A mysterious disease continues to grow in three African countries, including recently independent South Sudan. Nodding syndrome, named for the uncontrollable nodding that occurs, impairs physical growth, cognitive development and ultimately leads to premature death The characteristic nodding arises from seizures that cause lapses in neck muscle tone, letting the head fall forward. Seizures appear to be triggered by the act of chewing; thus, children have difficulty eating and eventually suffer from malnutrition and stunted growth. The disease is progressive and fatal, usually first appearing between ages 5 and 15.
Though first documented in 1962, the cause of nodding syndrome remains elusive. Experts have theorized environmental causes (such as toxic residue from ammunition in war zones), genetic factors, or dietary customs are to blame. Other possibilities include Onchocerca volvulus, the parasite responsible for river blindness, or a vitamin deficiency. The disease also exists in parts of Uganda and Tanzania but no linking factors have yet been found between the countries, meaning experts are still unsure of the true cause of nodding syndrome.