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From the field : Myiasis

Christophe is happy to report the birth of \”Amazonia\”, a two cm long worm that growed in his leg after an expedition through the Amazone.

Christophe: “During several days I had pain in my leg due to the worm. Extraction brought a lot of relief!”

Myiasis is the present of fly larvae in the body (cutaneous, oral, nasal, ocular, urogneital, gastrointestinal)

About 80% of the infections occur in Latin America (Bolivia, Peru and Brazil) and are due to the Dermatobia fly  (human bot fly).  This fly lays the eggs on a bloodsucking insect (mostly a mosquitoe). Then this vector insect infects a host and the larvae develop further in the body during 4 to 10 weeks. Afterwards the larvae drop to the ground and become new flies.

20 % of the infections occur in Africa and are caused by the Cordylobia fly (the tumbu or Putsi fly). This fly puts the eggs in sand or clothes left drying and the host becomes infected by direct or indirect skin contact. The larvae develop about 8 to 10 days in the host and then drop to the ground to become new flies

Cutaneous myiasis is characterized by one or more, mostly painfull, furuncular lesions. The lesions have a central pore that frequently release serous fluid. The diagnosis of cutaneous myiasis is clinical, the use of imaging techniques is not neccesary.  If, due to unclear complaints, imaging techniques are used, myiais in other parts of the body can sometimes be found. 

Treatment consist of manual extraction, which is successful in 75 % of the cases.  To make the extraction easier , the larvae can be coaxed by depriving it from oxygen by applying vaseline on the leasion. The larve will initiate to (partly) exit the cavity. Another trick is to inject lignocaine in the base of the cavity which will force the larve out by the build up of pressure in the cavity. If manual extraction is not successful the larva has to be removed surgical.

The use of antibiotics is a controversy, but always indicated when signs of a secondary infection are present. However, in practice , 75 % of the patients don’t get antibiotics . Although antibiotics are not administered, the occurence of a secundary infection is rare. Routine tetanus profylaxis is advised.

Christophe: \”I wondered more than 10 days why the wound didn’t heal.  At a second medical consultation a second worm was extracted out of the wound! It is apparantly not so uncommon that more than one worm is present in the same wound. I hope it will heal swiftly now!\”

 

Thanks to Christophe for the pictures.

Christophe Le Saux is a French ultrarunner and adventurer( who can be followed by his facebook page)

Ref:

– Journal of Travel Medicine 2015: vol12 ( nr 4): 232 – 236

– www.cdc.gov/parasites/myiasis/biology

– Medscape topic Myiasis