Konzo
Encyclopedia
Konzo is an epidemic paralytic disease
first described by G. Trolli in 1938, 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.
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 glucoside
s 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.
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
, aptly describes the typical hypertonic gait of those afflicted.
It has been suggested that the disease may be prevented by advising population at risk to grow non-toxic ("sweet") cultivar
s 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. It remains to show if this can be used in practice in the desperate poverty where the disease occurs.
Paralysis
Paralysis is loss of muscle function for one or more muscles. Paralysis can be accompanied by a loss of feeling in the affected area if there is sensory damage as well as motor. A study conducted by the Christopher & Dana Reeve Foundation, suggests that about 1 in 50 people have been diagnosed...
first described by G. Trolli in 1938, who discovered it amongst the Kwango of the Belgian Congo
Belgian Congo
The Belgian Congo was the formal title of present-day Democratic Republic of the Congo between King Leopold II's formal relinquishment of his personal control over the state to Belgium on 15 November 1908, and Congolese independence on 30 June 1960.-Congo Free State, 1884–1908:Until the latter...
(now the Democratic Republic of Congo). The outbreaks are associated with several weeks of almost exclusive consumption of insufficiently processed "bitter" (cyanide
Cyanide
A cyanide is a chemical compound that contains the cyano group, -C≡N, which consists of a carbon atom triple-bonded to a nitrogen atom. Cyanides most commonly refer to salts of the anion CN−. Most cyanides are highly toxic....
-rich) cassava
Cassava
Cassava , also called yuca or manioc, a woody shrub of the Euphorbiaceae native to South America, is extensively cultivated as an annual crop in tropical and subtropical regions for its edible starchy tuberous root, a major source of carbohydrates...
as a famine food
Famine food
A famine food or poverty food is any inexpensive or readily-available foodstuff used to nourish people in times of extreme poverty or starvation, as during a war or famine...
. In northern Mozambique
Mozambique
Mozambique, officially the Republic of Mozambique , is a country in southeastern Africa bordered by the Indian Ocean to the east, Tanzania to the north, Malawi and Zambia to the northwest, Zimbabwe to the west and Swaziland and South Africa to the southwest...
the disease is known as mantakassa.
Symptoms
Outbreaks have mainly been reported among women and children in remote rural populations in EastEast Africa
East Africa or Eastern Africa is the easterly region of the African continent, variably defined by geography or geopolitics. In the UN scheme of geographic regions, 19 territories constitute Eastern Africa:...
and Central Africa
Central Africa
Central Africa is a core region of the African continent which includes Burundi, the Central African Republic, Chad, the Democratic Republic of the Congo, and Rwanda....
. 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
Cyanide poisoning
Cyanide poisoning occurs when a living organism is exposed to a compound that produces cyanide ions when dissolved in water. Common poisonous cyanide compounds include hydrogen cyanide gas and the crystalline solids potassium cyanide and sodium cyanide...
liberated from the naturally occurring glucoside
Glucoside
A glucoside is a glycoside that is derived from glucose. Glucosides are common in plants, but rare in animals. Glucose is produced when a glucoside is hydrolysed by purely chemical means, or decomposed by fermentation or enzymes....
s 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
Yaka
The Yaka are an ethnic group of Southwestern Democratic Republic of the Congo and Angola. They number about 300,000. They live in the forest and savanna areas between the Kwango and Wamba rivers. They are very artistic. Many of their religious and cultural customs transcend ethnic boundaries, and...
language and was the designation by the first affected population in Congo. The name, taken up by Hans Rosling
Hans Rosling
Hans Rosling is a Swedish medical doctor, academic, statistician and public speaker. He is Professor of International Health at Karolinska Institute and co-founder and chairman of the Gapminder Foundation, which developed the Trendalyzer software system.-Study and career:From 1967 to 1974 Rosling...
, 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") cultivar
Cultivar
A cultivar'Cultivar has two meanings as explained under Formal definition. When used in reference to a taxon, the word does not apply to an individual plant but to all those plants sharing the unique characteristics that define the cultivar. is a plant or group of plants selected for desirable...
s 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. It remains to show if this can be used in practice in the desperate poverty where the disease occurs.