Thursday, November 11, 2010

80 某君到非洲旅遊回來一段時間後因皮下潰瘍經診斷為感染麥地那蟲(Dracunculus medinensis),該君最可能是如何被感染的呢?
被斑虻(Chrysops)叮咬 被幼蟲鑽進而感染
喝到感染劍水蚤的水 吃到沒有煮熟的蛇肉

answer is 喝到感染劍水蚤的水
劍水蚤 copepods


the chryrops ( Deer fly or Mango fly ) is associated with : LOA LOA

Treatment
Treatment includes the extraction of the adult guinea worm by rolling it a few centimeters per day or preferably by multiple surgical incisions under local anaesthesia. No drug is effective in killing the worm. Protection of drinking water from being contaminated with Cyclops and larvae are effective preventive measures.

Dracunculus medinensis is a nematode that causes dracunculiasis.[1]

Dracunculiasis, also known as Guinea worm disease, is caused by the large female nematode, Dracunculus medinensis,[2] which is among the longest nematodes infecting humans.[3] The adult female is primarily larger than the adult male. The longest adult female recorded was 800 millimetres (31 in), while the adult male was only 40 mm (1.6 in).[4] Mature female worms migrate along subcutaneous tissues to reach the skin below the knee, forming a painful ulcerating blister.[3] They can also emerge from other parts of the body like the head, torso, upper extremities, buttocks, and genitalia.[4]


life cycle:

Humans become infected by drinking unfiltered water containing copepods (small crustaceans) that have been infected with D. medinensis larvae. After ingestion, the copepods die and release the larvae, which then penetrate the host's stomach, intestinal wall, and enter into the abdominal cavity and retroperitoneal space. After maturing, adult male worms die while the females migrate in the subcutaneous tissues towards the surface of the skin. After about a year of infection, the female worm forms a blister on the skin, generally on the distal lower extremity (foot), which breaks open. The patient then seeks to relieve the local discomfort by placing their foot in water, but when the lesion comes into contact with water, the female worm emerges and releases her larvae. The larvae are then ingested by a copepod, and after two weeks (and two molts) the larvae becomes infectious. Ingestion of the copepods is the last stage that completes the cycle


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