Konzo

For the Ethiopian ethnic group, see Konso people. For the Ugandan and DR Congo ethnic group, see Konjo people.

Konzo is an epidemic paralytic disease first described by G. Trolli in 1938,^[1] who discovered it amongst the Kwango of the Belgian Congo (now 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.

Symptoms

Outbreaks have mainly been reported among women and children in remote rural populations in East and Central Africa. The onset of paralysis (hypertonic paraparesis) is sudden and symmetrical and the resulting disability is permanent, but does not progress. The disease onset is associated to high dietary exposure from cyanide liberated from the naturally occurring glucosides 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

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 and was the designation by the first affected population in Congo. The name, taken up by Hans Rosling,^[2] aptly describes the typical hypertonic gait of those afflicted.

Prognosis

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.^[3] It remains to show if this can be used in practice in the desperate poverty where the disease occurs.

References

1. ^ Trolli, G (1938) (in French). Paraplégie spastique épidémique, 'Konzo'des indigènes du Kwango. Brussels. http://scholar.google.com/scholar?hl=en&q=konzo+trolli&btnG=Search&lr=lang_fr&as_sdt=2000. 
2. ^ "Hans Rosling Profile on TED.com". http://www.ted.com/speakers/hans_rosling.html. 
3. ^ "New wetting method to remove cyanide from flour and help eliminate konzo". Cassava Cyanide Diseases Network. 2006. http://online.anu.edu.au/BoZo/CCDN/new_method.html. Retrieved 2007-12-31. 

• W. P. HOWLETT, G. R. BRUBAKER, N. MLINGI and H. ROSLING (1990). KONZO, AN EPIDEMIC UPPER MOTOR NEURON DISEASE STUDIED IN TANZANIA. 113. Brain, a journal of neurology. pp. 223–235. http://brain.oxfordjournals.org/cgi/content/abstract/113/1/223.