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A team of epidemiologists from the US Centers for Disease Control and Prevention (CDC) has returned from South Sudan still baffled by the disease it went to investigate.
Nodding syndrome appears to be growing in incidence, with more than 2,000 children affected in northern Uganda by late 2009 and thousands of children suffering from it in newly independent South Sudan. It is also known in a remote, mountainous region of Tanzania.
A member of the CDC team told Nature that, in one village it visited, almost every family had an affected child.
Most children who get it pick it up between five and 15 years of age. The nodding occurs when abnormal activity in the brain causes the neck muscles to relax. The disease is also characterised by small seizures that can be spotted only on brain scans; brain atrophy; malnutrition; stunted growth; and susceptibility to accidents — as well as social isolation because of fears that it is infectious.
Scientists cannot find any obvious cause of the disease, such as dietary or cultural changes, chemical exposures during wartime, or genetics (though there is evidence the latter may play a role).
There is evidence for and against the river blindness parasite (Onchocerca volvulus) playing a role, and researchers are also investigating lack of vitamin B6 as a possible cause.
Link to full article in Nature