01. Intro to Parasitology Flashcards
What kind of parasite is Ascaris lumbricoides?
Roundworm/nematode
What kind of parasite is Trichuris trichiura? what is its common name?
Human whipworm - nematode
What kind of parasite is Clonorchis sinensis? What organ does it infect?
Liver fluke
What is the parasite responsible for Chagas’ disease?
Trypanosoma cruzi
What parasite causes leishmaniasis?
Leishmania
What parasite causes african sleeping sickness?
Trypanosoma brucei
What are common parasites in North America?
Pinworms Giardia Dog roundworm (dog heartworm) Toxoplasma (cat feces) Ticks (lyme disease)
Are bacteria or viruses parasites?
No, only eukaryotic organisms can be classified as parasites
What are the requirements to be a parasite?
May be an animal or a plant (eukaryotic)
Not bacterial or viral
Can be unicellular (malaria/toxo) or multicellular (worm/insect)
Can live in or on a host
Definition of parasite?
eukaryotic organism that acquires some of its basic nutritional requirements through its intimate contact with another living organism.
What are unicellular parasites called?
Protozoa
What are multicellular parasites called?
Metazoa
Define ectoparasite
lives on the external surface of another living organism
ex: head louse, tick, flea
Define endoparasite
lives within an organism
can be metazoan (Hookworm, tapeworm, roundworm, pinworm) or protozoan (Leishmania, Plasmodium, Trypanosoma, Giardia)
Define hemiparasite
Parasitic plant that derives some or all of its sustenance from another plant (ex: mistletoe)
Define definitive host
when the parasite reached sexual maturity in that host (ex: mosquito for malaria, cat for toxo)
Define intermediate host
parasite always asexual in this host; where the parasite completes a part of its life cycle and undergoes morphological changes and physiological changes (ex: human for malaria, mice for toxo)
Define reservoir host
alternate host from which the parasite can be transmitted to human or domestic animals. The parasite can still go through its life cycle - important source of infection in epidemiology (ex: rat for toxo)
Define accidental host
host that accidentally harbours an organism that is not usually parasitic in this host and cannot be transmitted. it is a dead end for the oarasite and can damage the host (ex: human and pork tapeworm Taenia solium, causes cysticercosis (in brain and eye)
Define vector
plays an active roll in Tmission of parasite, can be definitive or intermediate. transports the parasite from an infected to a non-infected host (ex: female Anopheles mosquito that Tmits malaria
Parasitism (process)
1) encounter: parasite meets the host
2) entry (may not be the location where damage occurs)
3) spread (this is at proper location, the parasite will propagate here)
4) multiplication
5) Damage: by parasite and or host response
6) outcome: parasite or host wins or coexist
what are the main modes of transmission?
- skin, respiratory, gastrointestinal, urogenital
- vector borne, blood transfusion, or organ transplant
what is external transmission? is there growth of the pathogen during this step?
- the passive carriage of the pathogen on the body or vector
- no
what is internal transmission?
- when the pathogen is carried within the vector
what are the two types of internal transmission?
- harbourage transmission: pathogen does not undergo changes within the vector (mechanical vector)
- biological transmission: pathogen undergoes changes within the vector (biological vector)
define infectivity
ability of the organism to establish a discrete, focal point of infection
define invasiveness
ability of organism to spread to adjacent or other tissues
penetration of host’s mucous membranes can be ______ or ______
- active
- passive
give examples of passive penetration
- skin lesions
- insect bites
- wounds
once below the mucous membrane, what does a parasite require for spread to deeper tissues?
- production of specific products and/or enzymes that promote spreading
- circulatory system gives the parasite full access to the body
define symbiosis
two species of organisms that lived together, with no implication regarding the length or outcome of the association
what are the 4 types of symbiosis?
- phoresis
- commensalism
- mutualism
- parasitism
which symbioses are considered “loose” associations?
phoresis and commensalism
which symbiosis are considered “intimate” associations?
mutualism and parasitism
define phoresis
- to carry
- an association in which one species provides shelter, support, or transport for another organism of a different species
define commensalism
- “at the same table together”
- one member of the association benefits (one way benefit) while the other is not affected. no harm is exerted in either direction
define mutualism
- reciprocal
- highly inter-dependent association, to the extent that the both species benefit from the association in terms of their growth and survival
- two way benefit, no harm
define parasitism
- intimate relationship between two organisms in which one (the parasite) lives on, off or at the expense of the other (host)
define helminth
multicellular parasitic worms that include flukes, tapeworms, and roundworms
define protozoa
unicellular endoparasites that include flagellates, amoebas, malarial organisms
define arthropods
multicellular ectoparasites that include insects (lice, fleas) and arachnids (ticks, mites) that are carriers (vectors) of diseases
