Two hundred Ugandan children, dead. Roughly 4,000 more harmed, many rendered incapable of living full lives as adults. All since 2009 — and with no end in sight.

If you think the killer here is Joseph Kony, you’re wrong. It’s a sinister illness called Nodding Disease, and the problem is getting worse.

Nodding Disease first appeared in Tanzania in 1962, but was limited to some secluded areas and did not spread much, if at all. At the time, the disease’s unique symptom — uncontrollable nodding — was more a curiosity than anything else, and given the generally poor health of people in the mountainous areas it struck, the disease was not necessarily thought to be anything distinct. But in around 2003, the nodding symptoms re-appeared in South Sudan and, by 2009, had spread to northern Uganda.

The disease strikes children, affecting those typically between the ages of five and fifteen. When children with Nodding Disease feels cold or, worse, eat, they have a seizure, causing some to enter into an uncontrolled, persistent nod. When the child warms up or when he or she stops eating, the seizures — and therefore the nodding — stop. And strangely, unfamiliar food does not seem to cause the seizures, as noted by a World Health Organization alert from June 2011 which observed that candy bars and non-traditional foods did not spur any sort of reaction.

As one would expect, children victimized by Nodding Disease find it difficult to eat, and therefore, suffer from malnourishment. Unfortunately, it seems likely that the seizures themselves also cause damage to the children in other ways, stunting their growth and leading to mental retardation. (Whether the syndrome is the cause of these problems is unknown, but the problems tend to correlate strongly with having the disease.) Even those for whom the seizure themselves cause little permanent damage are harmed significantly, as the seizures occur so often that going to school is simply not an option.

The cause of Nodding Disease is unknown. There are many theories: severe deficiencies of vitamin B6; exposure to toxic chemicals from wars waged long ago; a parasite in the region; or even tainted monkey meat. According to Reuters, there are 600 diseases which the Centers for Disease Control investigates, and the causes of only six — Nodding Disease being one of them — are unknown. In any event, the syndrome is, currently, seen as incurable — and spreading, at least locally to Uganda. Most northern Ugandan communities have at least one child afflicted with the syndrome. Some communities have been hit incredibly hard — as the Global Post recently noted, one particular Ugandan school district has 250 students and and incomprehensible 59 of them have contracted Nodding Disease.

Bonus fact : In most cultures, an up-and-down head nod means “yes” while a right-to-left shake means “no.” According to Cecil Adams of The Straight Dope, this is not quite true everywhere, and in Bulgaria specifically, it’s reversed: a nod means “no” while the shake means “yes.”

From the Archives: Laughing to Death: Another strange disease with an unexpected symptom.

Related: “Living with Bad Surroundings: War, History, and Everyday Moments in Northern Uganda” by Sverker Finnstrom. Two reviews averaging four stars. The negative (3 star) review disliked the book because it is written for “the very dedicated and interested reader or scholar” as it provides “almost everything they might want to know about the conflict” in the region. This seems to be a good thing, especially given the Joseph Kony stories and controversies traveling around in recent days. This book may be the closest one can get to a complete story (as of its publication date in 2008).