Parasitology Glossary

The process by which parasites alter their surface proteins to evade the host immune response, enabling chronic infection.

The free-swimming larval stage of trematodes (flukes) that emerges from snail intermediate hosts and can penetrate human skin.

The dormant, environmentally resistant stage of a protozoan parasite that facilitates transmission between hosts.

The host organism in which the parasite reaches sexual maturity and reproduces sexually.

A parasite that lives on the external surface of the host, such as ticks, lice, fleas, and mites.

A parasite that lives within the body of its host, such as intestinal worms or blood-dwelling protozoa.

A parasitic worm; the three major groups are nematodes (roundworms), cestodes (tapeworms), and trematodes (flukes).

An organism that harbors a parasite and provides it with nourishment and a habitat for growth and reproduction.

The strategies employed by parasites to avoid recognition and destruction by the host immune system, including molecular mimicry, antigenic variation, and immunosuppression.

A host organism required for parasite development but in which the parasite does not reach sexual maturity.

The complete series of developmental stages a parasite undergoes from egg or infective form to mature adult, often involving multiple hosts.

The distribution of antiparasitic medication to entire at-risk populations to reduce disease burden, regardless of individual diagnosis.

A stage in the asexual reproduction of apicomplexan parasites that results from schizogony and invades host cells (e.g., red blood cells in malaria).

A tropical infectious disease that primarily affects impoverished populations and historically receives inadequate research funding and public health attention.

A thick-walled structure produced during the sexual phase of apicomplexan parasites (e.g., Toxoplasma, Cryptosporidium) that contains infectious sporozoites.

An organism that lives in or on another organism (host) and benefits at the host's expense.

A host in which a parasite survives without undergoing further development but which may serve to transfer the parasite to the definitive host.

The biological mechanism by which a parasite causes disease, including tissue invasion, nutrient depletion, toxin release, and immunopathology.

The proportion of a population found to have a parasitic infection at a specific point in time.

Single-celled eukaryotic organisms, including many parasitic species such as Plasmodium, Giardia, and Trypanosoma.

An animal host that maintains a parasite in nature and serves as a source of infection for other susceptible hosts, including humans.

A form of asexual reproduction in apicomplexan parasites involving multiple nuclear divisions followed by cytoplasmic division, producing many merozoites.

The active, motile, feeding stage of a protozoan parasite, as opposed to the dormant cyst stage.

An organism, typically an arthropod, that transmits a parasite or pathogen from one host to another.

An infectious disease that is naturally transmissible from animals to humans.