Parasite
Loa loa
African eye worm with Calabar swellings
LOH-uh LOH-uh
High-yield clue
Adult worm crossing the subconjunctiva plus transient Calabar swellings; microfilariae show diurnal periodicity matching the daytime-biting deerfly.
Overview
A filarial nematode transmitted by Chrysops deerflies (mango flies) whose adults migrate through subcutaneous tissue, the classic 'eye worm' of loiasis.
Classification
- Nematode (filarial worm)
- Adults migrate in subcutaneous tissue
- Sheathed microfilariae
- Transmitted by Chrysops deerfly
Lab & identification clues
- Sheathed microfilariae on midday (diurnal) blood smear
- Adult worm visible crossing the eye
- Giemsa-stained blood smear vocabulary
Associations
- Chrysops (deer/mango fly) vector, daytime biting
- Diurnal periodicity of microfilariae
- Calabar swellings (transient subcutaneous edema)
- West/Central African rainforest distribution
Commonly confused with
- Wuchereria bancrofti
- Onchocerca volvulus
Frequently asked questions
What is Loa loa?
A filarial nematode transmitted by Chrysops deerflies (mango flies) whose adults migrate through subcutaneous tissue, the classic 'eye worm' of loiasis.
What are the lab clues for Loa loa?
Lab clues for Loa loa include Sheathed microfilariae on midday (diurnal) blood smear, Adult worm visible crossing the eye, and Giemsa-stained blood smear vocabulary.
What is Loa loa commonly confused with?
Loa loa is commonly confused with Wuchereria bancrofti and Onchocerca volvulus.
Original student-study summary. Sources checked: OpenStax Microbiology 2e, NCBI Bookshelf Medical Microbiology, and CDC topic pages where applicable; reviewed 2026-06. Educational only; no diagnosis, treatment, dosing, or specimen-handling guidance.