Konzo: an epidemic paralytic disease associated with subacute poisoning by cyanide in central Africa

Konzo disease (known as“mantakassa”in northern Mozambique) is an epidemic paralytic disease associated with subacute poisoning by cyanide found in insufficiently processed cassava. The name “Konzo” means "bound legs" in the Yaka language and correctly describes the typical hypertonic gait of those affected.

Paralysis develops suddenly and is symmetrical but does not progress.
The disease is associated with high dietary exposure to cyanide released from glycosides that normally are eliminated before cassava is eaten.
The full etiology and characteristics of neurological damage remain unclear.

Familial clustering is observed. Epidemics typically occur in the dry season in families living in poverty conditions and who have survived for weeks or months on bitter cassava. It is remarkable that not one single case of similar type of upper motor neuron damage has been reported from cyanide exposure without simultaneous protein malnutrition.

Some epidemiological studies have implicated the combination of high cyanide intake and simultaneous low intake of sulfur amino acids needed to detoxify cyanide as the main etiological factor.

A study was conducted to determine the epidemiological characteristics of konzo in health region No. 2 in the Central African Republic.

A descriptive cross-sectional study was conducted among patients enrolled during a one-month period (July 16 to August 16, 2007) of active surveillance for acute flaccid paralysis.
Eighty-one cases of konzo were identified during the studied period, representing a prevalence of 10 per 100,000. Mean age of the patients was 10.7+/-7.7 years. Children and women were the most affected. The main warning signs were fatigability (97.6 %), tremor (88.9 %), walking difficulty  (100.0 %), dysarthria (67.9 %) and a loss of visual acuity (65.4 %). The predominant neurological signs were lower limb paresis (90.0 %) and hyperesthesia (66.7 %).

Konzo is a serious public health problem in this region of the Central African Republic. Prevention of konzo depends on prompt restoration of food safety that enables higher protein intake and normal cassava processing practices
A programme of prevention needs to be set-up.