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72 Cards in this Set

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What are the 5 major groups of parasites?
- protists
-nematodes
-trematodes
-cestodes
-arthropods
What is a nematode?
a "round worm"
What is a trematode?
a "fluke" (flat worm)
What is a cestode?
a "tape worm" (flat worm)
Of the word "Arthropod", what does "arthros" and "podos" mean?
"Arthros" = joint
"Podos" = foot
What are the 3 classifications of arthropods?
- Crustateans
- Insects
-Arachnids
What are the features which are used to class the 3 classes of arthropods?
Number of legs
Which class of Arthropod has 4 pairs of legs?
Arachnids
How many pairs of legs does a Crustacean have?
Five
Which class of Arthropod has 3 pairs of legs?
Insects
What are the features of Arthropods that hold veterinary significance?
- The exoskeleton (cuticle)
- The muscle system (attached to exoskeleton)
- The circulatory system (open, blood is free in haemocoel)
What is the basic outline of an Arthropod digestive system?
mouth --> intestine --> rectum
What is the most significant feature of an Arthropod's digestive system, from a veterinary POV?
The Salivary glands
Why are the salivary glands of an Arthropod significant from a veterinary POV?
Because diseases can be transmitted from Arthropod to host via the salivary glands (when they bite/eat/feed on host)
What part of the Arthropod is the most common target of drugs?
The nervous system
What are the two types of respiratory systems on arthropods?
- gills in aquatic arthropods
- tracheal system (holes in the exoskeleton) in terrestrial arthropods
What is the simple method by which one could kill an arthropod by targeting its respiratory system?
Cover it will oil
What are the two types of parasitism?
- Ectoparasites (lives inside body)
- External Parasites (lives outside body)
What is an" obligate parasite"?
A parasite that MUST have a host (eg: fleas)
What is a "facultative parasite"?
A parasite that can survive without a host (eg: flies)
What is a "Permanent Parasite"?
A parasite that must be on a host at ALL TIMES (eg: lice)
What is an "Intermittent Parasite"?
A parasite which visits its host(s) periodically (eg: mosquetos - only females feed on hosts, males eat nector)
In reference to an Arthropod's life cycle, what is meant by the term "mault"?
To shed the outer layer of the body
In reference to an Arthropod's life cycle, what is meant by the term "instar"?
The stage in the insects life between two maults.
Define Metamorphoses:
The name given to the changes that take place during the insect's life as it turns from an immature form to an adult.
What is the most common form of pathogenicity of arthropods:
That they will act as vectors for viruses, bacteria or other parasites.
What are the 3 major mechanisms of chemical control of arthropods?
1) repellents
2) Chemicals acting on the nervous system
3) Growth Regulators
Name the 4 most common types of Repellents used:
- DEET
- dipropyl isocinchomeronate
- piperonyl butoxide
- citronella
Name the 3 types of Chemicals used to act on the nervous system:
- DDT
- Lindane (gamma benzene hexachloride
- Dieldrin, Endrin
What were Chlorinated Hydrocarbons used for, and why were they banned?
-Used as an effective insecticide for mass field spraying
-work on the nervous system to cause paralysis
- It does not break down, so accumulation can occur up food chains.
What is the method of organophosphates in acting on the nervous system of an Arthropod?
Blocks acetylcholine esterase (Ach) therefore prevents neural messages from being transferred across the synapse = paralysis
Why are organophosphates commonly used?
- effective method of paralysis
- breaks down quickly so cannot accumulate up the food chain and harm non-target organisms
- can be treated with Atropine to reverse (if necessary)
What are the two administration methods of organophosphates?
- topical (body surface)
-oral
How do Carbamates act as an insecticide?
via similar action to organophosphate - interfering with the nervous system and causing paralysis.
(lasts 4-6 weeks, longer than organophosphates)
What is the most common use of carbamates as an insecticide and why?
Flea control - because it can persist for 4-6 weeks.
How do Formamidines cause paralysis in arthropods?
by inhibiting mon-amine oxidase
What is "Amitraz" an example of, and what is it used for?
- example of a Formamidine
- used for treatment of ticks and demodentric mange in cattle
Pyrethroids cause paralysis in arthropods. What is their method of action?
Blocks sodium channels of axons in nervous cells so that action potentials cannot take place, therefore a nervous message cannot be sent.
What is the difference between "Pyrethroid" and "Pyrethrin"?
Pyrethoids is taken from Pyrethin and concerntrated
- Pyrethin is originally derived from the chrysanthemum flowers.
Is the toxicity of Pyrethoids high or low to vertebrates?
low - except to fish.
How long do Pyrethroids last for?
only 24 hours
How would you administer a Pyrethoid?
via topical (surface) administration
What do Macrocyclic lactones do, and how do they work?
- cause paralysis
- act on glutamate-gated chloride channels to disrupt ability to produce action potentials
What types of Parasites are Macrocyclic lactones highly effective against?
Arthropods and nematodes
Neo-nicotinoids (and others) cause paralysis. How?
by blocking receptors
What is a common product which Fibronil (a Neo-nicotinoid) is found in?
Frontline - flea control
How are Neo-nicotinoids admmistered, and what is their toxicity to vertebrates?
- topical administration
- non-toxic
Imidacloprid:
What class of chemicals that cause paralysis does it belong to?
Neo-nicotinoids
Imidacloprid:
How does it cause paralysis?
By blocking nicotinic receptors (found in "Advantage" products)
Imidacloprid:
When applied topically, how does it work to treat ectoparasites?
By distributing through the skin and not entering the tissue/ blood beneath.
Ivermectin:
What class of chemical does it belong to?
Macrocyclic lactones
- acts on glutamate-gated chloride channels
Ivermectin:
When applied topically, how is it distributed?
Through the dermis and into the blood.
How do Growth Regulators work?
By interfering with growth, moulting, and egg laying
How are Growth Regulators administered, and what is their toxicity?
- oral or topical
- low toxicity
Why do Growth regulators work (their mechanism)?
Because they are analogues of insect growth hormones, therefore mimic the hormones and can interfere with their actions.
Why are Growth Regulators used less than Repellents or chemicals that interfere with the nervous system?
Because they do not kill the arthropods immediately but instead work to inhibit their reproduction - therefore a population controller.
- not popular as public want to see "instant kill"
What are the 3 subclasses of Parasitic Crustaceans?
- Copepoda (ecto-parasites of fish)
- Isopoda (ecto-parasites of fish)
- Pentastomida (internal parasites of reptiles, birds, mammals)
What crustacean sub class does "Cyclops" belong to?
Copepoda
What is a common Crustacean Copepoda that is common on aquarium fish?
Lernea sp. (anchor worm)
What Custacean subclass does "Ourozuektes owenii" belong to?
Isopoda
Where is the Crustacean Isopoda "Ourozuektes owenii" found in marine fish?
within the body cavity
What Crustacean sub-cass does "Conodophilus imbracatus belong to?
Isopoda
Why is Conodophilus imbricatus" called "tongue bitter"?
because it consumes the fish's tongue and then latches on and takes the place of the tongue, acting like a tongue.
Where are the Crustacean sub-class "Pentastomida" mainly found?
In the respiratory system of birds, mammals, and reptiles
Asides from being a sub-class of the Crustacean group, what do Pentastomida look more like?
Worms, with a hard exterior
What is the structure of the Pentastomida's "head" (Crustacean group)?
two hooks (legs) on either side of mouth
Where is the Linguatula serrata (Crustacean - Pentastomida) found?
found in the nasal cavity of dogs
The Linguatula serata ("tongue worm") (Crustacean - Pentastomida) has an indirect life cycle. What are the brief steps of this life cycle?
- adult in the nasal cavity of the dog
- eggs laid and travels in mucous down nasopharynx to pharynx and swallowed
- eggs passed out in faeces
- eggs distributed into soil
- eggs and soil particles eaten by grazing sheep / rabbits
- lava activated in sheep/rabbits and move into flesh
- raw flesh containing lava of sheep / rabbits eaten by dog
- lava matures and crawls up stomach, oesophagus and pharynx of dog to nasal cavity.
- life cycle repeats
What are the clinical signs of "Linguatula serrata" (Crustacian - Pentastomida):
nasal discharge and severe irritation
How would you diagnose the presence of Liguatula serrata in a dog?
finding the eggs in faeces
What drug would you administer for the treatment of Linguatula serrata?
ivermectin
What is a key feature of a Pentastome of reptiles(Crustacean) indirect life cycle?
They use small mammals or other arthropods as intermediate hosts