Cassava food toxins, konzo disease, and neurodegeneration in sub-Sahara Africans.

Endemoepidemic neurodegenerative diseases putatively caused by food toxins have been reported around the globe with no clear understanding of their pathogenetic mechanisms. These diseases include the amyotrophic lateral sclerosis/parkinsonism dementia complex among the Guamanians; neurolathyrism among Europeans, Indians, and populations of the Horn of Africa; and tropical ataxic neuropathy or konzo among sub-Sahara Africans. We focus on the molecular determinants of susceptibility to konzo, a poorly known self-limited and irreversible upper motor neuron disease (spastic paraparesis) highly prevalent in Congo-Kinshasa, Mozambique, Tanzania, Central African Republic, Angola, and Cameroon. The main clinical picture consists of a symmetrical, permanent, and irreversible spastic paraparesis with no signs of sensory or genitourinary impairments. Severely affected individuals may present with a tetraparesis and pseudobulbar signs. The disease konzo was named after a fetish used by the “Yaka” population of Congo-Kinshasa. The World Health Organization has adopted the following epidemiologic criteria for the disease: 1) an abrupt onset (<1 week) of weakness in legs and a nonprogressive course of the disease in a formerly healthy person, 2) a symmetrical spastic abnormality when walking and/or running, and 3) bilaterally exaggerated knee and/or ankle jerks without signs of disease of the spine.