New Brunswick Neurological Syndrome of Unknown Cause (NBNSUC) is a 'disease cluster' centered around the area of New Brunswick in Canada.

It's a severe, persistent disease which causes hallucinations, loss of motor control, blurred vision, muscle wastage, memory loss and other symptoms. As at 2024, around 200 people are known to have been affected.

It was originally thought to be related to Creutzfeldt-Jakob Disease ('Mad Cow Disease') which is associated with rogue prionsplugin-autotooltip__plain plugin-autotooltip_bigPrion replication

"Prions are infectious agents composed entirely of a protein material that can fold in multiple, structurally distinct ways, at least one of which is transmissible to other prion proteins, leading to disease in a manner that is epidemiologically comparable to the spread of viral infection. Prions composed of the prion protein (PrP) are believed to be the cause of transmissible spongiform encephalopathies (TSEs) among other diseases.". This has now been largely discounted, as no-one with the disease has tested positive to prions.

Research is currently focusing on Lytico-bodig disease, which principally affects residents of the island of Guam in Micronesia. Lytico-bodig also has an unknown cause, but is strongly suspected to be linked to toxins in diet - either from local cycad trees, or from toxic algae products via seafood.

In the case of NBNSUC, it has now been found that some carers have also developed symptoms. This could be caused by contagion, dietary factors, or some other environmental factor - e.g agricultural chemicals.

Further details : Public Health New Brunswick, Epidemiology and Surveillance Branch