Revisiting Konzo Risk Factors in Three Areas Differently Affected by Spastic Paraparesis in Eastern Democratic Republic of the Congo Discloses a Prominent Role of the Nutritional Status-A Comparative Cross-Sectional Study.

This comparative cross-sectional study aimed to better understand the respective contributions of protein malnutrition and cassava-derived cyanide poisoning in the development of konzo. We compared data on nutritional status and cyanide exposure of school-age adolescent konzo-diseased patients to those of non-konzo subjects of similar age from three areas in the Eastern Democratic Republic of the Congo. Our results show that konzo patients had a high prevalence of both wasting (54.5%) and stunting (72.7%), as well as of cyanide poisoning (81.8%). Controls from Burhinyi and those from Idjwi showed a similar profile with a low prevalence of wasting (3.3% and 6.5%, respectively) and intermediate prevalence of stunting (26.7% and 23.9%, respectively). They both had a high prevalence of cyanide poisoning (50.0% and 63.0%, respectively), similar to konzo-patients. On the other hand, controls from Bukavu showed the lowest prevalence of both risk factors, namely chronic malnutrition (12.1%) and cyanide poisoning (27.6%). In conclusion, cassava-derived cyanide poisoning does not necessarily coexist with konzo outbreaks. The only factor differentiating konzo patients from healthy individuals exposed to cyanide poisoning appeared to be their worse nutritional status. This further suggests that, besides the known role of cyanide poisoning in the pathogenesis of konzo, malnutrition may be a key factor for the disease occurrence.

Konzo risk factors, determinants and etiopathogenesis: What is new? A systematic review.

Konzo is a toxico-nutritional upper motor neuron disease causing a spastic paraparesis in schoolchildren and childbearing women in some African countries. Almost a century since the first description of konzo, its underlying etiopathogenic mechanisms and causative agent remain unknown. This paper aims at refreshing the current knowledge of konzo determinants and pathogenesis in order to enlighten potential new research and management perspectives. Literature research was performed in PubMed and Web of Science databases according to the PRISMA methodology. Available data show that cassava-derived cyanide poisoning and protein malnutrition constitute two well-documented risk factors of konzo. However, observational studies have failed to demonstrate the causal relationship between konzo and cyanide poisoning. Thiocyanate, the current marker of choice of cyanide exposure, may underestimate the actual level of cyanide poisoning in konzo patients as a larger amount of cyanide is detoxified via other unusual pathways in the context of protein malnutrition characterizing these patients. Furthermore, the appearance of konzo may be the consequence of the interplay of several factors including cyanide metabolites, nutritional deficiencies, psycho-emotional and geo-environmental factors, resulting in pathophysiologic phenomena such as excitotoxicity or oxidative stress, responsible for neuronal damage that takes place at sparse cellular and/or subcellular levels.