River blindness goes beyond the eye: autoimmune antibodies, cross-reactive with Onchocerca volvulus antigen, detected in brain of patients with Nodding syndrome
Nodding syndrome (NS) is a neurological disorder primarily characterized by paroxysmal head nodding seizures, affecting previously healthy children at the age between 3–18 years (1,2). Growing numbers of patients with NS were documented since the early 2000s in three distinct areas in the southern Sudan (3,4), southern Tanzania (1) and northern Uganda (5,6). In retrospect, NS was also found in western Uganda (7,8) and suspected cases were reported from Liberia (9) and Cameroon (10). In many NS patients, initial head seizure are followed by other seizures types, progressing physical and cognitive deterioration, and death (6,8). To date, the exact causation of NS is not clarified, but epidemiological and case-control studies have shown a consistent correlation between NS and infection with Onchocerca volvulus (O. volvulus), a parasite known as the cause of river blindness in large parts of tropical Africa (2,4,11,12). Because imaging studies and analysis of cerebrospinal fluid (CSF) failed to demonstrate the parasite in the central nervous system (CNS) of NS patients (1,4-6,13) it was suggested that an immunological process related to O. volvulus could play a role in the origination of NS (14,15).