Medical Parasitology – Lecture 1 Vocabulary

A comprehensive set of vocabulary flashcards covering key terms and concepts introduced in Lecture 1 on Medical Parasitology.

Parasitology

Branch of biology that studies the dependency of parasites on their hosts and the interactions between host populations and the parasites that infect them.

Parasitism

Two-species association in which the parasite lives on or in the host for a significant period and obtains nourishment from it.

Epidemiology

Study of diseases in human populations, focusing on transmission, distribution, prevalence and incidence rather than individual cases.

Taxonomy

Science concerned with the principles of classifying organisms.

Commensalism

Relationship in which one organism benefits and the other is neither helped nor harmed.

Mutualism

Association between two organisms in which both species derive benefit.

Symbiosis

Intimate or close association between two dissimilar organisms; may include parasitism, commensalism or mutualism.

Vector

Insect or animal that transmits a disease agent to another animal or to humans; essentially a carrier.

Biological vector

Living carrier in which the pathogen develops or multiplies before transmission to the next host.

Mechanical vector

Carrier that transports pathogens on or in its body without pathogen development or replication.

Accidental host

Organism that is not the usual host for a parasite but becomes infected by chance.

Definitive host

Host in which a parasite reaches adult stage and reproduces sexually; the final host.

Intermediate host

Host that harbors immature or asexually reproducing stages of a parasite; parasite does not reach sexual maturity here.

Reservoir host

Host that harbors an infectious agent and can serve as a source of infection for humans.

Paratenic host

Transport host in which no parasite development occurs but which bridges an ecological or trophic gap in the life cycle.

Endoparasite

Parasite that lives inside the tissues or organs of its definitive host.

Ectoparasite

Parasite that lives on the skin or external surfaces of its definitive host.

Obligate parasite

Organism that cannot survive or complete its life cycle without a host.

Facultative (opportunistic) parasite

Organism capable of both free-living and parasitic existence, e.g., Naegleria, Acanthamoeba.

Infection

Relationship between an endoparasite and its host.

Infestation

Relationship between an ectoparasite and its host.

Zoonosis

Animal disease that is transmissible to humans.

Parasitosis

State of infection or infestation with an animal parasite.

Pathogen

Parasite capable of causing local or systemic damage to its host.

Super-infection

Re-infection of a host already harboring the same species of parasite.

Autoinfection

Super-infection in which the infected person is the direct source of his or her own re-exposure.

Host specificity

Degree to which a parasite is restricted to particular host species.

Anthropophilic

Having a preference for feeding on human blood, as with certain anopheline mosquitoes.

Microparasite

Unicellular or acellular agent (e.g., protozoa, bacteria, viruses, fungi) that multiplies within the host, has short generation time and often causes acute disease.

Macroparasite

Multicellular parasite (e.g., helminths, arthropods) that rarely multiplies in the host, has long generation time and commonly causes chronic infections.

Trophozoite

Active, feeding and reproducing stage of a protozoan parasite.

Cyst

Dormant, resistant stage of many protozoa; commonly the infective stage for new hosts.

Encystation

Process by which a protozoan forms a cyst when environmental conditions become unfavorable.

Predilection site

Preferred location in the definitive host where adult parasites reside and reproduce.

Diagnostic stage

Stage of a parasite that leaves the definitive host and can be detected for diagnosis.

Biological incubation period

Time between infection and the point when parasite or its products can first be demonstrated in the host.

Pre-patent period

End of the biological incubation period; interval before infection becomes patent (detectable).

Clinical incubation period

Interval between exposure and the earliest symptoms due to infection or infestation.

Person-to-person transfer

Direct transmission of parasites that have only trophozoite stages, e.g., Trichomonas vaginalis.

Infective stage

Specific developmental form of a parasite capable of initiating infection in a new host.