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MCQs in Tropical Medicine

Rob Skelly DTM+H FRCP

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Answer 89 - Onchocerciasis

The following are recognised features of onchocerciasis:
True a. keratitis
False b. diarrhoea
True c "hanging groin"
False d. Calabar swelling
True e. eosinophilia

Causative organism: Onchocerca volvulus
Vector: Simulium fly
Distribution: equatorial Africa, Yemen, S.America
Other hosts: Adult worms are only found in humans

Life cycles:Adult worms live in subcutaneous tissue. They may also be found in fibrotic nodules. Female worms produce many microfilariae which may be taken up by Simulium when it bites. After several weeks in the fly the microfilariae develop into infective larvae.

Clinical features:
"hanging groin"
Retinal changes

Treatment: Ivermectin

Copyright: Rob Skelly 2006