parasitology

Abundance

number of parasites in one specific host individual.

Accidental host

a host a parasite mistakenly infects but can't thrive in; usually a dead end.

Amastigote

rounded, non-flagellated kinetoplastid life stage (intracellular, proliferative).

Apical complex

specialized invasion structure at one end of an apicomplexan cell (polar ring, conoid, micronemes, rhoptries).

Apicoplast

vestigial, non-photosynthetic plastid retained by most Apicomplexa; a drug target.

Apomorphy

a derived character state.

Autapomorphy

a derived trait unique to one lineage.

Definitive host

host where the parasite reaches sexual maturity.

Density

average parasites per host across a whole sampled population (infected + uninfected).

Ectoparasite

lives on the outside of the host.

Endoparasite

lives inside the host.

Endosymbiosis

origin of mitochondria/chloroplasts via one cell engulfing and retaining another as a permanent symbiont.

Epimastigote

flagellated kinetoplastid stage found reproducing in the insect vector.

Epizootic disease

outbreak disease in animals with potential to spread to humans.

Facultative parasite

can live free or parasitically.

Gamogony

sexual reproductive phase of the apicomplexan life cycle.

Hyperparasite

a parasite of a parasite.

Incidence

number of newly infected hosts over a specified period.

Intensity

average parasites per infected host only.

Intermediate host

host required for an obligate developmental step.

Kleptoparasite

steals food/resources from another organism without feeding on its tissue.

Long branch attraction (LBA)

phylogenetic artifact grouping unrelated fast-evolving lineages together.

Merogony (schizogony)

asexual reproductive phase producing merozoites.

Micropredator

attacks many hosts repeatedly without killing them (e.g., mosquito).

Monophyletic

common ancestor + all its descendants (a true clade)

Obligate parasite

must have a host to complete its life cycle.

Oocyst

tough, resistant, infective stage of Apicomplexa (and some other protists) containing sporozoites.

Paraphyletic

common ancestor + some but not all descendants.

Parasitic castrator

sterilizes the host and redirects its reproductive energy to itself.

Parasitoid

develops inside one host and (almost) always kills it.

Paratenic/transport host

used only for dispersal; no development occurs there.

Phoresis

hitchhiking symbiosis with no feeding interaction.

Plesiomorphy

an ancestral character state.

Polyphyletic

doesn't include the common ancestor; based on convergently evolved traits.

Polytomy

a tree node with 3+ unresolved branches.

Prevalence

fraction of a population infected at a given time.

Sporogony

meiotic/asexual phase producing sporozoites within an oocyst.

Synapomorphy

a shared derived character state, useful for identifying real clades.

Systematics

classification reflecting evolutionary relationships.

Taxonomy

naming and classifying organisms.

Trophically transmitted parasite

requires a host to be eaten by a predator to complete its cycle.

Trophozoite

the active, feeding, motile stage of many protist parasites.

Trypomastigote

flagellated, elongated kinetoplastid stage found in the mammalian bloodstream.

Vector

organism (often an arthropod) that transmits a parasite between hosts.

VSG (Variable Surface Glycoprotein

Trypanosoma brucei's antigen-switching surface coat protein.