Parasitology- Arthropods Flashcards
One form of control of Arthropods is through repellants? What chemicals act as repellants?
DEET
Citronella
Dimethyl phthalate
Chlorinated hydrocarbons are a form of chemical control for Arthropods. What are some examples? How do they work and how long do they last?
DDT, lindane, dieldrin, endrin
Interfere with ion transport across axon membranes
Very persistent
How do organophosphates work?
What are some examples?
What is their period of activity?
Interfere with Ach-e activity.
Examples of OPs include:
Malathion, diazinon, trichlophon (bots), dichlorvos (flea collars), cythioate
24-48hr activity
What drug can be administered to reverse OP effects?
Atropine
What are carbamates?
Chemical used for control of Arthropods that act similarly to OPs (Ach-e)
Examples include: carbaryl, propoxur
Lasts for 4-6 weeks.
*note high resistance to these
What chemical inhibits mono-amine oxidase?
What is this chemical useful on?
Formamidines
Ticks and mites
Example: amitraz (used to treat demodex)
What are some examples of pyrethroids? How do they act and how long do they last?
Based off chemical in Chrysanthemum flowers.
Examples: cypermethrin, deltamethrin, cyhalothrin
Last 7-14 days
Growth regulators are used to control Lucilia cuprina. What are some examples?
Methoprene, cyromazine, diflubenzuron
Macrocyclic lactones act on which channels? What are their two major groups?
Glutamate gated chloride channels
- Avermectins (eg. Ivermectin, abamectin, selamectin)
- Milbemycin (eg. Moxidectin)
How long is the period of activity in neonicotinoids? What are some examples?
2-4 weeks
Fipronyl (frontline) and imidacloprid (advantage) and nitenpyram
What are some distinguishing characteristics of crustacean Arthropods? What are the three subclasses covered?
5 or more pairs of legs
Several body segments
Copepoda
Isopoda
Pentastomida
Lernea sp. (anchor worm) is a common parasite of aquarium fish. What class/ subclass is it in?
Class: Crustacea
Subclass: copepoda
What type of parasite is cyclops?
A free living intermittent parasite
What is argulus foliaceus?
A pathogenic copepod of aquarium fish
What are 2 examples of isopoda parasites? What are they?
Ectoparasites of marine fish and crustaceans
- Ourozeuktes owenii
- Conodiphilus imbricatus (tongue biters)
What are pentastomids? Give some examples?
Parasites of the Crustacea class that affect the respiratory system. NO APPENDAGES!!!!
eg. Linguatula serrata (treat with ivermectin), armillifer armillatus (reptiles)
What are some characteristics of lice (order: phthiraptera)?
Wingless Dorso-ventrally flattened Antennae with 3-5 segments Legs with claws Host and site specific
Lice are what type of parasites? (in terms of how long they stay on host and how often they need the host)
Obligate permanent
What are some identifying features of sucking lice (anoplura)? Compare this to biting lice.
Pointy narrow head (round broad head in biting lice)
Only on mammals (birds and mammals have biting lice)
These feed off blood or tissue fluids as opposed to epidermis and feathers.
What feature distinguishes the larvae of fleas?
Anal struts
What stimulates the rupture of the flea pupal case?
Vibrations
What arthropod is a vector of myxomatosis?
Spilopsyllus cuniculi (rabbit flea)
What vector transmits equine infectious anaemia?
Werneckiella equi (biting louse)
What louse is transmitted on riding or grooming equipment?
Haematopinus asini
What louse is often mistaken for a tick and transmits pox and swine fever?
Haematopinus suits
What are some host effects of poultry lice and how may they be treated?
Decreased egg production, feather loss, irritation, poor growth
Dust baths, vaporisers, aerosols
What are some identifying features of species in the sub-order nematocera?
= small flies
They have long and slender antennae
They are crepuscular
Larvae and pupae are aquatic
Which nematocera genus and species causes Queensland itch and bluetongue?
Culicoides brevitarsis (and wadai)
What vector causes river blindness?
Simulidae (simulium damnosum)
What does austrosimulium pestilens transmit? What else transmits this nematode?
Onchocerciasis gutturosa in cattle
Culicoides species (introduced eg. C. brevitarsis and wadai)
Where are lesions found in Queensland itch?
Tail, rump, back, poll, ears.
Caused by culicoides brevitarsis and wadai
What is an identifying feature of the psychodidae order? In Australia, what do they feed on?
Hairy wings
Reptiles and amphibians
Are also vectors of leishmania
Culicidae species are vectors of what?
Yellow fever, dengue, Zika, Ross river, equine encephalitis
What are control methods for flies, midges and mosquitos of nematocera sub-order?
Remove breeding sites
Repellants (citronella, deet)
Fly screens
What are some identifying features of the brachycera sub-order?
What are they vectors of?
Large
Slow
Painful bites due to large biting apparatus
Vectors for trypanosomes, anthrax, viruses, nematodes
What is the name of the spinose ear tick? In what countries is it found?
Otobius megnini
North America and Africa. Recently found in WA
What type of parasite are ticks?
Obligate, but most of their lifecycle is off the host
What is the position of the anal groove in ticks of the genus ixodes?
In front of anus
Which tick is a vector for babesia gibsoni?
What type of tick is it (in terms of number of hosts)?
What is a distinctive anatomical feature of these ticks?
Haemaphysalis longicornis (bush tick) 3 host tick
They have lateral projections on their palps
Rhipicephalus australis is found where?
What are it’s effects on the host?
How may it be treated/controlled?
Northern Australia, central and South America, SE Asia
Effects:
Hide damage, anaemia, decreased growth rate and milk production, anorexia, disease (babesia, anaplasma, theileria), irritation
Control: Fly traps Macrocyclic lactones Growth regulators (flurazurone) Spell paddocks Vaccines Breed (zebu cattle are more resistant)
What is a vector for babesia canis?
Rhipicephalus sanguineus
Where are the spiracles located in mites?
Between coaxe 3 and 4
Ornithonyssus spp. of mites are commonly known as what?
What effect do they have on the host?
Starling lice
Cause severe anaemia and reduced egg production
What is pneumonyssoides caninum?
Nasal mites of dogs
What is the canary lung mite called?
Sternostoma tracheacolum
Why is varroa destructor so damaging?
It sucks haemolymph and causes varroosis.
Gets into colony and feeds on bee pupae and then reproduces
Causes colony collapse disorder
In what genus of mites are only the larvae parasitic? What are these mites commonly called?
Trombicula
Harvest mites
What causes black soil in qld?
Trombicula sarcina
Are cheyletiella host specific? What is distinctive about these mites?
No. Have a host preference though
They have a hook/claw on their palp
What is a distinctive feature of astigmid mites?
Front pairs of legs well separated from hind legs
What are some animals, other than dogs, affected by sarcoptes?
Pigs, camels, wombats, ferrets
What is trixacarus caviae?
What about notoedres cati?
Sarcoptid mite of guinea pigs
Cats and rabbits
What causes scaly leg of poultry?
Knemidocoptes mutans
What sarcoptid mites fats thee beak and legs of psittacines?
Knemidocoptes pili
What is a common ear mite of dogs and cats?
How is treated and diagnosed?
Otodectes cynotis
Otoscope
Imadacloprid/selamectin
What causes “ear mange”? How is it treated?
Psoroptes cuniculi
Avermectins
What causes barn itch?
Chorioptes bovis (in cattle, sheep, goats and horses)
What are some factors which influence the development of anthelmintic resistance?
- polymorphism in nematode population
- initial frequency of resistance alleles
- number of genes involved
- fecundity and length of life cycle
- whether the resistance genes are dominant or recessive
- the treatment frequency
- refugia (pop of worms unexposed to anthemintics)
- pharmacokinetic profile of the drug
What are the four broad mechanisms of anthelmintic resistance?
- Reduced drug uptake
- Increased drug efflux
- Detoxification
- Altered target
What are some tests we can do for anthelmintic resistance?
- egg hatching inhibition using BZ
- tubulin binding assay using BZ (using radio-labelled drug to kill parasite)
- larval paralysis test using levamisole/ ML
- larval development test (Drenchrite test)
- faecal egg count reduction test
For a faecal egg count reduction test, how do we determine if resistance is present?
Resistance is present if there is less than 95% reduction or if the lower 95% confidence interval is less than 90
What are some ways in which we can manage anthelmintic resistance?
- Check timing and admin of drugs (dose, method, frequency)
- Pasture management
- Rotate between drugs
- Quarantine drenches for all introduced animals
What is the mode of action of benzimidazoles? What are some examples and what are they commonly referred to as?
In what animals are they useful and what for?
Mode: inhibits polymerisation of tubulin which is important for cytoskeletal structure and for nematode gut cells.
Examples: thiabendazile (primary), fenbemdazole and albendazole (tertiary)
Widespread resistance in sheep trichostrongyles
Cattle drenches use tertiaries.
Used in horses but not for cyathostomes
Menbendazole used in dogs and cats
What type of drug is levamisole? How does it work?
What is it effective against? In what cases should it not be used?
It’s a imidazothiazole. Acts as a cholinergic receptor agonist at synaptic and extra-synaptic nicotine’s Ach receptors leading to spastic paralysis
It’s effective against all GINs and lungworms but not effective against inhibited larvae. Temp and rain affect absorbance.
Should not be used in horses as it leads to excitement.
Give an example of a tetrahydropyrimidine anthelmintic. How do these drugs work and what are they effective against?
Morantel, pyrantel
Mode: depolarise motor end plays in muscle by acting on Ach receptors
Act on most GINs but not lungworms and no effect on inhibited larvae
If nematodes in a sheep were resistant to levamisole, would they also be resistant to morantel?
Yes. But if resistant to morantel, still susceptible to levamisole
Describe the life cycle of simuliidae species (black flies). What might they transmit?
Aquatic life cycle. The larvae are carnivorous and eggs can survive in sand for around 2 years. They often develop following a flood.
Transmits onchocerca guttorosa of cattle and onchocerca volvulus of man.
Is myrantel used in dogs and cats?
No, pyrantel is used instead
How do macrocyclic lactones work?
What are they effective against?
They are GABA receptor agonists that bin with high affinity to a glutamate-gated chloride channel leading to flaccid paralysis. They’re effective against all GINs and arthropods but not against cestodes or trematodes
What is the preferred ML used in horses? Why?
Moxidectin is preferred over ivermectin as it kills up to 70% more inhibited cyathostomes
What are a couple of examples of organophosphate anthelmintics? How do they work?
Napthalophos, dichlorvos
They inhibit acetylcholinesterase leading to spastic paralysis. (Used only in sheep)
What is piperazine (diethylene diamine)? How does it work?
It’s a heterocyclic compound that acts as an agonist of GABA receptors leading to flaccid paralysis.
What is Closantel and how does it work? What is it used for?
It is a salicylanilide that interferes with the electron transport chain and uncouple oxidative phosphorylation. it is a narrow spectrum anthelmintic with a low safety index (5).
It is the drug of choice for Haemonchus in sheep. It is also effective against hookworms but is rarely used.
How does emodepside work?
Binds to iatrophilin recepetors and causes flaccid paralysis
What is the most recent class of anthelmintic drug on the market? How does it work?
Monepantel (an amino-acetonitrile derivative. It is a nematode specific nicotinic Ach receptor subunit agonist that causes spastic paralysis.
Which anthelmintic drug is particularly effective against the lungworm Dictyocaulus spp.?
Derquantel (nicotinic antagonist causing flaccid paralysis)
What is an appropriate deworming regimen for pups dogs and pregnant bitches?
Pups:
Treatment every 2 weeks prior to weaning
Treatment every 4 weeks after weaning
Treatment every 3 months after 6 months of age
Bitches:
Fenbendazole @50 mg/kg/day from 3 weeks prepartum to 2-15 days postpartum (time when most encysted larvae are activated)
What is the best way to treat gasterophilus species?
Organophosphates (eg, dichlorvos/ trichlorphon) or MLs (ivermectin/ moxidectin) during winter when flies are absent
What is a distinguishing feature of stomoxys calcitrans? What species does it affect?
Long piercing mouthparts.
Affects horses and dogs
= stable fly
What species does haematobia exigua feed on?
What is it a vector of? What other fly transmits this pathogen?
Cattle, buffalo, horse and dogs
Vector of trypanosoma evansi (melophagus ovinus- the sheep ked- also transmits this Protozoa) and the nematode stephanofilaria sp.
What are the effects of the sheep ked melophagus ovinus?
What is it’s lifecycle like?
Anaemia
Ricky wool
Trypanosoma
It lives in wool, pupal case attaches to wool, they hatch in 19-36 days and live for 4-5 months in wool
Which fly is responsible for oral myiasis? Is it in Australia? How can it’s larval stages be identified?
Chrysomya bezziana= Blue blowfly. Not in Australia.
Larval stages have bands of spines on each segment (like the bracelet)
Which lifecycle stage is infective for the lungworm oslerus osleri?in what species of animal is this worm found?
L1 is infective
Dogs 🐕
Besides haemonchus females, what other worms have a barbers pole appearance?
Angiostrongylus vasorum (lungworm of dogs) Angiostrongylus cantonensis (lungworm of rats)
How does the lifecycle of angiostrongylus vasorum differ to a normal lumgworm lifecycle?
Eggs are released pulmonary artery. Snails are IHs
What are the three gasterophilus species learnt? How may they be distinguished from each other?
G. intestinalis (common bot)
-eggs are yellow, laid anywhere on front of body, hatch when licked, larvae are red in stomach with double body spines
G. nasalis (throat not)
-eggs are pale, laid between mandibles, hatch spontaneously, larvae are yellow in duodenum with single body spines
G. haemorrhoidalis (nose bot)
-eggs are black, laid around lips and hatch spontaneously
What tick causes Lyme disease?
Ixodes scapularis
