River Blindness Flashcards
What organism causes river blindness?
Onchocerca volvulus
What is the vector for river blindness?
Simulium black fly
Where do the adult onchocerca worms live?
In fibrous subcutaneous nodules called onchocercomas.
Normally on bony prominences: Africa-iliac crests, ribs, sit bones. S.America- scalp
Where do you find the onchocerca microfilariae?
Subcutaneous tissues
What are the dermal signs of river blindness?
Leopard skin Hanging groin Lizard skin Lichenification- Yemen and Sudan Onchodermatitis
What are the ocular manifestations of river blindness?
Itching, red, lacrimation Punctate keratitis Iritis-> glaucoma Optic atrophy Blindness
How do you diagnose onchocerca volvulus?
Bloodless skin snip (2-4 samples)
Slit lamp showing MF in anterior eye
DEC patch test
PCR on skin snips
What do the onchocerca volvulus microfilariae look like?
200 microm Globular head Unsheathed Tail tapers to point Nuclei don't extend to tip
How do you treat onchocerca volvulus?
Ivermectin annually for over 10yrs (map Loa Loa first with RAPLOA)
Doxycycline 6/52
Nodulectomy
How to you control and prevent river blindness?
Avoid being bitten- day biters
Insecticide spraying
Map onchocerca, if >20% +ve then MDA
How do you identify a black fly?
Cone shaped antennae
Long piercing mouthparts
Darker veination on the wing edge
What are the habits of the black fly?
Outdoor day biting
Live near flowing water/ rivers
What prevention schemes are in place for onchocerciasis?
ESPEN: MDA with ivermectin
- increase Tx towards 100% geographical coverage
- scale down stopping Tx once control achieved
- information systems for evidence based action
- improve use of donated meds
Where has onchocerciasis been eliminated?
Colombia
Mexico
Ecuador
Guatemala
