Four relevant references below. If cyanobacteria can reside in pig intestine, why not in human intestine?
Environmental and Occupational Exposures and Amyotrophic Lateral Sclerosis in New England
Neurodegener Dis. 2017;17(2-3):110-116.
A cluster of amyotrophic lateral sclerosis in New Hampshire: a possible role for toxic cyanobacteria blooms.
Amyotroph Lateral Scler. 2009;10 Suppl 2:101-8.
Assessing Cyanobacterial Harmful Algal Blooms as Risk Factors for Amyotrophic Lateral Sclerosis.
Neurotox Res. 2018 Jan;33(1):199-212.
Early Postnatal Diets Affect the Bioregional Small Intestine Microbiome and Ileal Metabolome in Neonatal Pigs.
J Nutr. 2017 Aug;147(8):1499-1509.