Outbreak of an Unexplained Illness and the Possible Role of Nutrition: Nodding Syndrome in Kitgum District, Uganda

Nodding Syndrome (NS), an unexplained illness characterized by spells of head bobbing, particularly in the presence of food, has been reported in Sudan and Tanzania as early as 1962. Hypothesized causes include sorghum consumption, measles and onchocerciasis infection. In 2009, approximately 2000 possible cases were reported among internally displaced people in Uganda. We investigated the etiology of the outbreak. In December 2009, we conducted a multifaceted investigation. A case‐control study (n=49 case/village control pairs) assessed risk factors and collected biological specimens. A case was a previously developmentally normal 5‐ to 15‐year‐old with nodding plus another neurological deficit. Conditional logistic regression that adjusted for age was used to evaluate associations. There was no association between NS and sorghum consumption or previous measles. Exposure to munitions [aOR=9.9 (1.0, 96)], consumption of crushed roots [aOR=5.4 (1.3, 22)], and onchocerciasis [aOR=10.6 (1.3, 87.7)] was more likely in cases. Vitamin B6 deficiency was present in the majority of cases (84%) and controls (75%), and deficiencies of retinol, selenium, and zinc were also identified. Results raise new nutrition and toxic exposures as possible etiologies. Case‐series studies, further laboratory testing and follow‐up studies are underway. Funded by CDC DGDDER