This excerpt/powerpoint presentation provides a basis for understanding the second most leading infectious cause of blindness world over

1. Onchocerciasis/river
blindness
Chemangei arap'musiwa

2. Overview
• Definition
• Etiology
• Epidemiology
• Pathogenesis
• Clinical presentation
• Differentials
• Complications
• Investigations/tests
• Management

3. Definition
• Onchocerchiasis is a condition resulting from
infection with the parasite onchocerca volvulus
• This parasite is transmitted by a blackfly of the
genus simulium(has avidity for fresh flowing water
e.g rivers)
• Breed and reside along rivers and streams

4. Epidemiology
• This condition is endemic in parts of tropical
africa,central and south america and also some
parts of Middle East e.g Yemen etc
• No predilection for sex or age group

5. Etiology
• The disease is a manifestation of the adult and
microfilarial stage of the parasite.
• Coinfection with wolbachia bacteria plays an
endosymbiotic role
• Coinfection with loa loa is lethal.

6. Pathogenesis
• The microfilariae mature into lavae in the gut of the
simulium fly
• The lavae are introduced into human's bloodstream
during the fly's next meal
• Onchocerca larvae are then transported throughout
the body but predominantly eyes and skin where they
mature into male and female adults
• After fertilisation,the resultant microfilariae circulate in
the bloodstream only to be picked by the blackfly on
it's next meal.The cycle recurs.

8. Clinical features
• Itching
• Subcutaneous nodules/onchocercomata
• Hanging groin
• Lymphadenopathy
• Lichenification
• Sowda
• Onchodermatitis
• Weight loss
• Myalgias

9. Cont.....
• Blurred vision
• Sclerosing keratitis
• Iridocyclitis
• Chorioretinitis
• Optic neuritis
• Glaucoma
• #River blindness
• Itchy, red and discharging eyes

10. Differentials
• Loa loa infection
• Hypersensitivity reaction
• Food allergy
• Filariasis
• Vitamin A deficiency

11. Complications
• As mentioned before
• Seizures
• Nakalanga syndrome
• Nodding disease
• Blindness
• Death etc .

12. Investigations
• Skin snip and biopsy
• Serology I.e ov16 antigen test
• Tears and urine for ov27 antigens
• ELISA
• PCR
• DEC(diethylcarbamazine) and mazzoti reaction
• Ultrasound scan
• Slit lamp examination

13. Management
• Prevention by mass prophylaxis of high risk
individuals with ivermectin
• Elimitation of blackflies
• Inpatient treatment requires 150mcgs of
ivermectin 3monthly
• Combination with doxycycline/minocycline
• Moxidectin

14. References
• Essentials of opthalmology(Neil.J.Friedman)
• Davidson textbook of clinical medicine
• World Health Organisation