UAntwerp researchers find cause for mysterious nodding syndrome

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For decades, researchers have been trying to uncover the cause of nodding syndrome, a mysterious and deadly form of epilepsy that only affects children on the African continent. In a collaboration between Belgian and African scientists, researchers from the University of Antwerp have now discovered the root cause of the disease. In a cascade of events, nodding syndrome is triggered by another disease called river blindness, which in turn is caused by parasitic worms spread by blackfly bites. As complicated as it sounds, this is great news for the children, as it means that nodding syndrome can easily be controlled by administering the anti-parasitic drug ivermectin and exterminating blackflies.

Since the 1960s, thousands of children in poor, war-torn regions of East Africa have developed epilepsy-like seizures characterized by a nodding of the head. Over time, these seizures worsen, cognitive problems develop, and the victims often tragically pass away. Typically, nodding syndrome affects children between the ages of 5 and 15 years old, and is only one of a range of epileptic diseases common in this part of the world.

For a long time, these mysterious epileptic illnesses left researchers bewildered as to their root cause. At the University of Antwerp, Prof Robert Colebunders has been working together with African scientists on a 5-year project to elucidate the root cause of nodding syndrome and attempt to find a way to stop it.

They had one key clue: areas with nodding syndrome also had high rates of river blindness, another disease caused by the parasitic worm Onchocerca volvulus. Spread through the bites of blackflies, the World Health Organization estimates that at least 18 million people are infected by this disease.

A deadly cascade of events

Researchers have long throught that the high rates of epilepsy in Africa might be related to the parasitic worm that causes river blindness. Under the supervision of Professor Robert Colebunders, Cameroon researcher Dr Joseph Nelson Siewe Fodjo is part of the UAntwerp team that has confirmed this link:

“The study confirmed the high incidence of epilepsy in areas where river blindness is not under control, such as Cameroon, the Democratic Republic of Congo and South Sudan. In some villages, up to 6% of the population had it. We discovered various forms of epilepsy associated with river blindness: mainly epilepsy with generalised seizures, but also nodding syndrome and Nakalanga syndrome.”

The lynchpin in this epilepsy cascade seem to be the bites of the vectors spreading the parasitic worms, the blackflies:

“We saw otherwise healthy children between the ages of 8 and 12 suddenly develop epileptic seizures,” says Dr Siewe. “This often occurred in several children in the same family. The affected families usually lived close to breeding sites of the blackfly, the transmitter of the worm that causes river blindness. As many of them cannot afford treatment with anti-epileptic medication, people with epilepsy in these areas rarely live past the age of 30.”

A simple, lifesaving solution

There is good news in this newfound information: there may be a straightforward way to eliminate the neglected tropical disease. Dr Siewe explains the simple remedy:

“This form of epilepsy is perfectly preventable, simply by distributing ivermectin – a drug that cures river blindness – annually to the entire population. Twice a year would be even better, especially in combination with efforts to destroy the breeding grounds of the blackfly and eradicate river blindness altogether.”

Read this previous BioVox article to learn more about another insect vector for disease: mosquitoes

Ivermectin is an antiparasitic drug, whose discoverers Campbell and Ōmura were awarded the 2015 Nobel Prize. The cheap drug is provided for free by producer Merck for the treatment of river blindness, but it may be used as a prophylactic to prevent nodding syndrome as well, as past campaigns have shown. After the Ugandan government stepped up ivermectin treatment, new cases of nodding syndrome plunged to nearly zero, as published in The Lancet earlier this year. Colebunders shares his hopes for the future:

“If you eliminate Onchocerca worm infections in an area, nodding syndrome disappears. We now have very strong evidence of the epidemiological link between the parasitic worm and nodding syndrome, as well as other forms of epilepsy. The only thing we don’t know is the exact disease mechanism; that research is still ongoing.

But we now know that we can eliminate this disease, that we can prevent children from developing nodding syndrome and other types of epilepsy. Nodding syndrome is really only the ears of the hippopotamus: the whole hippo is really all of the types of epilepsy caused by these parasitic worm infections which is a much bigger problem than just nodding syndrome. We estimate that 300 000 people in the world suffer from these types of epilepsy, that we now know could have been prevented. There is an urgent need to step up efforts to alleviate and prevent the immense suffering of families with children with epilepsy in many regions of Africa.”