[1] TAN has only been described as developing in Africa, South-east Asia, and the Caribbean (if Guiana be included).
[1] It has been estimated that 5% of surviving World War II prisoners of war held in the Far East acquired TAN; while they were held for 3.5 years or less, the TAN symptoms persisted chronically after they returned to temperate climates.
One affects adolescents, appears with retrobulbar optic neuropathy and evidence of malnutrition, and improves with better nutrition.
Paresthesias include sensations of numbness, heat, cold, tightness, crawling motion, tingling, pins and needles, and a feeling of walking on cotton or pebbles.
Affected people also suffer optic atrophy and sensory neural deafness, on both sides of the body.
Symptoms tend to worsen during the rainy season (see monsoon, harmattan), and are often worse at night.
[7] The behaviour and neurology of malnourished and cassava-fed rats has been compared to that of humans with TAN.