Ian C. Denton

Control of konzo in DRC using the wetting method on cassava flour.

Fifty konzo cases were identified in four villages in Popokabaka Health Zone, DRC. One third of people had only one meal per day, mainly of cassava flour consumed as a thick porridge (fufu) and pounded, boiled cassava leaves. Retention of cyanogens in flour resulted from short soaking of cassava roots. A 1.5 years intervention was made in the largest village Kay Kalenge, where the wetting method was taught to all women of the village, who accepted it willingly. The total cyanide content of cassava flour was reduced to below 10 ppm. Fufu from treated flour tasted and stored better than fufu from untreated flour. The mean urinary thiocyanate content of 100 school children reduced from 332 to 130 μmole/L and the number of samples exceeding 350 μmole/L decreased from 26 to 0 during the intervention. No new konzo cases occurred, which included two dry seasons when konzo peaks. Konzo was first identified by Dr. Trolli in 1938 in Popokabaka Health Zone and it has now been prevented for the first time in the same area. The methodology is now in use in Boko Health Zone and we believe it is the most effective way to control konzo in tropical Africa.

Control of konzo by detoxification of cassava flour in three villages in the Democratic Republic of Congo

Three villages in Boko Health Zone, Bandundu Province, Democratic Republic of Congo (DRC), had 61 konzo cases and konzo prevalences of 2.5%, 4.1% and 7.5% respectively. Konzo cases occurred every year for 10 years and every month, peaking in July. The high mean cyanide content of cassava flour of 50 ppm was due to short soaking of cassava roots for 1-2 days instead of 3-4 days. Konzo cases were examined and village women taught the wetting method that removes cyanogens from flour. The villages were visited every month for 1 year following previous methodology. No new konzo cases occurred during the intervention, mean flour cyanide levels reduced from 50 to 14 ppm and mean urinary thiocyanate levels of school children reduced from 930 to 150 μmole/L. The percentage of children with urinary thiocyanate levels of >350 μmole/L was reduced from a maximum of 80 in Ikialala before the intervention to 0 in Ikusama, Ikialala and 3 in Imboso Mwanga 1 year later. This is the second time that konzo has been controlled and success depends on regular use of the wetting method by village women. The methodology is now being used in other villages in DRC with financial support of AusAID.

Mild method for removal of cyanogens from cassava leaves with retention of vitamins and protein

A mild method was developed to remove cyanogens from cassava leaves that involved three consecutive steps (1) pounding, (2) standing for 2h in the sun or 5h in the shade in the tropics and (3) washing three times in water. Four cassava cultivars were used and the mean residual total cyanide content after steps 1, 2 and 3 was 28%, 12% and 1%, respectively. The pounded cassava leaves retained their bright green colour and texture. The traditional method for removing cyanogens from pounded cassava leaves is by boiling in water which removed all cyanogens in 10 min. However this method caused the pounded leaves to become dull green in colour and would cause considerable losses of vitamins, protein and methionine, which are already in short supply in the diet of poor village people in tropical Africa.

Konzo prevention in six villages in the DRC and the dependence of konzo prevalence on cyanide intake and malnutrition

Highlights • In 6 villages we measured konzo prevalence, urinary thiocyanate and FC scores.• % konzo prevalence (%K), % high urine thiocyanate (%T), % malnutrition (%M) relate.• The results fitted an equation %K = 0.06%T + 0.035%M.• The wetting method was used by women over a 9-month intervention to prevent konzo.• The methodology has now been used with nearly 10,000 people in 13 villages.

Prevention of konzo in the Democratic Republic of Congo (DRC) using the wetting method and correlation between konzo incidence and percentage of children with high urinary thiocyanate level

There were 68 konzo cases in three villages in Boko Health Zone, Bandundu Province, Democratic Republic of Congo (DRC), where yearly incidence had increased greatly since 2009. The nine months long intervention to prevent konzo started in the wet season. Village women were taught the wetting method, after which there were no new konzo cases and urinary thiocyanate levels were low. Using data from four different interventions in March 2010, July 2011, September 2013 and the present intervention in October-November 2012, a correlation was found between the monthly cyanide intake (measured by percentage of children with high urinary thiocyanate level) and the monthly konzo incidence. This dose response relationship between cyanide intake and konzo incidence, together with the prevention of konzo in many villages using the wetting method to reduce cyanogen intake, shows that konzo is very likely to be due to high cyanide/low sulfur amino acid intake in a diet of bitter cassava.

Use of the wetting method on cassava flour in three konzo villages in Mozambique reduces cyanide intake and may prevent konzo in future droughts

Abstract Konzo is an irreversible paralysis of the legs that occurs mainly in children and young women associated with large cyanide intake from bitter cassava coupled with malnutrition. In East Africa outbreaks occur during drought, when cassava plants produce much more cyanogens than normal. A wetting method that removes cyanogens from cassava flour was taught to the women of three konzo villages in Mozambique, to prevent sporadic konzo and konzo outbreaks in the next drought. The intervention was in three villages with 72 konzo cases and mean konzo prevalence of 1.2%. The percentage of children with high (>350 μmol/L) urinary thiocyanate content and at risk of contracting konzo in Cava, Acordos de Lusaka, and Mujocojo reduced from 52, 10, and 6 at baseline to 17, 0, and 4 at conclusion of the intervention. Cassava flour showed large reductions in total cyanide over the intervention. The percentage of households using the wetting method was 30–40% in Acordos de Lusaka and Mujocojo and less in Cava. If the wetting method is used extensively by households during drought it should prevent konzo outbreaks and chronic cyanide intoxication. We recommend that the wetting method be taught in all konzo areas in East Africa.