The character of the neurological injury is not clear. The disease onset is associated with high intake of cyanide from a diet of mostly bitter cassava, which is low in protein, particularly sulfur amino acids. These are essential for the detoxification in the body of cyanide to thiocyanate, which is removed in the urine.

• Cliff, J.; Martensson, J.; Lundquist, P.; Rosling, H.; Sorbo, B. (1985). “Association of high cyanide and low sulphur intake in cassava induced spastic paraparesis”. Lancet. 326 (8466): 1211–1213. doi:10.1016/s0140-6736(85)90742-1. PMID 2866292. S2CID 206001945.

A number of studies implicate the combination of high cyanide intake from bitter cassava and low intake of sulfur amino acids as the cause. It has now been shown that the month by month incidence of konzo is significantly correlated with the percentage of children with high urinary thiocyanate content, which is a measure of their cyanide intake. The importance of an adequate supply of protein sulfur amino acids is shown from three unrelated konzo epidemics in Mozambique, Tanzania and DRC. People of the same ethnic group living only 5 km away from those with konzo had near zero konzo prevalence, because in Mozambique they lived near the sea, in Tanzania they lived near Lake Victoria and had access to fish and in DRC they lived near the forest and had access to animal protein.^{[citation needed]}

• Ministry Of, Health (1984). “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): 477–84. PMC 2536324. PMID 6331909.
• Howlett, W. P.; Brubaker, G.; Mlingi, N.; Rosling, H. (1992). “A geographical cluster of konzo in Tanzania”. J Tropical Geographical Neurology. 2: 102–108.

The dose–response relationship between konzo incidence and cyanide intake, together with the prevention of konzo in many villages by reducing cyanide intake from cassava (see below) and the importance of sulfur amino acids in prevention of konzo, shows that konzo is very likely due to high cyanide/low sulfur amino acid intake in a diet of bitter cassava. Konzo does not occur unless these conditions are met, which occurs only in remote villages in six tropical African countries. The total number of reported cases up to 2009 was 6788, but most cases are never reported and there was an estimate of 100,000 cases in DRC alone in 2002.

• Nzwalo H, Cliff J. (2011). “Konzo: from poverty, cassava, and cyanogen intake to toxico-nutritional neurological disease”. PLoS Negl Trop Dis. 5 (6): e1051. doi:10.1371/journal.pntd.0001051. PMC 3125150. PMID 21738800.
• Diasolua Ngudi, D. (2005), Konzo and cassava toxicity: a study of associated nutritional factors in the Popokabaka District, DRC. Ph D Thesis, Universiteit Gent, Belgium.

Konzo is spreading geographically as cassava is being grown in new areas where there is little knowledge of processing methods to remove cyanogens.

• Nzwalo H, Cliff J. (2011). “Konzo: from poverty, cassava, and cyanogen intake to toxico-nutritional neurological disease”. PLoS Negl Trop Dis. 5 (6): e1051. doi:10.1371/journal.pntd.0001051. PMC 3125150. PMID 21738800.
• Nhassico, D.; Muquingue, H.; Cliff, J.; Cumbana, A.; Bradbury, J. H. (2008). “Rising African cassava production, diseases due to high cyanide intake and control measures” (PDF). Journal of the Science of Food and Agriculture. 88 (12): 2043–2049. doi:10.1002/jsfa.3337.

Konzo epidemics occur due to war which causes disruption of life in poor villages and drought, when the plant increases the cyanogen content of roots 2–4 times and the cyanide content of cassava flour also increases greatly. Konzo is also endemic in certain areas.^{[citation needed]}

• Bokanga, M.; Ekanayake, I.J.; Dixon, A.G.O.; Porto, M.C.M. (1994). “Genotype environment interactions for cyanogenic potential in cassava”. Acta Horticulturae (375): 131–139. doi:10.17660/actahortic.1994.375.11. hdl:10568/97377.
• Ernesto, M.; Cardoso, P.; Nicala, D.; Mirioe, E.; Massaza, F.; Cliff, J.; Haque, M.R.; Bradbury, J.H. (2002). “Persistent konzo and cyanogen toxicity from cassava in northern Mozambique” (PDF). Acta Tropica. 82 (3): 357–362. doi:10.1016/s0001-706x(02)00042-6. PMID 12039675.
• Cardoso, A.P.; Mirione, E.; Ernesto, M.; Massaza, F.; Cliff, J.; Haque, M.R.; Bradbury, J.H. (2005). “Processing of cassava roots to remove cyanogens” (PDF). Journal of Food Composition and Analysis. 18 (5): 451–460. doi:10.1016/j.jfca.2004.04.002.

Traditional methods of processing cassava to remove cyanogens consist of sun drying and heap fermentation in East Africa, which are inadequate in removal of cyanogens even in a year of normal rainfall. In Central Africa soaking (retting) of cassava roots in water for 4–5 days is adequate, but short soaking for 1–2 days leaves large amounts of cyanogens in flour and leads to konzo. In West Africa a roasted product called garri is produced by a different method than that used to produce flour, which reduces the total cyanide content to 10–20 ppm. There are no reported cases of konzo west of Cameroon.

• Cardoso, A.P.; Mirione, E.; Ernesto, M.; Massaza, F.; Cliff, J.; Haque, M.R.; Bradbury, J.H. (2005). “Processing of cassava roots to remove cyanogens” (PDF). Journal of Food Composition and Analysis. 18 (5): 451–460. doi:10.1016/j.jfca.2004.04.002.
• Banea, M.; Poulter, N.H.; Rosling, H. (1992). “Shortcuts in cassava processing and risk of dietary cyanide exposure in Zaire”. Food and Nutrition Bulletin. 14 (2): 137–143. doi:10.1177/156482659201400201

However another neurological disease called tropical ataxic neuropathy (TAN), occurs amongst older people in West Africa (including south-west Nigeria, and also Tanzania, Uganda, Kenya, West Indies and South India) and is probably due to long term intake of cyanogens from cassava at a lower level than that needed to cause konzo.

• Cardoso, A.P.; Mirione, E.; Ernesto, M.; Massaza, F.; Cliff, J.; Haque, M.R.; Bradbury, J.H. (2005). “Processing of cassava roots to remove cyanogens” (PDF). Journal of Food Composition and Analysis. 18 (5): 451–460. doi:10.1016/j.jfca.2004.04.002.

Prevention

Konzo can be prevented by use of the “wetting method,” which is used to remove residual cyanogens from cassava flour, as an additional processing method. Cassava flour is placed in a bowl and the level marked on the inside of the bowl. Water is added with mixing until the height of the wet flour comes up to the mark. The wet flour is placed in a thin layer on a mat for 2 hours in the sun or 5 hours in the shade to allow the escape of hydrogen cyanide produced by the breakdown of linamarin by the enzyme linamarase. The damp flour is then cooked in boiling water in the traditional way to produce a thick porridge called “fufu” or “ugali”, which is flavoured by some means such as a sauce. The wetting method is accepted by rural women because it requires little extra work or equipment and produces fufu which is not bitter, because the bitter tasting linamarin has gone.

• Bradbury, J.H. (2006). “Simple wetting method to reduce cyanogen content of cassava flour” (PDF). Journal of Food Composition and Analysis. 19 (4): 388–393. doi:10.1016/j.jfca.2005.04.012.
• Harford, Tim (September 4, 2019). “How do people learn to cook a poisonous plant safely?”. BBC News. Retrieved 4 September 2019.
• Cumbana, A.; Mirione, E.; Cliff, J.; Bradbury, J.H. (2007). “Reduction of cyanide content of cassava flour in Mozambique by the wetting method” (PDF). Food Chemistry. 101 (3): 894–897. doi:10.1016/j.foodchem.2006.02.062.
• Bradbury, J.H.; Denton, I.C. (2010). “Rapid wetting method to reduce cyanogen content of cassava flour” (PDF). Food Chemistry. 121 (2): 591–594. doi:10.1016/j.foodchem.2009.12.053.
• Banea, J.P.; Bradbury, J.H.; Mandombi, C.; Nahimana, D.; Denton, I.C.; Kuwa, N.; Tshala Katumbay, D. (2014). “Effectiveness of wetting method for control of konzo and reduction of cyanide poisoning by removal of cyanogens from cassava flour” (PDF). Food and Nutrition Bulletin. 35 (1): 28–32. doi:10.1177/156482651403500104. hdl:1885/66470. PMID 24791576. S2CID 21189051.

In 2010 the wetting method was taught to the women in Kay Kalenge village, Popokabaka Health Zone, Bandundu Province, DRC, where there were 34 konzo cases. The women used the method and during the intervention there were no new konzo cases and the urinary thiocyanate content of the school children fell to safe levels. Konzo had been prevented for the first time ever in the same health zone in which it had first been discovered by Dr Trolli in 1938. Fourteen months after the intervention ceased the village was visited again. It was found that there were no new cases of konzo, the school children had low urinary thiocyanate levels, the wetting method was still being used and it had spread by word of mouth to three nearby villages. It is important to teach the women that konzo is due to a poison present in their food, to get them to regularly use the wetting method and posters are available in 13 different languages as a teaching aid as an additional method to remove residual cyanogens.

• Banea, J.P.; Bradbury, J.H.; Mandombi, C.; Nahimana, D.; Denton, I.C.; Kuwa, N.; Tshala Katumbay, D. (2014). “Effectiveness of wetting method for control of konzo and reduction of cyanide poisoning by removal of cyanogens from cassava flour” (PDF). Food and Nutrition Bulletin. 35 (1): 28–32. doi:10.1177/156482651403500104. hdl:1885/66470. PMID 24791576. S2CID 21189051.
• Banea, J.P.; Nahimana, D.; Mandombi, C.; Bradbury, J.H.; Denton, I.C.; Kuwa, N. (2012). “Control of konzo in DRC using the wetting method on cassava flour” (PDF). Food and Chemical Toxicology. 50 (5): 1517–1523. doi:10.1016/j.fct.2012.02.001. PMID 22342647.

The wetting method has now been used in 13 villages in the DRC with a collective population of nearly 10,000 people. The time of the intervention has been reduced from 18 months in the first intervention, to 12 months in the second intervention, to 9 months in the third and fourth interventions. This has reduced the cost per person of the intervention to prevent konzo by removing cyanogens from cassava flour, to $16 per person. This targeted method to reduce cyanide intake is much cheaper and more effective in preventing konzo than broad based interventions.^{[citation needed]}

• Banea, J.P.; Nahimana, D.; Mandombi, C.; Bradbury, J.H.; Denton, I.C.; Kuwa, N. (2012). “Control of konzo in DRC using the wetting method on cassava flour” (PDF). Food and Chemical Toxicology. 50 (5): 1517–1523. doi:10.1016/j.fct.2012.02.001. PMID 22342647.
• Banea, J.P.; Bradbury, J.H.; Mandombi, C.; Nahimana, D.; Denton, I.C.; Kuwa, N.; Tshala Katumbay, D. (2013). “Control of konzo by detoxification of cassava flour in three villages in the Democratic Republic of Congo” (PDF). Food and Chemical Toxicology. 60: 506–513. doi:10.1016/j.fct.2013.08.012. PMID 23941775.