parasitology 3

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Author:
akl273
ID:
195108
Filename:
parasitology 3
Updated:
2013-01-25 09:14:50
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parasitology
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Description:
Onchocerca volvulus and Wuchereria bancrofti
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    • Onchocera volvulus
    • river blindness
    • in Central/South America, Central Africa

    subcutaneous human filariasis
    • Simulium spp. 
    • vector for Onchocera volvulus 
    • (river blindness)
    • lay eggs/live near running water

    • bites near ankles in daytime
    • picks up L1 microfilariae from the skin
    • releases L3
  1. How does Onchocera volvulus cause pathology?
    • Wolbachia spp. bacteria
    • live symbiotically with Onchocera volvulus microfilariae (L1)
    • --> inflammation
    • Onchocercomata
    • adult Onchocera volvulus live here

    apathogenic
    • Onchocera volvulus microfilariae
    • on slide from skin snip

    -> diagnostic
  2. How is Onchocera volvulus diagnosed?
    • using skin snips
    • Onchocera volvulus only lives in skin
    • Papular dermatitis
    • very itchy

    due to Onchocerca volvulus
  3. What are the clinical manifestations of Onchocerca volvulus?
    Skin: puritis, papular dermatitis, Lichenification (lizard skin), depigmentation, dermal atrophy, hanging groin

    Eye: sclerosing keratitis --> blindness
    • skin atrophy
    • 2* to Onchocerca volvulus

    loss of elasticity of skin
    • hanging groin
    • 2* to Onchocerca volvulus

    loss of skin elasticity
    • depigmentation
    • 2* to Onchocerca volvulus
    • sclerosing keratitis
    • 2* to Onchocerca volvulus

    --> progressive blindness
    • Wolbachia bacteria
    • cause of pathology in Onchocerca volvulus

    live symbiotically with microfilariae (L1)
  4. How is Onchocera volvulus treated?
    • Ivermectin --> kills microfiliariae
    • Doxycycline --> kills Wolbachia
  5. How is Onchocerca volvulus controlled?
    • vector control (DDT)
    • Ivermectin (2x per year)
    • - blocks transmission
    • - adult Onchocerca volvulus lives for 16 years
  6. What is the difference between Onchocera volvulus in Africa vs. Americas?
    vectors in Americas kill microfilariae upon feeding
    • Wuchereria bancrofti
    • lymphatic filariasis
    • in South America, Africa, Eastern Asia
  7. How is Wuchereria bancrofti transmitted?
    • L1 microfilariae picked up by mosquito vector (**culex)
    • (nighttime feeding - microfilariae only found in blood at nighttime)

    L3 transmitted to humans

    • **in cook islands, Aedes mosquito feeds in daytime
    • Wuchereria bancrofti has adapted
  8. How does Wuchereria bancrofti cause pathology?
    • adult migrates to lymph nodes
    • damages lymphatics
    • symbiotic relationship with Wolbachia bacteria

    **not 2* to lymph obstruction
  9. How is Wuchereria bancrofti diagnosed?
    • Historically:
    • thick blood film to find microfilariae at night

    • Now: ICT (Immuno Chromographic Test)
    • --> female antigen test
    • Lymphatic filariasis
    • 2* to Wuchereria bancrofti

    --> lymphedema/elephantiasis
  10. What are some clinical manifestations of Wuchereria bancrofti?
    • Chyluria (lymph in urine) - early
    • hydrocele
    • lymphedema
    • elephantiasis
    • filarial fevers (acute inflammatory response)
    • Chyluria
    • 2* to Wuchereria bancrofti
  11. What is an advantage of ICT testing for Wuchereria bancrofti?
    can detect infection prior to end of PPP (13 months)
  12. How is Wuchereria bancrofti treated?
    • DEC
    • Ivermectin with Albendazole
    • DEC with Albendazole
    • --> clears microfilariae (stops transmission)

    surgery (for hydrocele)
  13. How is Wuchereria bancrofti managed?
    • hygiene against fungal infections
    • leg elevation
    • skin care
    • exercise

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