Chronic Cyanide Poisoning from Improperly Processed Cassava, July to August 2024: An Investigation of a Konzo Outbreak in Luampa District, Zambia

Introduction: Konzo is a neurological disorder that causes permanent spastic paralysis. It occurs mainly in rural areas and results from chronic cyanide intoxication due to consumption of inadequately processed bitter cassava. In July 2024, Luampa district reported eight cases of spastic paralysis diagnosed as Konzo. We investigated to identify the clinical, demographic, temporal, and environmental characteristics of this suspected outbreak. Methods: We conducted a field investigation in Luampa District from August 14–19, 2024. A case was defined as sudden onset of lower limb spastic paralysis with a history of regular cassava consumption; confirmation required elevated thiocyanate levels in blood or urine. Data were collected through structured interviews and medical record reviews. Environmental assessments included sampling of blood, urine, water, and food for cyanide analysis. Descriptive statistics summarized demographic data, and qualitative analysis identified common practices. Results: Eight cases of spastic paralysis were identified, with a median age of 7 years (IQR: 6.5–9.5), and 75% were male. All cases reported consuming bitter cassava as a staple food. Symptom onset occurred between 10 and 16 July 2024, with a median onset date of 11 July. Six cases (75%) were reported from Nakayembe Health Facility, and four of these originated from Sikuka village. Laboratory analysis detected cyanide in the blood and urine samples of all affected individuals, as well as in processed cassava samples collected from their households. Cyanide concentrations were not quantified. Environmental assessments documented cassava processing practices such as soaking unpeeled cassava in shallow wells and a lack of basic sanitary facilities. Conclusion: The findings are consistent with Konzo, likely resulting from chronic cyanide intoxication due to the consumption of inadequately processed bitter cassava. Immediate public health interventions are essential to prevent additional cases. These should include community education on safe cassava processing methods, such as peeling cassava before soaking and using running water or regularly flushed wells, and the promotion of low-cyanide cassava varieties. Strengthening these preventive measures will help protect affected communities from future outbreaks