We have described the above enigmatic disorder of young children in East Africa before; a degenerative brain disease characterised by repetitive nodding movement, an inability to swallow, and eventually global brain failure. Authors of a recent study hypothesised that the disease may be caused by an autoimmune response to the river blindness parasite. They detected auto-antibodies to the parasite more often in cases than age-matched controls from the same village. The antibody attacks various cell markers in the mouse brain among neural networks that are affected in nodding syndrome. But only about half the patients with nodding syndrome exhibited the antibodies. The authors speculate that a number of yet to be identified antibodies may also be involved. I wonder why the disease does not map onto the geography of river blindness, which appears to be much broader than that of nodding syndrome.
So, here is my hypothesis. Remember, a few News Blogs ago, I articulated a ‘three hits hypothesis’ as the cause of many diseases. One example was cytomegalovirus infection, which in the presence of the malaria parasite, and along with genetic predisposition, leads to Burkitt’s lymphoma. So I suspect that exposure to river blindness may be a sensitising event, and propose a search for a further exposure that is more specific to the ‘nodding syndrome belt’ extending from South Sudan, through Uganda to North Tanzania (see Figure).
Data on River Blindness taken from the World Health Organization.
— Richard Lilford, CLAHRC WM Director
- Chilton PJ. A Mysterious Disease with Unknown Cause. NIHR CLAHRC West Midlands News Blog. 27 June 2014.
- Johnson TP, Tyagi R, Lee PR, et al. Nodding syndrome may be an autoimmune reaction to the parasitic worm Onchocerca volvulus. Sci Transl Med. 2017; 9.
- Lilford RJ. Three Hits Hypothesis. NIHR CLAHRC West Midlands News Blog. 7 April 2017.