Parasitology and Immunology Lecture Notes

Flashcards covering the fundamentals of parasitology, organismal interactions, host-parasite coevolution, classification, and basic immunology based on lecture material.

Parasitology

The study of the most common mode of life on earth; centered on animal parasites of humans, domestic animals, and wildlife.

Parasite

An organism that lives in or on another organism (host) and either harms the host or lives at the expense of the host.

Symbiosis

Interaction among organisms in which one organism lives with, in, or on the body of another ($(+) (+)$).

Neutralism

A lack of benefit or detriment experienced by either member of the pair of interacting organisms; the fitness of one species has absolutely no effect on the other ($(0) (0)$).

Competition

An interaction where there is an overlap in ecological niches such that both populations depend on the same food source, shelter, or resources and negatively affect each other ($(-) (-)$).

Phoresis

A form of symbiosis where the symbiont (phoront) is mechanically carried about by its host with no physiological dependence ($"to carry"$).

Protocooperation

A mutually beneficial symbiosis between organisms in which the interaction is not physiologically necessary to the survival of either ($(+) (+)$).

Mutualism

A type of symbiosis in which both host and symbiont benefit from the association and there is usually a physiological dependence ($(+) (+)$).

Commensalism

A kind of symbiosis in which the symbiont (commensal) benefits, and the host is neither harmed nor helped ($(+) (0)$).

Amensalism

An asymmetrical interaction in which one organism causes a negative effect on another without being positively or negatively affected in return ($(-) (0)$).

Predation

An animal interaction in which a predator kills its prey outright and does not subsist on the prey while it is alive ($(-) (+)$).

Macroparasites

Large parasites that do not multiply in the host of interest, have stable populations, and cause endemic diseases (e.g., helminthes).

Microparasites

Small parasites that multiply within the host of interest, induce lasting immunity, and cause epidemic diseases (e.g., fungi, protists, bacteria, and virus).

Endemic

A term describing a disease or condition that is found "in or within people" from a particular area.

Epidemic

A term describing the spreading of disease "above or on people."

Obligate parasites

Parasites that cannot complete their life cycle without spending at least part of the time in a parasitic relationship.

Facultative parasites

Organisms that are not normally parasitic but can become so when accidentally eaten or entering a wound or orifice (e.g., $Naegleria fowleri$).

Accidental (incidental) parasite

A parasite found in a host other than its normal host.

Permanent parasite

A parasite that lives its entire adult life within or on a host (e.g., $Trichinella spiralis$).

Temporary (intermittent) parasite

Also known as micropredators; organisms that contact their host only to feed and then leave (e.g., mosquitoes, bed bugs, fleas).

Parasitoid

An organism that is a typical parasite early in its development but finally kills its host during or at the completion of its development.

Hyperparasitism

A condition in which an organism is a parasite of another parasite (e.g., $Plasmodium spp.$ in $Anopheles$ mosquitoes).

Colozoic

A parasite living in the lumen of a hollow organ, such as the intestine.

Histozoic

A parasite living within the tissues of a host, such as the liver.

Vector

Any agent, such as water, wind, or an insect host, that transmits a disease organism.

Definitive host

The host in which a parasite achieves sexual maturity.

Intermediate host

A host in which a parasite develops to some extent but not to sexual maturity.

Paratenic (transport) host

A host in which a parasite survives without undergoing further development.

Reservoir host

A host that serves as a means of sustaining a parasite when it is not infecting humans, typically another suitable definitive host.

Urban (domestic) cycle

A parasite cycle that is normal to the human environment and involves domesticated animals.

Sylvatic cycle

A parasite cycle existing normally in the wild involving wildlife.

Preadaptation

The possession of a trait that coincidently predisposes an organism for survival in an environment different from its evolutionary history.

Adaptation

An evolutionary process, anatomical structure, physiological process, or behavioral trait that promotes the likelihood of survival and reproduction in a particular habitat.

Red Queen Hypothesis

Proposed by Leigh Van Valen ($1973$); the metaphor that species must "run" (evolve) just to stay in the same place (extant) to avoid extinction.

Binomial nomenclature

A system created by Carolus Linnaeus ($1707-1778$) where a species is given a compound name consisting of a genus and a species epithet.

Taxonomy

The study of scientific classification, including the ordering and naming of organisms.

Systematics

The study of classification and biological diversity within an evolutionary context to understand the origin of diversity.

Phylogenetic systematics (cladistics)

A methodology pioneered by Willi Hennig ($1913-1976$) to infer a species' evolutionary history based on shared derived character states.

Clade

A group of organisms that includes an ancestor and all descendants of that ancestor.

Synapomorphies

Shared derived characters that set a taxon apart from related taxa and their most recent common ancestor; these are considered informative characters.

Monophyletic

A group of taxa that includes a hypothetical ancestral taxon and all its descendants.

Paraphyletic

A group of taxa that includes a hypothetical ancestor but does not include all of the ancestor's descendants.

Polyphyletic

A group of taxa that do not share a most recent common ancestor and are defined by convergent traits (homoplasies).

Innate immunity

A broad, non-specific mechanism of defense that does not depend on prior exposure to the invader; the first and second lines of defense.

Adaptive (acquired) immunity

A specific mechanism of defense for particular nonself material that requires time for development and occurs more quickly on secondary response.

Lysozyme

An enzyme found in sweat, saliva, and tears that digests bacterial cell walls.

Macrophages

Active phagocytic cells that mature from monocytes, perform intracellular killing, and serve as antigen-presenting cells (APCs).

Neutrophils

The most abundant circulating leukocytes (50-70 \text{%}) and the first cells to arrive at the site of tissue damage or infection.

Eosinophils

Leukocytes (2-5 \text{%} of blood) important in eliminating parasites; high counts are associated with parasitic infection and allergic diseases.

Basophils

The least numerous circulating cells (0.5 \text{%}) that release mediators like histamine to promote inflammation; not important as phagocytes.

Natural Killer (NK) Cells

Innate immune cells that induce apoptosis in infected cells (cancer and viral) by releasing perforins and granzymes.

Mast Cells

Cells primarily located under mucosal surfaces that release histamine to promote inflammation and are triggered during allergic responses.

Delayed type hypersensitivity (DTH)

Cell-mediated immunity where a period of $24$ hours or more elapses between antigen introduction and the response (e.g., tuberculin skin test).

Anaphylaxis

A systemic immediate hypersensitivity involving a widespread rapid inflammatory response that can be fatal if the epiglottis swells to block the trachea.

Fibrosis

An abnormal and continuous wound repair process that fails to terminate, resulting in elevated levels of collagen and scarring.

Granulomas

Nodules of inflammatory tissue that may accumulate around persistent antigens.

Abscess

Localized necrotic debris that forms pus, causing an increase in hydrostatic pressure.

Ulcers

An area of inflammation that opens out to a skin or mucous surface.