Health factors associated with persistent konzo in four villages in the Democratic Republic of Congo (DRC)

Persistent konzo is low level incidence of konzo that is not associated with konzo epidemics due to drought or war. It has been reported from Mozambique and Tanzania. Various health factors associated with persistent konzo in four villages in Kasanji Health Area, Bandundu Province, DRC were studied, where there were 38 konzo cases in a population of 2283, with mean percentage konzo prevalence of 1.7%. Konzo occurred over the years since 1951 with 0 to 3 cases per year. Anthropometric measurements of children aged 0.5 to 14 y showed that 47% were stunted, 24% underweight, 16% had chronic energy deficiency and 16 to 24% suffered malnutrition. There was no significant difference between children from konzo households or from non-konzo households. The % konzo prevalence (%K) calculated from the equation %K = 0.06 %T + 0.035 %M, where %T = percentage of school children with urinary thiocyanate levels >350 µmol/L and %M = percentage of malnutrition, gave %K = 1.6 from non-konzo households and %K = 2.2 from konzo households, which agrees with the actual mean value of 1.7. However, the equation does not apply when either %T or %M is zero or for very high values of %K > 9.5. The value of %K is nearly twice as sensitive to changes in %T as to changes in %M, which partly explains the greater ease of prevention of konzo by reducing %T to zero, using the wetting method to remove cyanogens from cassava flour, than by reducing %M by broad based methods.