Tropical ataxic neuropathy, which is prevalent in the tropics causes significant disability as well as increased mortality and remains an enigmatic disease with no effective treatment or cure, even a century after its identification.

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It was first described in 1897 in Jamaica, and leads to numbness in the limbs, clumsy gait, confusion etc. As the name implies, it seems to be restricted to tropical countries.

It appears to affect adolescents and older individuals more than the rest of the population. There is currently no effective treatment.

The causes of TAN are unknown - though malnutrition and poor diet are considered as contributing factors. Additionally, the prevalence of the disease worldwide has not been accurately assessed, with estimates ranging from 0.6% to 24% of the population in some regions.

See: Tropical ataxic neuropathy – A century old enigma Neurology India, Vol 64, issue 6