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1-5mm. Parasitic arthropods cont’d. Jo Hamilton Parasitology BS31820. 6-14mm. 5-7mm. (c). Flies - as vectors. Family Psychodidae – sandflies. Vectors of Leishmania - protozoa. Cutaneous leishmaniasis: L. tropica - Old World. L. mexicana - New World.

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Parasitic arthropods cont d

1-5mm

Parasitic arthropodscont’d.

Jo Hamilton

Parasitology

BS31820

6-14mm

5-7mm


(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.


(c). Flies - as vectors

Family Simuliidae - Blackflies.

  • Simulium damnosum - vector in Africa.

  • Simulium ochraceum - vector in New World.

  • Vector Onchocercavolvulus(‘river blindness’).

  • In Australia Simulium spp.infect cattle O. gibsoni – economic loss.


(c). Flies as vectors

Family Glossinidae, genus Glossina – tsetse flies.

  • Hosts & vectors of trypanosome protozoans.

  • Trypanosomabrucei species complex.

  • Sub-saharan Africa.


D hemipterans
(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.


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?


2-8mm

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

Michael K. Rust.

Trends in Parasitology21:232-236.


2-8mm

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.


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

    • >US$1bn – USA. 1.1billion euro in Western Europe.


2-8mm

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.


2-8mm

Questions?


2-8mm

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.


Flea biology

  • Immature fleas:

  • Require RH >50%.

  • 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



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)



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.



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


Insecticide resistance.

  • Cat fleas tend to develop resistance.

  • Limited reports of resistance to new compounds

    • “Cottontail” strain

    • Field–collected strain


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.



Concluding remarks.

  • Challenge:

    • develop control strategies that conserve these therapies.

  • Monitoring

  • Knowledge application

  • Stewardship

    • Vets & pet owners



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