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parasitology 3
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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
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
How is Onchocera volvulus diagnosed?
using
skin snips
Onchocera volvulus only lives in skin
Papular dermatitis
very itchy
due to Onchocerca volvulus
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)
How is Onchocera volvulus treated?
Ivermectin --> kills microfiliariae
Doxycycline --> kills
Wolbachia
How is Onchocerca volvulus controlled?
vector control (DDT)
Ivermectin
(2x per year)
- blocks transmission
- adult Onchocerca volvulus lives for 16 years
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
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
How does Wuchereria bancrofti cause pathology?
adult migrates to
lymph nodes
damages lymphatics
symbiotic relationship with
Wolbachia
bacteria
**not 2* to lymph obstruction
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
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
What is an advantage of ICT testing for Wuchereria bancrofti?
can detect infection prior to end of PPP (13 months)
How is Wuchereria bancrofti treated?
DEC
Ivermectin with Albendazole
DEC with Albendazole
--> clears
microfilariae
(stops
transmission
)
surgery (for hydrocele)
How is Wuchereria bancrofti managed?
hygiene against fungal infections
leg elevation
skin care
exercise
Author
akl273
ID
195108
Card Set
parasitology 3
Description
Onchocerca volvulus and Wuchereria bancrofti
Updated
2013-01-25T14:14:50Z
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