Parasitology Exam 1 Terms

Phoresis

Involves two organisms traveling together without any biological or physiological interdependence

Mutualism

Both organisms benefit, often with a necessary physiological reliance; typically obligatory

Commensalism

One organism benefits while the other is unaffected, such as Entamoeba gingivalis in the human oral cavity

Parasitism

One organism either harms or lives at the expense of its host

Definitive Host

The host where the parasite achieves sexual maturity

Intermediate Host

Necessary for the parasite’s developmental stages but without sexual maturation

Paratenic (Transport) Host

Doesn’t support parasite development but can help bridge ecological gaps between hosts

Reservoir (Amplifying) Host

Can carry a pathogen indefinitely without harm

Dead-end/Incidental Hosts

Doesn’t develop high parasite levels; unable to transmit the pathogen further

Hyperparasitism

Parasite hosting another parasite

Vector

Organism, often an arthropod, transmitting a pathogen from reservoir to host

Aberrant Host

Atypical host for the parasite it carries

Host Specificity

Some parasites are specific to one host, while others can develop in multiple hosts

Ectoparasite

Lives on host’s surface (Tick-Ixodes scapularis)

Endoparasite

Lives in host (Trypanosoma brucei/Plasmodium falciparum)

Facultative Parasite

Doesn’t rely on the host for survival; incidental

Obligate Parasite

Needs a host for survival and life cycle completion

Mechanical Damage

Causes physical harm or obstruction in tissues

Physiologic Damage

Affects metabolism;comsumes host’s nutrients

Direct Life Cycles

Parasite completes its life cycle within a single host species

Indirect Life Cycles

Requires multiple host species for completion, typically involving 2-3 hosts: definitive, intermediate, and paratenic

Prevalence

proportion of a populations infected at a specific time

Incidence

Rate of new infections in a population

Morbidity

Refers to illness or disease state

Co-morbidities

Presence of simultaneous illnesses

Mortality

Incidence of death due to a disease

Polyembryo

Development of many offspring from a single zygote, occurs in larval stages

Internal Budding

New individual grows from somatic tissue of parent

Schizogony (multiple fission, merogony)

Produces many daughter cells, nucleus divides many times before cytokinesis occurs

Binary Fission

Mitotic division of 1 cell into 2

Monoecious (Hermaphroditism)

A single individual possesses gonads of both genders, self-fertilization, can however, mate with others

Dioecious

Each individual is a separate gender, sexual dimorphism

Oocyst

thick-walled, resistant spore to form that contains zygote and is produced after sexual reproduction

Schizogony/Merogony

production of merozoites

Merozoite

nonmotile, egg-shaped/ spherical cells specialized for entering red blood cells

Gametogony

Production of zygotes

Zygote

diploid cell formed when two haploid gametes fuse during sexual reproduction in protozoans

Sporogony

production of sporozoites

Sporozoite

infect, motile stage of certain parasitic parazoa

Schuffner’s Dots (granule)

any of the fine, round, uniformly red or red-yellow staining dots occurring in red blood cells infected with Plasmodium vivax or P. ovule

Hemozoin

a disposal product formed from the digestion of blood by some blood-feeding parasites

Hypnozoites

exoerythrocytic schizozoite of P. vivax or P. ovale in the human liver, characterized by delayed primary development (thought to be responsible for malarial relapse)