Nodding Syndrome

Scott F. Dowell

, James J. Sejvar, Lul Riek, Katelijn A.H. Vandemaele, Margaret Lamunu, Annette C. Kuesel, Erich Schmutzhard, William Matuja, Sudhir Bunga, Jennifer Foltz, Thomas B. Nutman, Andrea S. Winkler, and Anthony K. Mbonye

Author affiliations: Centers for Disease Control and Prevention, Atlanta, Georgia, USA (S.F. Dowell, J.J. Sejvar, S. Bunga, J. Foltz); Ministry of Health, Juba, South Sudan (L. Riek); World Health Organization, Geneva, Switzerland (K.A.H. Vandemaele, M. Lamunu, A.C. Kuesel); University of Innsbruck, Innsbruck, Austria (E. Schmutzhard); Muhimbili University, Dar es Salaam, Tanzania (W. Matuja); National Institutes of Health, Bethesda, Maryland, USA (T.B. Nutman); Technical University of Munich, Munich, Germany (A.S. Winkler); Ministry of Health, Kampala, Uganda (A.K. Mbonye); Makerere University, Kampala (A.K. Mbonye)

Abstract

An epidemic illness characterized by head nodding associated with onchocerciasis has been described in eastern Africa since the early 1960s; we summarize published reports and recent studies. Onset of nodding occurs in previously healthy 5–15-year-old children and is often triggered by eating or cold temperatures and accompanied by cognitive impairment. Its incidence has increased in Uganda and South Sudan over the past 10 years. Four case–control studies identified modest and inconsistent associations. There were nonspecific lesions seen by magnetic resonance imaging, no cerebrospinal fluid inflammation, and markedly abnormal electroencephalography results. Nodding episodes are atonic seizures. Testing has failed to demonstrate associations with trypanosomiasis, cysticercosis, loiasis, lymphatic filariasis, cerebral malaria, measles, prion disease, or novel pathogens; or deficiencies of folate, cobalamin, pyridoxine, retinol, or zinc; or toxicity from mercury, copper, or homocysteine. There is a consistent enigmatic association with onchocerciasis detected by skin snip or serologic analysis. Nodding syndrome is an unexplained epidemic epilepsy.

Nodding syndrome as a distinctive entity was reported from southern Sudan in the 1990s and investigated by local authorities and the World Health Organization (WHO) during 2001–2002 (1,2). In retrospect, children with head nodding, or rhythmic dorsoventral movements of the head (3), as 1 characteristic feature of epilepsy syndromes, had been observed in Tanzania, Liberia, and western Uganda as far back as the 1960s but were not studied separately or described as a distinctive clinical group (3–5). The term nodding disease was first applied in southern Sudan in the 1990s to describe the occurrence of repetitive head nodding, characteristically occurring among children while eating, and variably associated with other seizure activity, neurologic and cognitive impairment, delayed puberty, and growth retardation.
Thousands of cases have been reported from southern Tanzania, northern Uganda, and South Sudan, although much smaller numbers have been documented and investigated in any detail (6–13). The effect of the disease on families and communities can be devastating because previously healthy young children drop out of school, lose the ability to eat, and require constant oversight because they might fall into a cooking fire or wander off and drown. Local authorities and national governments requested assistance from WHO, the US Centers for Disease Control and Prevention (CDC), and other agencies.