Parasitic arthropods contd'

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Parasitic arthropodscontd.
Jo Hamilton Parasitology BS31820
6-14mm
5-7mm
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(c). Flies - as vectors.

• Family Psychodidae sandflies.
• Vectors of Leishmania - protozoa.
• Cutaneous leishmaniasis
• L. tropica - Old World.
• L. mexicana - New World.
• Mucocutaneous leishmaniasis (espundia) - L.
  braziliensis.
• Visceral leishmanisis (kala azar) - L. donovani.

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(c). Flies - as vectors

• Family Simuliidae - Blackflies.
• Simulium damnosum - vector in Africa.
• Simulium ochraceum - vector in New World.
• Vector Onchocerca volvulus (river blindness).
• In Australia Simulium spp. infect cattle O.
  gibsoni economic loss.

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(c). Flies as vectors

• Family Glossinidae, genus Glossina tsetse
  flies.
• Hosts vectors of trypanosome protozoans.
• Trypanosoma brucei species complex.
• Sub-saharan Africa.

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(d). Hemipterans.
Up to 2.5cm

• Class Insecta. Order Hemiptera.
• Parasitism in 2 lineages.
• Mouthparts - piercing/sucking.
• 1. Family Reduviidae.
• Subfamily Triatominae.
• 2. Family Cimicidae - bedbugs.

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Economic impact of vector-borne diseases.

• Morbidity mortality.
• Human health productivity.
• Losses to draught pack animals.
• Milk meat yields.
• Damage to skins hides wool quality.
• Losses in agriculture, companion animals sport
  animals.
• Fertiliser?

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Advances in the control of Ctenocephalides felis
(cat flea) on cats and dogs.

• Michael K. Rust.
• Trends in Parasitology 21232-236.

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Introduction

• Cat flea
• Important ectoparasite - cats dogs.
• Topical oral insecticides revolutionised
  control.
• Eliminate need to treat environment.
• Reduces flea allergic dermatitis (FAD).
• Insecticidal resistance?
• Extend longevity of these new compounds.

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Flea control on cats dogs

• Cat flea, Ctenocephalides felis.
• Most problematic.
• Discomfort
• Pets owners (parasite psychosis)
• Vectors
• tapeworm
• Cause flea allergic dermatitis (FAD).
• Role in feline leukaemia cat scratch fever?
• Annual control expenditures
• gtUS1bn USA. 1.1billion euro in Western Europe.

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Flea control on cats dogs

• Revolutionary control products in past 10 years
• systemic topical
• Eliminates need to treat environment
• Only need to treat animal.
• Determining efficacy of treatment in field
  difficult.
• Comb - 5 mins estimate flea population.
• Flea distribution - head neck.

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Questions?
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Flea biology

• Where do flea infestations originate?
• How do animals that live indoors get infected?
• Reinfestation after successful treatment?
• Feral animals reservoirs?
• Lack of evidence.
• Feral animals infected by fleas from companion
  animals.
• Overlapping territories transfer cycle.
• Preventative use control products for pets
  exposed to outdoors.

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Flea biology

• Immature fleas
• Require RH gt50.
• Temp 4 -35OC.
• Feed on dried blood yeast
• Adult flea faecal blood
• Cannibalism of non-fertile eggs
• Adult male female BSIs
• Mating
• On host
• Male - fully fed 11min
• Female fully fed 25 min

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Questions?
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Host-targeted therapy

• Oral / topical treatments.
• 1995 registration of lufeneron.
• Avermectins
• Fipronil
• Imidacloprid
• Nitenpyram
• Pyrethroids pyrethrins
• Insect growth regulators
• Juvenile-hormone analogues (JHAs)
• Insect developmental-inhibitors (IDIs)

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Questions?
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Flea allergic dermatitis (FAD) studies.

• Caused by hypersensitivity to flea saliva
  components
• Individuals varying severity.
• New concept oral topicals can manage FAD.
• If treatment prevents feeding no allergen.
• Continuous or episodic feeding FAD.
• Examples of compounds that inhibit feeding.

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Questions?
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Insecticide resistance.

• Pest status cat flea
• Extend longevity of current treatments.
• Monitoring programmes - insecticidal resistance.
• Need bioassays adults larvae.
• Background levels resistance susceptibility.
• No universally susceptible strains
• Use lab strains for baseline
• Maintenance distribution of lab strains for
  research

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Insecticide resistance.

• Cat fleas tend to develop resistance.
• Limited reports of resistance to new compounds
• Cottontail strain
• Fieldcollected strain

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Insecticide resistance.

• Rdl gene mutations associated with resistance
• Cyclodienes
• Fipronil
• PCR-based diagnostics
• Resistance in a UK field population
• Promising technique for monitoring potential
  resistance.

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Questions?
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Concluding remarks.

• Challenge
• develop control strategies that conserve these
  therapies.
• Monitoring
• Knowledge application
• Stewardship
• Vets pet owners

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Questions?