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

Six villages in Boko Health Zone, Bandundu Province, DRC, were studied with 4588 people, 144 konzo cases and konzo prevalences of 2.0-5.2%. Konzo incidence is increasing rapidly in this area. Food consumption scores were obtained from the households with konzo and the mean % malnutrition calculated for each village. Urine samples were obtained from 50 school children from each village and % high urinary thiocyanate content (>350 µmol/L) determined. The experimental data relating % konzo prevalence (%K) to % children with high urinary thiocyanate content (%T) and % malnutrition (%M) for the six villages were fitted to an equation %K = 0.06%T + 0.035%M. This confirms that konzo is due to a combination of high cyanide intake and malnutrition. The village women used the wetting method to remove cyanogens from cassava flour. During the 9-month intervention there were no new cases of konzo; cyanide in flour had reduced to WHO safe levels and mean urinary thiocyanate levels were greatly reduced. To prevent konzo at least 60-70% of women should use the wetting method regularly. The wetting method is now accepted by the World Bank, FAO and WHO as a sensitive intervention. Four successful konzo interventions have involved nearly 10,000 people in 13 villages, the cost is now $16 per person and the methodology is well established.

Effectiveness of wetting method for control of konzo and reduction of cyanide poisoning by removal of cyanogens from cassava flour.

BACKGROUND: Konzo is an irreversible paralysis of the legs that occurs mainly among children and young women in remote villages in tropical Africa and is associated with a monotonous diet of bitter cassava. Konzo was discovered in 1938 by Dr. G. Trolli in the Democratic Republic of Congo (DRC). It also occurs in Mozambique, Tanzania, Cameroon, Central African Republic, and Angola. It was first controlled in Kay Kalenge village, DRC, in 2011 with the use of a wetting method to remove cyanogens from cassava flour. Fourteen months later, another visit was made to Kay Kalenge. OBJECTIVE: To determine whether Kay Kalenge women were still using the wetting method, whether there were new cases of konzo, and whether the wetting method had spread to other villages. METHODS: Meetings were held with chiefs, leaders, and heads of mothers' groups, women from 30 households were interviewed, and three nearby villages were visited. Total cyanide and thiocyanate were analyzed in cassava flour and urine samples, respectively. RESULTS: The women in Kay Kalenge village still used the wetting method. There were no new cases of konzo. The mean cyanide content of the flour samples was 9 ppm, and no child had a mean urinary thiocyanate content greater than 350 micromol/L. The use of the wetting method had spread naturally to three adjacent villages. CONCLUSIONS: The wetting method has been readily accepted by rural women as a simple and useful method to control konzo by removing cyanide from cassava flour, and its use has spread to nearby villages. The wetting method should be promoted by health authorities to control konzo and reduce cyanide poisoning from high-cyanide cassava flour.

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.

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.

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.

Uptake of wetting method in Africa to reduce cyanide poisoning and konzo from cassava.

Cassava contains cyanogenic glucosides which are hydrolysed by an enzyme linamarase to produce cyanohydrins which breakdown to toxic cyanide. Cyanide ingestion from bitter cassava can cause cyanide poisoning sometimes leading to death and also konzo, an irreversible paralysis of the legs which occurs mainly in children and young women. In 2005 we developed a simple wetting method that reduces the total cyanide content of cassava flour 3-6-fold. It involves wetting the flour, spreading it in a thin layer in the shade for 5h and using it the same day to make traditional thick porridge (ugali). The method was readily accepted by rural women and requires no additional equipment or water. Laminated, illustrated posters describing the method are available for free in ten languages, see http://online.anu.edu.au/BoZo/CCDN/. An equally effective treatment method is to expose wet flour in a thin layer in the sun for 2h. Projects for rehabilitation and prevention of konzo occurred in Mozambique in 2007 and in 2008-2009 in Tanzania, funded by AusAID. The Ministry of Health in Mozambique is now using our posters in Macua. In Uvira DRC, the wetting method has been taught in many villages and over 1200 posters distributed.

Persistent konzo and cyanogen toxicity from cassava in northern Mozambique.

We aimed to detect new cases of konzo and monitor cyanogen exposure from cassava flour in communities previously affected by konzo epidemics in Nampula Province, northern Mozambique. Other objectives were to detect subclinical upper motor neuron damage in schoolchildren and test a new kit to measure urinary thiocyanate concentration. In 1999 and 2000, we carried out active and passive case detection for konzo in Memba and Mogincual Districts. In July and October, 1999, we collected cassava flour from 30 houses in three communities and measured cyanogen concentrations with a picrate kit. In October 1999, we examined all schoolchildren in three communities for ankle clonus and measured urinary thiocyanate concentration in thirty schoolchildren in each of five communities with a picrate kit. We found 27 new cases of konzo in Mogincual District. Mean total cyanogen concentrations in cassava flour varied between both seasons and years, but were always high, ranging from 26 to 186 ppm. Very high mean levels at three sites in November 1998 and July 1999 were probably due to low rainfall in the 1997-1998 season. The proportion of schoolchildren with ankle clonus varied from 8 to 17%. The new picrate kit for urinary thiocyanate worked well; mean concentrations in schoolchildren ranged from 225 to 384 micromol x l(-1). Konzo and sub-clinical upper motor neuron damage persist in poor rural communities in northern Mozambique, associated with high cyanogen concentrations in cassava flour and high urinary thiocyanate concentrations in schoolchildren.