Intro to CAR Parasitology Flashcards
Define parasitism
Only one organism (parasite) benefits from the interaction to the detriment of the other (host)
Define mutualism
Organisms of different species both benefit from the interaction e.g. Honey bee & flowering plant
Define commensalism
Only one organism benefits from this association without causing harm to the second organism
Define hyperparasitism
Parasites of parasites
Define parasitoid
Parasites which kill the host at the end of their lifecycle
Define symbiosis
A close and prolonged interaction between organisms of different species
Define a facultative parasite
May survive in the absence if the host e.g. opportunistic
Define a obligate parasite
At some or all stages of life cycle cannot survive without host
Define an endo-parasite
Lives inside the host e.g. worms, protozoa
Define a ecto-parasite
Lives in/on the outer surfaces of the host e.g. Fleas, lice, tick, mites
Define a definitive host
The final host in which parasite sexual reproduction occurs
Define an intermediate host
The host in which parasite asexual reproduction occurs
Define a permissive host
An accidental host not usually used by parasite but still allows life cycle completion e.g., liver fluke (Fasciola hepatica) infection in humans
Define a non-permissive host
An accidental host in which the parasite cannot complete the life cycle. e.g., Toxocara infection in humans
Define a reservoir host
Host in which parasites can be maintained AND which is the source of infection for another host that we’re interested in (the ‘target’ host) BUT in parasitology also used to mean simply a large source of the parasite (eg paratenic hosts)
Define a paratenic host
Host not necessary for the lifecycle or development, but which can act as a ecological/epidemiological ‘dump’ (‘reservoir’) of the parasite and source of infection e.g. frogs for dog lungworm
Explain the principle of a mechanical vector
A vector which mechanically spreads a parasite: no parasite replication occurs so mechanical vectors are not hosts (but may be important to transmission)
Explain the principle of a biological vector
An intermediate host which is itself (usually) a parasite
e.g. mosquitoes transmitting malaria
Identify the portals of entry for parasites into the animal body
Ingestion (eg in food or water)
Skin penetration (eg hookworm larvae)
Skin inoculation by arthropod bite (‘vector’-borne protozoa)
Direct animal-to-animal contact (lice)
Trans-placental (vertical) (Strongyloides spp)
Sexual intercourse (Trichomonas spp)
Inhalation (Cytodites spp airsac mites in birds, Pneumonyssus spp pulmonary mites in primates)
Define a direct lifestyle of a parasite
Parasitic stages develope in/on host
E.g cattle lungworm
Define an indirect lifestyle of a parasite
Intermediate host(s) (different species) needed for the development of some stages of the parasite
E.g. Canine lungworm
What questions would be asked, during a diagnosis, to understand a parasites life cycle?
- Type of life cycle (direct or indirect)
- What’s the definitive host?
- What are the intermediate host? (if any, then it is indirect cycle)
- What is the infective stage to the host your are interested in?
- What are the routes of infection?
How does understanding a parasites life cycle help during diagnosis and treatment?
Help to understand pathology, clinical signs and diagnosis
Enable us to:
Determine an appropriate therapeutic ‘window’
Manage disease properly Protect other animals from cross-infection Protect people from zoonotic infections
Understand the basis of cardio-respiratory parasite control
Integrated parasite control
-Avoiding risky behaviour
-Hygiene & nutrition means good immune response to reduce risk
-Disrupting transmission ( treating intermediate hosts / not letting the animal eat faeces / washing toys)
-Treatment intervention (few vaccines for this area / drugs can lead to resistance and damage the non targeted species in the environment (poor environmental effects)
Give examples of parasitic phyla
nemathelminths
Understand the morphological features of round worms
‘Helminth’ is a general (rather than biological/taxonomic) term for endoparasitic ‘worms’ and worm-like creatures:
- Nematodes – (nematos = thread)
- Acathocephala – (akanthos = thorn)
- Platyhelminthes (platy = flat)
○ Cestodes – tapeworms
○ Trematodes – flukes
(monogeneans are ectoparasitic flatworms of fish)
