Onchocerca Volvulus via female blackfly. Black flies, black skin nodules, "black sight" (aka Blindness). Question stem here describes the black nodules seen in Onchocerca.

SKETCHY https://www.google.com/url?sa=i&source=images&cd=&ved=2ahUKEwjQy9nft4fmAhUiCTQIHXh6BZEQjRx6BAgBEAQ&url=https%3A%2F%2Fquizlet.com%2F348275903%2F52-tissue-nematodes-dracunculus-medinensis-wuchereria-bancrofti-onchocerca-volvulus-toxocara-canis-loa-loa-flash-cards%2F&psig=AOvVaw2G9ehu-3FpT74t1v5_W2Ut&ust=1574842527097175

FLY GUY IN THE BACK Stains on the lab coat and pants --> black fly bites human host and the larvae burrow down into the host and make microfiliarial that come back out making hyper and hypopigmented spots. Human hand covering eyes --> causes river blindness Stray pink granules --> eosinophilia Microscope --> microfilaria on skin biopsy under microscope No dumping drains to river - Ivermectin for treatment

Reading microfilariae reminds me of three things. all from sketchy.

1. Loa Loa --> Deer flies --> subcutaneous nodules and larva crossing eye.
2. Onchocerca volvulus --> black fly --> deposits larva in skin which mature into adults producing microfilariae causing scattered puritiic papules and potentially eye blindness.
3. W. Bancrofti: this is due to mosquitos and causes elephantiasis. Also has microfiliariae.

Honestly, I was looking for deer fly. But culex mosquito is west nile, reduviid is chagas. I think everyone knows ixodes and body louse is not this.

There were 3 key things you needed to spot to lead you to Onchocerca. 1) little dude is from Congo 2) He's asymptomatic except for the skin nodules 3) the biggest key here was the presence of the microfilariae from the skin nodule

probably only 2 parasites are related to nodules: 1. trichinella spiralis: muscle mass, muscle ache, systemic symptoms 2. onchocerca volvulus: skin nodules, without significant systemic signs until blindness

NOTE: Microfilaria:

Microfilariais an early stage in the life cycle of certain parasitic nematodes in the family Onchocercidae.--wiki

For Pictures: https://emedicine.medscape.com/article/1109409-clinical#b2