This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Ocular Manifestations, Subject name: Ophthalmology
River blindness is caused by : 
Select and explain. 
A. Drinking river water without boiling., B. Oncocerca volvulus, C. Toxoplasma canis, D. Glaucoma
B: Oncocerca volvulus
Answer: B: Oncocerca volvulus 
Explanation: Ans. is 'b' i.e. Onchocerca volvulus Onchocerca volvulus is transmitted by Simulium damnosum, a black fly* that breeds in areas of rapidly flowing streams thus the term 'river blindness9T/t by Ivermectin*