protozoan parasites.
◉ Helminthology.
Answer: The study of helminth (worm) parasites.
◉ Symbiosis.
Answer: Living together of UNLIKE organisms, which may involve
protection or other advantages to one or both organisms.
◉ Commensalism.
Answer: A symbiotic relationship in which two species live together
and one species benefits from the relationship.
◉ Mutualism.
Answer: A symbiotic relationship in which two organisms mutually
benefit from each other.
, ◉ Parasitism.
Answer: A symbiotic relationship where one organism, the parasite,
lives in or on another, depending on the latter for its survival and
usually at the expense of the host.
◉ Obligatory parasite.
Answer: Parasite that cannot survive outside the host.
◉ Facultative parasite.
Answer: Parasite that is capable of existing independently of a host.
◉ Endoparasite.
Answer: Parasite that is established inside of a host.
◉ Ectoparasite.
Answer: Parasite that is established in or on the exterior surface of a
host.
◉ Definitive Host.
Answer: Aka Final Host; adult sexual phase of parasite development
occurs.