30 April 2012

Elephantiasis: Two Causes



            Many of us who have cared for patients in tropical settings are familiar with the grotesque, disfiguring and disabling swelling of the legs caused by elephantiasis.  Caused by a threadlike, parasitic filarial roundworm, Wucheria bancrofti, this disease affects over 40 million people worldwide in tropical settings.  The parasite is transmitted by mosquitos.  The adult worm blocks the lymphatics of the lower extremities, causing chronic swelling, then wartlike thickening of the skin, and considerable disability.  Scrotal swelling due to hydrocoele is common in males.  Treatment with Ivermectin and diethyl carbamizine kills the adult worms, but re-infection is common.
            Another lesser-known cause of elephantiasis is a condition called podoconiosis.  It occurs in subsistence farmers in areas of red volcanic soils.  Microsilica particles contained in these soils penetrate through bare feet, enter the lymphatics of the lower extremities, and cause chronic inflammation and blockage, producing the same pattern of chronic swelling and warty tumors found in filarial elephantiasis.  There is no effective treatment for podoconiosis.   Prevention, of course, is by wearing protective covering on the feet.  There are currently estimated to be 4 million cases in the world, mainly in Sub-Saharan Africa, with a scattering in Latin America.  Of interest is that this relatively common disabling condition was little known until recent years.  It is important for us to be aware of these two causes of elephantiasis and their differences in treatment and prevention.
Ref:  Molyneux, D.H.  Tropical Lymphedemas-Control and Prevention. NEJM 366:1169-72, 2012
Submitted by Roger Boe MD

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