Konzo

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For the Ethiopian ethnic group, see Konso people. For the Ugandan and DR Congo ethnic group, see Konjo people.
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Konzo [1] is an epidemic paralytic disease first described by G. Trolli in 1938,[2] who discovered it in the Kwango area of the Belgian Congo (currently the Democratic Republic of Congo). The outbreaks are associated with several weeks of almost exclusive consumption of insufficiently processed "bitter" (cyanide-rich) cassava as a famine food. In northern Mozambique the disease is known as mantakassa. [3] [4]


Contents

Symptoms [edit]

Outbreaks have mainly been reported among women and children in remote rural populations in East and Central Africa, such as DR Congo, [5] Mozambique, Tanzania and Central African Republic. [6] The onset of paralysis (spastic paraparesis) is sudden and symmetrical, affecting the legs more than the arms and the resulting disability is permanent, but does not progress.[7] [8] The disease onset is associated to high dietary exposure from cyanide liberated from the naturally occurring glucosides, such as linamarin and lotaustralin that normally are removed by processing before consumption of bitter cassava roots. However, during food shortage, war and other severe disruptions of life in poor rural cassava growing communities, the population is forced to make short-cuts in normal processing.

Diagnosis [edit]

The full etiology and the character of the neurodamage remains unclear. A number of epidemiological studies implicates the combination of high cyanide intake and simultaneous low intake of sulfur amino acids needed to detoxify cyanide as the main etiological factor. Familial clustering is observed. Epidemics typically occur in the dry season in households living in absolute poverty that have sustained themselves for weeks or months on bitter cassava.

It is noteworthy that not one single case of similar type of upper motor neuron damage has been reported from cyanide exposure without simultaneous protein malnutrition and even more that no case of konzo has yet been reported from poor cassava eating populations in South America.

"Konzo" means "bound legs" in the Yaka language in Southwestern DR Congo and was the designation by the first affected population in DR Congo as reported by Dr G. Trolli in 1938. The name, taken up by Hans Rosling[9] and colleagues aptly describes the typical spastic gait of those afflicted.

Recently, neuropsychological effects of konzo have been described from DR Congo. [10]

Prognosis [edit]

Although no treatment has been found it has been shown that affected individuals benefit considerably from rehabilitation and use of adequate walking aids. High awareness of the non-infectious character of the disease is needed to avoid actions that may aggravate the dietary situation of the poor populations that are affected by this disorder.

It has been suggested that the disease may be prevented by advising population at risk to grow non-toxic ("sweet") cultivars of cassava. However, their reason for preferential use of toxic ("bitter") cassava varieties is that the toxin and the bitterness associated to the toxin protect the crop from attacks by wild animals and thieves. Prevention of konzo depends on swift restoration of food security that enables higher protein intake and normal cassava processing practices.

Dr Howard Bradbury, an Australian plant chemist from the School of Botany and Zoology at the Australian National University in Canberra, has suggested the use of a simple new method of removing cyanide from flour made from cassava that will help.[11] It remains to show if this can be used in practice in the desperate poverty where the disease occurs.

References [edit]

  1. ^ WHO (1996). "Konzo– a distinct type of upper motoneuron disease". Weekly Epidemiological Record (in English, French) (Geneva) 71: 225–232. 
  2. ^ Trolli, G (1938). Résumé des observations réunies, au Kwango, au sujet de deux affections d'origine indeterminee: Paraplégie spastique épidémique, 'Konzo'des indigènes du Kwango (in French). Fonds Reine Elisabeth, Brussels. 
  3. ^ "Mantakassa: an epidemic of spastic paraparesis associated with chronic cyanide intoxication in a cassava staple area of Mozambique. 1. Epidemiology and clinical and laboratory findings in patients.". Bulletin of the World Health Organization 62 (3). 1984. pp. 477–84. 
  4. ^ "Mantakassa: an epidemic of spastic paraparesis associated with chronic cyanide intoxication in a cassava staple area of Mozambique. 2. Nutritional factors and hydrocyanic acid content of cassava products.". Bulletin of the World Health Organization 62 (3). 1984. pp. 485–92. 
  5. ^ Tylleskär T, Banea M, Bikangi N, Cooke RD, Poulter NH, Rosling H. (1992). "Cassava cyanogens and konzo, an upper motoneuron disease found in Africa". the Lancet 339 (8787): 208–11. 
  6. ^ Tylleskär T, Légué FD, Peterson S, Kpizingui E, Stecker P. (1994). "Konzo in the Central African Republic". Neurology 44 (5): 959–961. 
  7. ^ Tylleskär T, et al. (1997). "Konzo - the walk of the camelion, 8 minutes film". 
  8. ^ Howlett WP, Brubaker GR, Mlingi N, Rosling H. (1990). "Konzo, an epidemic upper motor neuron disease studied in Tanzania". Brain 113 (1): 223–235. 
  9. ^ "Hans Rosling Profile on TED.com". 
  10. ^ Boivin MJ, Okitundu D, Bumoko GMM, Sombo MT, Mumba D, Tylleskar T, Page CF, Tamfum Muyembe JJ, Tshala-Katumbay D. (2013). "Neuropsychological effects of konzo: a neuromotor disease associated with poorly processed cassava". Pediatrics 131: e1231–e1239. 
  11. ^ "New wetting method to remove cyanide from flour and help eliminate konzo". Cassava Cyanide Diseases Network. 2006. Retrieved 2007-12-31. 
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