anatoxinaas

Anatoxinaas are a group of potent neurotoxins produced by certain cyanobacteria (blue-green algae) and, in some cases, other microorganisms. The best-studied members are anatoxin-a and anatoxin-a(S). Anatoxin-a is a fast-acting alkaloid that acts as a nicotinic acetylcholine receptor agonist, causing persistent depolarization of skeletal muscles and nerves. Anatoxin-a(S) is an organophosphate-like toxin that inhibits acetylcholinesterase, leading to cholinergic overstimulation.

Exposure to anatoxinaas typically occurs through ingestion of contaminated freshwater during cyanobacterial blooms, or through contact with contaminated water in recreational settings. Animals and livestock may be especially at risk, and humans can experience symptoms after drinking or swallowing contaminated water. Symptoms of anatoxin-a exposure can appear within minutes to hours and include dizziness, nausea, vomiting, dry mouth, blurred vision, muscular weakness, tremors, seizures, and in severe cases respiratory failure and death. Anatoxin-a(S)–related illness presents with muscarinic and nicotinic signs such as salivation, lacrimation, urination, defecation, bradycardia, bronchospasm, and weakness.

Detection and monitoring rely on chemical analysis of water samples, using methods such as LC-MS or immunoassays. Public health responses emphasize prevention and rapid response: closing affected water bodies, issuing advisories, and providing supportive medical care. There is no widely available specific antidote for anatoxin-a; treatment is supportive, including airway management and, for anatoxin-a(S) exposure, antidotes used for cholinesterase inhibitors (e.g., atropine and pralidoxime) as clinically indicated.

Prevention focuses on monitoring cyanobacterial blooms, implementing water treatment strategies, and following public health guidelines for safe drinking and recreational waters.