A 45-year-old fisherman from coastal Odisha presents with painless subcutaneous nodules over the trunk and extremities, and night blindness. Skin snip microscopy is performed. This test is used for diagnosis of:
- A Loiasis (Loa loa)
- B Bancroftian filariasis (Wuchereria bancrofti)
- C Dracunculiasis (Dracunculus medinensis)
- D Onchocerciasis (Onchocerca volvulus) ✓
Explanation
Skin snip microscopy (a bloodless skin biopsy placed in saline to allow microfilariae to emerge) is the classical diagnostic method for onchocerciasis (river blindness) caused by Onchocerca volvulus. The microfilariae of O. volvulus are found in the dermis, not blood — distinguishing it from other filarial infections. The subcutaneous nodules (onchocercomas) contain adult worms. Night blindness progressing to corneal opacification ('snowflake keratitis') is the hallmark ocular complication. Loa loa is diagnosed by blood smear at mid-day; W. bancrofti by nocturnal blood smear.
Reference: Ananthanarayan & Paniker's Textbook of Microbiology, 11th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.