Rare Disease Mystery: Nodding Syndrome May Be Linked to Parasitic Worm

Rural Uganda village gathering

Caption: Village in the East Africa nation of Uganda
Credit: Centers for Disease Control and Prevention

In the early 1960s, reports began to surface that some children living in remote villages in East Africa were suffering mysterious episodes of “head nodding.” The condition, now named nodding syndrome, is recognized as a rare and devastating form of epilepsy. There were hints that the syndrome might be caused by a parasitic worm called Onchocerca volvulus, which is transmitted through the bites of blackflies. But no one had been able to tie the parasitic infection directly to the nodding heads.

Now, NIH researchers and their international colleagues think they’ve found the missing link. The human immune system turns out to be a central player. After analyzing blood and cerebrospinal fluid of kids with nodding syndrome, they detected a particular antibody at unusually high levels [1]. Further studies suggest the immune system ramps up production of that antibody to fight off the parasite. The trouble is those antibodies also react against a protein in healthy brain tissue, apparently leading to progressive cognitive dysfunction, neurological deterioration, head nodding, and potentially life-threatening seizures.

The findings, published in Science Translational Medicine, have important implications for the treatment and prevention of not only nodding syndrome, but perhaps other autoimmune-related forms of epilepsy. As people in the United States and around the globe today observe the 10th anniversary of international Rare Disease Day, this work provides yet another example of how rare disease research can shed light on more common diseases and fundamental aspects of human biology.

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From Uganda to NIH, to Solve a Seizure Mystery

Ugandan family members in a conference room

Caption: From left, translator Irene Nakamya; Alice Alanyo and infant son Hassan Komakech; Concy Lamunu and infant son Jovan Lokpol; Balbina Lamon; Domasco Okenyy; and translator Tom Azalia during the Ugandan family’s visit to the NIH Clinical Center in May 2014.
Credit: Maggie Bartlett, National Human Genome Research Institute, NIH

In 2012, NIH researcher Avindra Nath traveled to Uganda to investigate a mysterious illness striking children between ages 5 and 15 in Acholi—a remote region in the north of that African nation. More than 3,000 children in Acholi and villages in nearby Southern Sudan were suffering from “nodding syndrome.” Named for the drooping, or nodding, head typically seen in patients, the condition is characterized by seizures, staring, and varying degrees of mental retardation.

Dr. Nath, a neurologist and clinical director at NIH’s National Institute of Neurological Disorders and Stroke, and Dr. Thomas Nutman, an expert in parasitic diseases from our National Institute of Allergy and Infectious Diseases, along with experts from the Centers for Disease Control and Prevention (CDC) and the World Health Organization, have joined with experts in Uganda to try to identify the cause of this disease. If you are wondering why the NIH would be interested in a mysterious syndrome seen in this region of the world, it is because any disease that spreads rapidly is a global threat.

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