Onchocerca volvulus : Onchocerciasis or river blindness

Question 1

MOT for onchocerciasis

Answer 1

biting flies of the genus Simulium. These flies breed in well-oxygenated water. They dominately migrate to the subcutaneous tissue while some localize in fibrous cysts or nodules containing worms over a boney prominence

Question 2

Pathogenesis of onchocerciasis

Answer 2

TARGET ORGANS ARE THE EYES AND SKIN.
*Eosinophils,neutrophils, and macrophages are cell types for forming microabscesses and normal collagen is replaced by scar tissue

Question 3

Clinical features of onchocerciasis

Answer 3

Early : itchy ,hyperpigmentation ,papular rash

• late : patchy depigmentation
• Eye : punctate (snow flake ) ,keratitis
• Blidness from both posterior and anterior lesions

Question 4

Diagnosis

Answer 4

• Diethylcarbamazine (SE: severe itching, exacerbation of eye lesion, fever, hypotension, respiratory diseases rash )
• Ivermectin: has replaced DEC with fewer side effects
• Suramin : used for microfilaride , it is toxic and not routinely recommended
• Nodulectomy : Done on head nodules to reduce risk to eyes