Loa loa filaria: Difference between revisions

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style="background:#Template:Taxobox colour;"\|Template:Taxobox name
style="background:#Template:Taxobox colour;" \| Scientific classification
Kingdom:	Animalia;
Phylum:	Nematoda;
Class:	Chromadorea;
Order:	Spirurida;
Superfamily:	Filarioidea;
Family:	Onchocercidae;
Genus:	Loa;
Species:	L. loa;
Binomial name
	Loa loa; (Cobbold, 1864)
Synonyms
	Filaria loa Cobbold, 1864

VisualWikitext

Latest revision as of 21:17, 30 July 2015

This page is about microbiologic aspects of the organism(s). For clinical aspects of the disease, see Filariasis.

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Overview

Loa loa is the filarial nematode (roundworm) species that causes Loa loa filariasis. Its geographic distribution includes Africa and India.^[1] L. loa is one of three parasitic filarial nematodes that cause subcutaneous filariasis in humans. The two other filarial nematodes are Mansonella streptocerca and Onchocerca volvulus (causes river blindness). Maturing larvae and adults of the eye worm occupy the subcutaneous layer of the skin ; the fat layer; of humans, causing disease. The young larvae 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.

Pathophysiology

Morphology

Loa loa worms have a simple body including a head, body, and tail. Males range from 20mm to 34mm long and 350μm to 430μm wide. Females range from 20mm to 70mm long and are about 425μm wide.^[1]

Life Cycle

The vector for Loa loa filariasis are flies from two species of the genus Chrysops, C. silacea and C. dimidiata. During a blood meal, an infected fly (genus Chrysops, day-biting flies) introduces third-stage filarial larvae onto the skin of the human host, where they penetrate into the bite wound (1). The larvae develop into adults that commonly reside in subcutaneous tissue (2). The female worms measure 40 to 70 mm in length and 0.5 mm in diameter, while the males measure 30 to 34 mm in length and 0.35 to 0.43 mm in diameter. Adults produce microfilariae measuring 250 to 300 μm by 6 to 8 μm, which are sheathed and have diurnal periodicity. Microfilariae have been recovered from spinal fluids, urine, and sputum. During the day they are found in peripheral blood, but during the noncirculation phase, they are found in the lungs (3). The fly ingests microfilariae during a blood meal (4) . After ingestion, the microfilariae lose their sheaths and migrate from the fly's midgut through the hemocoel to the thoracic muscles of the arthropod(5). There the microfilariae develop into first-stage larvae (6) and subsequently into third-stage infective larvae (7). The third-stage infective larvae migrate to the fly's proboscis (8) and can infect another human when the fly takes a blood meal (1).

References

↑ ^1.0 ^1.1 Schmidt, Gerald et al. "Foundations of Parasitology". 7th ed. McGraw Hill, New York, NY, 2005.

Taxonomy Browser: Loa Loa. National Center for Biotechnology Information (NCBI).

Template:Helminthiases

[FoP-1] 1.0 ^1.1 Schmidt, Gerald et al. "Foundations of Parasitology". 7th ed. McGraw Hill, New York, NY, 2005.

[1]

@@ Line 1: / Line 1: @@
-__NOTOC__
 {{Taxobox
 | image_caption = ''Loa loa'' [[microfilaria]] in [[thin blood smear]]<br/>([[Giemsa stain]])
@@ Line 15: / Line 13: @@
 | synonyms = ''Filaria loa'' <small>Cobbold, 1864</small>
 }}
+__NOTOC__
+{{About0|Filariasis}}
+{{SI}}
 {{CMG}}
@@ Line 20: / Line 21: @@
 '''''Loa loa''''' is the [[filaria]]l [[nematode]] (roundworm) [[species]] that causes [[Loa loa filariasis]].  Its geographic distribution includes Africa and India.<ref name="FoP">Schmidt, Gerald et al.  "Foundations of Parasitology".  7th ed.  McGraw Hill, New York, NY, 2005.</ref>
 ''L. loa'' is one of three parasitic filarial nematodes that cause subcutaneous filariasis in humans.  The two other filarial nematodes are ''Mansonella streptocerca'' and ''Onchocerca volvulus'' (causes [[river blindness]]).
-Maturing [[larva]]e and adults of the eye worm occupy the [[subcutaneous]] layer of the [[skin]] ; the fat layer; of humans, causing disease. The young larvae develop in [[horseflies]] of the [[genus]] ''[[Chrysops]]'' (deer flies, yellow flies), including the species ''[[Chrysops dimidiata|C. dimidiata]]'' and ''C. silacea'', which infect humans by biting them.
+Maturing [[larva]]e and adults of the eye worm occupy the [[subcutaneous]] layer of the [[skin]] ; the fat layer; of humans, causing disease. The young larvae 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.
 ==Pathophysiology==
 ===Morphology===
-Loa loa worms have a simple body including a head, body, and tail.   Males range from 20mm to 34mm long and 350μm to 430μm wide.  Females range from 20mm to 70mm long and are about 425μm wide.<ref name="FoP"/>
+''Loa loa'' worms have a simple body including a head, body, and tail.   Males range from 20mm to 34mm long and 350μm to 430μm wide.  Females range from 20mm to 70mm long and are about 425μm wide.<ref name="FoP"/>
-===Life cycle===
+===Life Cycle===
-Three species involved in the life cycle include the parasite ''Loa loa'', the fly vector, and the human host:<ref>[http://www.dpd.cdc.gov/dpdx/HTML/Filariasis.htm "Filariasis".] Parasites and Health. Center for Disease Control.</ref>
+[[Image:L loa LifeCycle.gif|500 px|center]]
-* A vector fly bites an infected human host and ingests microfilariae.
+The vector for [[Loa loa filariasis]] are flies from two species of the genus Chrysops, C. silacea and C. dimidiata. During a [[blood]] meal, an infected fly (genus Chrysops, day-biting flies) introduces third-stage filarial larvae onto the skin of the human host, where they penetrate into the bite [[wound]] '''(1)'''. The larvae develop into adults that commonly reside in [[subcutaneous tissue]] '''(2)'''. The female worms measure 40 to 70 mm in length and 0.5 mm in diameter, while the males measure 30 to 34 mm in length and 0.35 to 0.43 mm in diameter. Adults produce microfilariae measuring 250 to 300 μm by 6 to 8 μm, which are sheathed and have diurnal periodicity. Microfilariae have been recovered from [[spinal fluid]]s, [[urine]], and [[sputum]]. During the day they are found in peripheral blood, but during the noncirculation phase, they are found in the [[lung]]s '''(3)'''. The fly ingests microfilariae during a blood meal '''(4)''' . After ingestion, the microfilariae lose their sheaths and migrate from the fly's [[midgut]] through the [[hemocoel]] to the thoracic muscles of the [[arthropod]]'''(5)'''. There the microfilariae develop into first-stage larvae '''(6)''' and subsequently into third-stage infective larvae '''(7)'''. The third-stage infective larvae migrate to the fly's proboscis '''(8)''' and can infect another human when the fly takes a blood meal '''(1)'''.
-* Microfilariae move to the fat body of the insect host.
-* Microfilariae develop into first stage larvae, then third stage larvae.
-* Third stage larvae (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.
-* Larvae mature into adults, who produce microfilariae that have been found in spinal fluid, urine, peripheral blood, and lungs.
 ==References==
@@ Line 44: / Line 35: @@
 {{Helminthiases}}
-[[ar:لوا لوائية]]
-[[cs:Vlasovec oční]]
-[[de:Loa loa]]
-[[es:Loa loa]]
-[[fr:Loa loa]]
-[[hu:Szemféreg]]
-[[pl:Loa loa]]
-[[pt:Loa loa]]
-[[sv:Loiasis]]
-[[Category:Parasites]]
-[[Category:Nematodes]]
-[[de:Loa loa]]
-[[fr:Loa loa]]