Cassava-induced spastic paralysis (Konzo) prevalent in the Congo

April 4, 2010, 6:39 pm

ProMED reports that cases of the chronic neurological  disease konzo — spastic paralysis caused by cyanide toxicity from eating improperly prepared cassava root — have become epidemic this year in the Democratic Republic of Congo.

Cassava is a vitally important crop worldwide, serving as a major source of calories for 200-300 million people.  It produces more carbohydrate per acre than any other plant.  One of the reasons it is so prolific is that the plant comes with its own insecticide. The glycoside linamarin releases cyanide when it comes into contact with the enzyme linamarase, which is also found in the root.  This reaction occurs when the plant is bruised or eaten raw.  The elaborate, lengthy preparation of cassava for human consumption involves grating the root and soaking it in warm water for several days — a procedure that releases and dissipates cyanide before the plant is consumed.

According to the textbook Experimental and Clinical Neurotoxicology:

“Konzo is characterized by an abrupt onset of symmetrical permanent paraparesis within minutes to a few hours.  . . . Initial symptoms are heaviness or trembling of the legs and difficulty walking.  The most severely affected are unable to stand immediately at onset.  Severity of the impairment varies, and the legs are always affect first and to a great extent than the arms.  Deficits range from mild hyperreflexia in the legs to severe spastic paraparesis with associated weakness of the trunk and arms.”

The discussion in ProMED notes that genetically-altered cyanogen-free cassava plants have been developed.

To read my column “Is Cassava Deadly?” in Emergency Medicine News, click here.

Thanks (again) to Chris Nickson from Life in the Fast Lane for sending me the link to the ProMED post.

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