Clinical and epidemiologic characteristics of nodding syndrome in Mundri County, southern Sudan.

BACKGROUND Nodding syndrome (repetitive nodding and progressive generalized seizures) is assuming epidemic proportions in South Sudan, Tanzania and Uganda. OBJECTIVE To describe clinical and epidemiological features of nodding syndrome in southern Sudan based on preliminary investigations conducted in 2001 and 2002. METHOD Household surveys, clinical, electrophysiological (EEG) assessments, informant interviews and case-control studies were conducted in the town of Lui and the village of Amadi in southern Sudan. RESULTS Nodding syndrome is characterized by involuntary repetitive nodding of the head, progressing to generalized seizures; mental and physical deterioration. The EEGs were consistent with progressive epileptic encephalopathy. Prevalence of Nodding syndrome in Lui and Amadi was 2.3% and 6.7% respectively. All case control studies showed a positive association between cases and Onchocerca volvulus. A history of measles was negatively associated with being a case: 2/13 of cases and 11/19 of controls had had measles: odds ratio 0.13 (95% CI 0.02, 0.76). Environmental assessment did not reveal any naturally occurring or manmade neurotoxic factors to explain Nodding Syndrome, although fungal contamination of food could not be ruled out. CONCLUSION Nodding Syndrome was strongly associated with Onchocerca volvulus. There was no evidence to suggest an environmental pollutant, chemical agent, or other toxic factor.