Despite decades of research, no one has managed to figure out what’s causing the strange and deadly nodding syndrome. The search for answers could save thousands of lives – and may unlock new treatments for intractable diseases such as Alzheimer’s.

For the Wapogoro people, there are few worse fates than kifafa.

The tribe lives in the Mahenge highlands in deepest Tanzania: a land of rugged mountains, mist-capped forests and rare underground treasures, from fossils to glittering neon-pink gems. They have survived there in isolation for hundreds of years, quietly going about their lives and largely escaping the notice of the wider world.

Or that was the case, until a Norwegian doctor turned up in 1959. Louise Jilek-Aall was just 28 years old, fresh out of medical school and determined to set up a clinic in the area. But no sooner had she started seeing patients than she noticed something peculiar.

Nearly every day, children as young as two would turn up in her office with severe burns. In one case, a little girl was rendered completely unrecognisable; many others died from their wounds. The burns were often overlaid on webs of pale pink scars, which had built up after years of previous scorchings.

In fact, the youngest members of the tribe seemed particularly, some would say suspiciously, susceptible to a wide range of accidents, including regular drownings. When Jilek-Aall tried to find out what was going on, she met with fear and evasion. Even the relatives of affected children flatly refused to explain the sinister trend.

Eventually Jilek-Aall realised that her patients were having seizures, which they called kifafa – Swahili for “the little death” – and falling down. Sometimes they would land in the open hearths where they cooked their food. Occasionally they would end up in the river.

But the mystery didn’t end there. The same children also tended to have stunted growth, intellectual difficulties and characteristic mannerisms, such as an awkward gait and deadpan facial expressions. Most strikingly, there was the "head nodding"; several times a day, they would close their eyes and repeatedly drop their heads to their chests. The illness typically lasted for a number of years and ended with an early death.

Finally, though every member of the Wapogoro was afraid of kifafa to an almost feverish degree, the illness was practically unheard of elsewhere in Tanzania. This was even true of neighbouring tribes.

Nodding syndrome has since been found in pockets across east Africa, from South Sudan to northern Uganda, where it has devastated the lives of thousands of people. In each new location, it seems to appear out of nowhere. What could be behind this deadly plague? And how can we stop it?

To this day, no one knows what causes nodding syndrome. In the past, the illness was generally accepted to be a rare and enigmatic form of epilepsy. But now the latest research has hinted that it might be a neurodegenerative disease, which manifests as a combination of epilepsy and some symptoms of Parkinson’s and Alzheimer’s. In the end, its victims usually succumb to seizure-related complications, such as brain damage and accidents, or poor mental health and neglect.

The tantalising clue emerged from a 2018 study, which found that the brains of teenagers with the illness look remarkably similar to those of elderly patients with the latter two diseases. “It’s generated a new line of enquiry, because now we know that there is a certain type of brain damage occurring,” says Michael Pollanen, a pathologist at the University of Toronto who led the research. “You can think of it like this: if you can figure out what the type of brain damage is, maybe you’ll be able to work backwards to the cause.”

At the very least, the overlap with other diseases adds an extra sense of urgency to the research. Not only does nodding syndrome affect some of the most vulnerable people on the planet, but it may hold the key to understanding several disorders which have long eluded scientists.

BBC