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Parasitic arthropods cont’d.

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.

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  1. 1-5mm Parasitic arthropodscont’d. Jo Hamilton Parasitology BS31820 6-14mm 5-7mm

  2. (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.

  3. (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.

  4. (c). Flies as vectors Family Glossinidae, genus Glossina – tsetse flies. • Hosts & vectors of trypanosome protozoans. • Trypanosomabrucei species complex. • Sub-saharan Africa.

  5. (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.

  6. 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?

  7. 2-8mm Advances in the control of Ctenocephalides felis (cat flea) on cats and dogs. Michael K. Rust. Trends in Parasitology21:232-236.

  8. 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.

  9. 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.

  10. 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.

  11. 2-8mm Questions?

  12. 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.

  13. 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

  14. Questions?

  15. 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)

  16. Questions?

  17. 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.

  18. Questions?

  19. 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

  20. Insecticide resistance. • Cat fleas tend to develop resistance. • Limited reports of resistance to new compounds • “Cottontail” strain • Field–collected strain

  21. 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.

  22. Questions?

  23. Concluding remarks. • Challenge: • develop control strategies that conserve these therapies. • Monitoring • Knowledge application • Stewardship • Vets & pet owners

  24. Questions?

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