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50 TERMS PART2
PARASITOLOGY PART2
Term | Definition |
---|---|
Stoll’s method (methods) | A technique for counting nematode and trematode eggs in a faecal sample diluted in a 0.1 M caustic soda solution. |
Willis technique (parasitology methods) | A flotation method, utilizing saturated common salt solution to float helminth eggs, and hence separate eggs from faecal (USA: fecal) debris. The eggs can then be counted in a faecal sample. Suitable for most nematodes but not for cestodes or trematodes. |
Myiasis | Invasion of the body by the larvae of flies, characterized ascutaneous (subdermal tissue), gastrointestinal,nasopharyngeal, ocular or urinary, depending on the region invaded. |
Nits | NitsThe egg containers of lice. |
Metamorphosis | Change of structure or shape, particularly, transition from one developmental stage to another, as from larva to adult form. |
Complete metamorphosis | A term used in relation to arthropods. Holometabolous. The cycle of development involves egg, larva, pupa and adult. Each stage is morphologically distinct from the other. |
Scutum | A protective covering or shield, e.g. a chitin plate in the exoskeleton of hard-bodied ticks. |
Proboscis | Tube-like organ of varying form and functions. In insects, a proboscis is a filamentous structure that projects outwards from the mouthparts, functioning as a piercing and sucking device for obtaining liquid food. |
\Insect vector | Insects may carry infection mechanically on feet or mouthparts, by passage through the digestive tract but without the insect being infected, or by becoming an intermediate host with some part of the parasite’s life cycle taking place in insect tissues. |
Intermediate host | Required host in the life cycle in which essential larval development must occur before a parasite is infective to its definitive host or to additional intermediate hosts. |
Parasite | Plant or animal that lives upon or within another living organism at whose expense it obtains some advantage. Among the many parasites in nature, some feed upon animal hosts, causing diseases ranging from the mildly annoying to the severe and often fatal. |
Parasitism | Intimate relationship between two organisms in which one (the parasite) derives benefit from the other (the host), usually to obtain food or physical support. Parasitism can have minor or major effects on the survival of the host. |
Slime balls | Form in which the cercariae of Dicrocoelium dendriticum are discharged from the intermediate host snail’s lung. The cercariae become infective only if the next intermediate stage, the ant, ingests the slime ball. |
Temporary parasite | A parasite that lives free of its host during part of its life cycle (e.g. bed bug, mosquito). |
Accidental host | An animal host to a parasite which is not the usual host species for that parasite. |
Autoinfection | In parasitology used to describe a host which is both intermediate and definitive host without parasite transmission from other animals, which may be particularly damaging due to the large number of offspring many parasites produce. |
Definitive host (primary host, final host) | The host in which the sexual reproduction of a parasite takes place. |
Infection | Invasion by and multiplication of micro-organisms in body tissue which may or may not result in overt disease. The organisms concerned are called pathogens, and include protozoa, and worms. |
Infestation | The presence on or in the body of parasites mites and fleas, or other multicellular organisms, such as ticks; sometimes used to denote parasitic invasion of the organs and tissues, as by helminths. |
Insect larva | The second stage in the standard insect life cycle, the maggot or caterpillar. |
Insect pupa | The third stage in the insect life cycle. An inert, dormant stage from which the adult emerges. |
Imago | The adult or definitive form of an insect. |
Fecal-oral (mode of transmission) | Through non-observance of personal hygiene rules (dirty hands and domestic articles, unwashed vegetables and fruits, unfiltered water); e.g. Amebiasis, Lambliasis, Ascaridiasis, Echinoccosis. |
Alimentary (mode of transmission) | Parasite is present in tissues of the animals used in food; e.g. Toxoplasmosis, Opisthorchosis, Taeniasis, Trichinosis. |
Peroral way of transmission | Through the mouth. |
Percutaneous way of infection | Through skin and mucous membrane. |
Direct penetration (mode of infection) | e.g. cercaria of Schistosoma, larvae of Ancylostoma |
Contact-household (mode of infection) | Through using common towels, sponges, linens or through handshakes; e.g. urogenital trichomoniasis, itch. |
Transmissible (mode of infection) | Through a specific carrier, e.g. leishmaniasis, trypanosomiasis, malaria. |
Intranasal way of infection | Through the nose. |
Air-drop (mode of infection) | e.g. naegleriasis, acanthamoebiasis. |
Air-dust (mode of infection) | e.g. toxoplasmosis, acanthamoebiasis. |
Haemotogenous way of infection | Through blood |
Transplacental (mode of infection) | Transmission occirs congenitally via placenta to newborns from sick pregnant women; e.g. toxoplasmosis, Chagas` disease. |
Haemotransfusion (mode of infection) | Through blood donor; e.g. Chagas` disease. |
Transsexual way of infection | From sexual parthner through matter discharged in which the parasiteis present; e.g. urogenital trichomoniasis. |
Mechanical vector | This is a vector which assist in the transfer of parasitic forms between hosts but is not essential in the life cycle of the parasite, e.g. housefly, cockroach. |
Specific vector | This is an arthropod in the organism of which the agent of disease has certain stages of development or reproduction, e.g. sandfly, kissing bug, tsetse fly. |
Inoculation | This is introduction of infecting agent in wound by the bite of an infected vector. |
Contamination | This is introduction by faecal matter of the vector being rubbed into the wound caused by a bite or by a possible contamination of the conjunctivae and other exposed mucous membranes with fingers. |
Anthroponosis | A parasitic disease, the agents of which are transmitted by vectors exclusively from human to human, e.g. malaria, louse-borne spotted fever. |
Zoonosis | A parasitic disease in which only an animal is the host. |
Anthropozoonosis | A parasitic disease in which an animal is normally the host but which can also infect humans. |
Feral nidal diseases | Areal of distribution of a certain illness takes place among wild anmals, e.g. leishmaniasis, tick-born encephalitis, trypanosomiasis. |
Synanthropic desease | Territory of distribution of a certain illness occurs among domestic animals and humans, e.g. malaria, schistosomiasis, dracontiasis. |
Transmissible infection | An infection capable of being transmitted from one animal to another. Also termed contagious. |
Pathogenic stage | This is form of the parasite in its life cycle causing the development of disease in an organism of the host. |
Heteroxenous life cycle | Requiring more than one host to complete the life cycle. |
Obligate parasite (or holoparasite) | This is a parasitic organism that cannot complete its life-cycle without exploiting a suitable host. |
Shedding | Excretion of an infectious agent from the body of an infected host. |