General Introduction to Medical Parasitology

Vocabulary-style flashcards defining core concepts, host types, parasite classifications, and pathogenic mechanisms in medical parasitology based on the lecture notes.

Medical parasitology

The branch of science that deals with the parasites which cause human infections and the diseases they produce.

Parasite

A living organism which receives nourishment and shelter from another organism where it lives.

Host

An organism which harbours the parasite.

Symbiosis

An association in which both organisms are so dependent upon each other that one cannot live without the help of the other.

Commensalism

An association in which the parasite only is deriving benefit without causing injury to its host.

Parasitism

An association in which the parasite derives benefit and the host gets nothing in return but always suffers some injury, however slight.

Ectoparasite (Ectozoa)

A parasite that lives outside on the body of the host, such as lice, ticks, or mites.

Endoparasite (Endozoa)

A parasite that lives inside the body of the host, occurring in blood, tissues, or body cavities; examples include protozoans and helminths.

Temporary parasite

A parasite that visits its host for only a short period.

Permanent parasite

A parasite that leads a parasitic life throughout the whole period of its life.

Facultative parasite

An organism that lives a parasitic life when the opportunity arises; e.g., Acanthamoeba and Naegleria.

Obligatory parasite

A parasite that cannot exist without a parasitic life; e.g., Plasmodium.

Occasional or accidental parasite

A parasite that attacks an unusual host; e.g., Echinococcus granulosus.

Wandering or aberrant parasite

A parasite that happens to reach a place where it cannot live; e.g., Toxocara canis.

Definitive Host

The host which either harbours the adult stage of the parasite or where the parasite utilizes the sexual method of reproduction; e.g., the mosquito in malaria.

Intermediate Host

The host in which the larval stage of the parasite lives or where asexual multiplication takes place; e.g., man in malaria.

Paratenic Host

A carrier or transport host where the parasite remains viable without further development.

Reservoir Host

A host that harbours the parasite and acts as an important source of infection to other susceptible hosts; e.g., a dog for hydatid disease.

Accidental Host

A host in which the parasite is not usually found; e.g., man is an accidental host for cystic Echinococcosis.

Incidental Host

A host that, though infected, is not necessary for the survival or development of the parasite; e.g., Trichinella spiralis.

Dead end host

A host in which the parasite cannot be transmitted further; e.g., in cases of trichinosis and hydatidosis.

Zoonosis

Diseases and infections which are naturally transmitted between vertebrate animals and man; a term introduced by Rudolf Virchow in 1880.

Direct life cycle

A life cycle in which only one host is required for the parasite to complete its development.

Indirect life cycle

A life cycle in which two or more hosts of different species are required for completion.

Lytic necrosis

Pathogenic damage produced by enzymes from parasites, such as Entamoeba histolytica lysing intestinal cells to produce ulcers.

Permunition

Concomitant immunity in which there is relative resistance to re-infection while the host still carries the infective organism.

Tolerance

A type of immune response where the infection continues without producing ill effects on the host.

Auto-infection

An infection where the source is the individual themselves; e.g., Enterobius.

Iatrogenic transmission

Transmission of a parasite through medical procedures; e.g., Malaria or Toxoplasmosis.