## **Core Concept**
The question describes a clinical presentation suggestive of a parasitic infection, specifically **loiasis**, also known as African eye worm. This condition is caused by a filarial parasite.

## **Why the Correct Answer is Right**
The presence of subcutaneous, itchy nodules (often referred to as "Calabar swellings") that are firm, non-tender, and mobile, along with the finding of microfilariae and adult worms in skin scrapings, is highly suggestive of **Loa loa** infection. **Loa loa**, also known as the African eye worm, is a filarial parasite transmitted by the bite of a deer fly. The microfilariae are diurnal, meaning they are more commonly found in the peripheral blood during the daytime. The adult worms can be seen migrating under the skin or across the conjunctiva of the eye.

## **Why Each Wrong Option is Incorrect**
- **Option A:** *Wuchereria bancrofti* causes lymphatic filariasis, leading to conditions like elephantiasis, and does not present with subcutaneous nodules or the described findings in skin scrapings.
- **Option B:** *Brugia malayi* and *Brugia timori* are also filarial parasites but are more commonly associated with lymphatic filariasis and not typically with the subcutaneous migration of adult worms or the specific presentation described.
- **Option D:** *Onchocerca volvulus* causes onchocerciasis or river blindness, characterized by skin nodules (onchocercomata) that contain adult worms, but the microfilariae are found in the skin, not typically described as being accompanied by adult worms in skin scrapings in the way *Loa loa* can.

## **Clinical Pearl / High-Yield Fact**
A key clinical feature of loiasis is the **subcutaneous migration of adult worms**, which can be visually observed or extracted from the skin. This presentation, along with the presence of microfilariae in the blood (especially during the daytime) and the characteristic Calabar swellings, is crucial for diagnosing *Loa loa* infection.

## **Correct Answer:** . Loa loa