Loa loa

This article is about the parasite. For the disease, see Loa loa filariasis.

Loa loa
Loa loa microfilaria found in blood film.
(Giemsa stain)
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Nematoda
Class: Chromadorea
Order: Rhabditida
Family: Onchocercidae
Genus: Loa
Species:
L. loa
Binomial name
Loa loa
(Cobbold, 1864)
Synonyms
  • Dracunculus loa Cobbold, 1864[1]
  • Filaria loa (Cobbold, 1864)

Loa loa is a filarial (arthropod-borne) nematode (roundworm) that causes Loa loa filariasis. Loa loa actually means "worm worm", but is commonly known as the "eye worm", as it localizes to the conjunctiva of the eye. Loa loa is commonly found in Africa.[2][page needed] It mainly inhabits rain forests in West Africa and has native origins in Ethiopia.[3] The disease caused by Loa loa is called loiasis and is one of the neglected tropical diseases.[4]

L. loa is one of three parasitic filarial nematodes that cause subcutaneous filariasis in humans. The other two are Mansonella streptocerca and Onchocerca volvulus (causes river blindness).[5]: Table 1 

Maturing larvae and adults of the "eye worm" occupy the subcutaneous layer of the skin – the fat layer – of humans, causing disease. The L. loa adult worm which travels under the skin can survive up to 10–15 years, causing inflammations known as Calabar swellings. The adult worm travels under the skin, where the female deposits the microfilariae which can develop in the host’s blood within 5 to 6 months and can survive up to 17 years. The young larvae, or microfilariae, develop in horseflies of the genus Chrysops (deer flies, yellow flies), including the species C. dimidiata and C. silacea, which infect humans by biting them. After bites from these infected flies, the microfilariae are unique in that they travel in the peripheral blood during the day and migrate into the lungs at night.[6]

  1. ^ Cobbold, T. S. (1864). Entozoa, an introduction to the study of helminthology, with reference more particularly to the internal parasites of man. London: Groombridge and Sons. doi:10.5962/bhl.title.46771.
  2. ^ Schmidt, Gerald et al. "Foundations of Parasitology". 7th ed. McGraw Hill, New York, NY, 2005.
  3. ^ Thomson, MC; Obsomer, V; Dunne, M; Connor, SJ; Molyneux, DH (2000). "Satellite mapping of Loa loa prevalence in relation to ivermectin use in west and central Africa". The Lancet. 356 (9235): 1077–1078. doi:10.1016/s0140-6736(00)02733-1. PMID 11009145. S2CID 11743223.
  4. ^ Metzger, Wolfram Gottfried; Mordmüller, Benjamin (April 2014). "Loa loa—does it deserve to be neglected?". The Lancet Infectious Diseases. 14 (4): 353–357. doi:10.1016/S1473-3099(13)70263-9. PMID 24332895.
  5. ^ Hermida Mandanas, Joshua Angelo (2021). "Lymphatic Filariasis: An Immunologic Perspective". EMJ Allergy & Immunology. 6 (1): 71–78. doi:10.33590/emjallergyimmunol/20-00252.
  6. ^ Turkington, C., & Ashby, B. (2007). Encyclopedia of Infectious Diseases. New York: Facts on File.