This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Infection, Subject name: Medicine
[{'content': '"River blindness" is caused by: \nSelect and explain. \nA. Onchocera-Volvulus, B. Schistoma haematobium, C. Fasciola hepatica, D. Opisthorchis-viverrini', 'role': 'user'}, {'content': 'Answer: A \nExplanation: (onchocera - volvulus) Ref: 1327-HI7th)ONCHOCERCIASIS: (River blindness) is caused by the filarial nematode O valvulus* Pruritis and rash are the most frequent manifestations of onchocerciasis* Visual impairment is the most serious complication of onchocerciasis. The most common early finding is conjunctivitis with photophobia "Snow flake" opacies is frequent in younger patients.* Enlarged nodes may hand down in response to gravity ^hanging grom ") sometimes predisposing to inguinal and femoral hernias* Mazzotti test is a provocative technique* IVERMECTIN is the treatment of choice for onchocerciasis', 'role': 'assistant'}]