Loa loa 2
Loa loa is the filarial the filarial
nematode (roundworm) species nematode (roundworm) species that that causes Loa loa filariasis. filariasis . It is commonl commonly y known known as the “eye worm” . Its geographic distribution includes Africa and India.[1]
Main article: Loa loa filariasis
L. loa is one of three parasitic filarial nematodes that cause subcutaneous subcutaneous filariasis in hum humans. ans. The The two two other filarial nematodes are Mansonella streptocer streptocerca ca and and (causes river blindness). blindness). Onchocerca volvulus (causes river
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Bio Bi ology
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Morp Morpho holo logy gy
Loa loa wormshavea wormshavea simpl simplee body body incl includi uding ng a head, head, body, body, and tail. tail. Males Males range range from rom 20mm 20mm to 34mm long and 350μm to 430μm wide. wide. Females Females range range from from 20mm to 70mm long and are about 425μm wide. [1]
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Diagno Diagnosis sis and treatm treatmen entt
The main methods of diagnosis include the presence of microfilariae in the blood, the presence of a worm in the eye, and the presence of skin swellings. Surgical removal removal of the worm worm can can easi easily ly be perf performed. ormed. The commo common n treattreatment for the disease is the use of the drug Ivermectin Ivermectin..[1]
Life Life cycle ycle
Three species involved in the life cycle include the parasite Loa loa, the fly vector, and the human host: [2] •
Patho Pathoge genes nesis is
Loa loa parasites infect human hosts by travelling from the entry entry site site throu through gh subc subcuta utaneo neous us tissu tissues es and causi causing ng inflammation in the skin wherever they travel. If a parasite stops in one place for a short period of time, the human host will suffer from local inflammation known as Calabar swellings. These are localized, tense, inflammatory pruritic pruritic subcuta subcutaneou neouss edema edema seen in joints joints of extremi extremities ties,, lasting for 1–3 days. They represent represent areas of angioedema resulting from from a host response to allergens released by the maturating worm and its metabolic products. [3] Calabar swellings often occur in the wrist and ankle joints but disappear as soon as the parasite begins to move again. Parasites can also travel through and infect the eye, causing the swelling of the eye. Common symptoms include include itching, joint pain, fatigue, and death. [1]
Maturing larvae Maturing larvae and and adults of the “eye worm” occupy the subc subcut utan aneo eous us laye layerr of the the skin skin – the the fat laye layerr – of huma humans ns,, causing causing disease. disease. The young young larvae larvae develo develop p in horseflies of the genus the genus Chrysops (deer (deer flies, yellow flies), including the species C. dimidiata and C. silacea, which infect humans by biting them.
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Disease
Ivermectin has become the most common antiparasitic agent used worldwide but can lead to residual microfilarial load when given given in the manageme management nt of loiasis. loiasis. High High microfilarial loads should be decreased by a course of iverme ivermecti ctin, n, a prolonged prolonged administ administrati ration on of albendazo albendazole, le, or cytapheresis sessions to prevent occurrence of serious adverse events, including fatal encephalopathy induced by dying microfilariae. Cytapheresis Cytapheresis is helpful helpful in decreasing decreasing very high microfilar microfilarial ial loads up to 75%. Diethyl Diethylcarb carbaamazine kills both microfilariae and adult worms but has more severe side effects and can be fatal.
A vect vector or fly bite bitess an inf infecte ected d huma human n host host and and inge ingest stss microfilariae. Microfi Microfilaria lariaee move move to the the fat fat body body of the the insect insect host. host. Microfilariae develop into first stage larvae, second stage, then third stage larvae. Third stage larvae (infective) (infective) travel to the proboscis of fly. An infected vector fly bites an uninfected human host and the third stage larvae penetrates the skin and enters human subcutaneous tissue.
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Larvae mature into adults, who produce microfilariae that have been found in spinal fluid, urine, peripheral blood, and lungs.
Ref Referen erence cess
[1] Schmidt, Gerald Gerald et al. “Foundations of Parasitology”. Parasitology”. 7th ed. McGraw Hill, New York, NY, 2005.
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[2] “Filariasis”. Parasites and Health. Center for Disease Control. [3] Rivière, E., Kerautret, J., Combillet, F., & Malvy, D. (2012). African Eye Worm. Journal Of Global Infectious Diseases, 4(2), 135-136. doi:10.4103/0974-777X.96782 •
Taxonomy Browser: Loa Loa. National Center for Biotechnology Information (NCBI).
REFERENCES
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Text and image sources, contributors, and licenses
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Text Loa loa Source: http://en.wikipedia.org/wiki/Loa_loa?oldid=656037586 Contributors: Mahongue, Discospinster, Arcadian, Trlovejoy, Bgwhite, Dysmorodrepanis~enwiki, Complainer, SmackBot, Edgar181, PamD, Sedmic, VolkovBot, Euryalus, Arjayay, Trabelsiismail, Addbot, Yobot, Jim1138, JavaMan, JimVC3, FrescoBot, Shintau, EmausBot, ZéroBot, Salicaceae, Wingman4l7, ClueBot NG, This lousy T-shirt, DanTrent, Widr, Calf85, Plantdrew, ProtossPylon and Anonymous: 29
Images File:L_loa_whole_HBa.jpg Source: https://upload.wikimedia.org/wikipedia/commons/5/5d/L_loa_whole_HBa.jpg License: Public domain Contributors: http://www.dpd.cdc.gov/dpdx/HTML/ImageLibrary/Filariasis_il.htm Original artist: CDC - DPDx
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