anatoxina

Anatoxins are a group of potent neurotoxins produced by cyanobacteria, commonly associated with freshwater harmful algal blooms. The most studied members are anatoxin-a and anatoxin-a(s). These compounds can act rapidly and may pose risks to people, animals, and wildlife during bloom events.

Anatoxin-a acts as a nicotinic acetylcholine receptor agonist, causing sustained depolarization and neuromuscular blockade. Anatoxin-a(s) is a potent acetylcholinesterase inhibitor, which increases acetylcholine levels at synapses and can lead to a different pattern of cholinergic toxicity. Both mechanisms disrupt neuromuscular transmission and can result in weakness, paralysis, or respiratory failure.

These toxins occur in cyanobacterial blooms in lakes, rivers, and reservoirs and can contaminate drinking water and recreational waters. Exposure can occur through ingestion, inhalation of aerosols, or skin contact. Animals such as livestock and pets are particularly at risk during outdoor exposure to bloom-affected waters.

Symptoms typically appear quickly, from minutes to a few hours after exposure, and may include dizziness, numbness, headaches, vomiting, tremors, and weakness. In severe cases, respiratory failure and death can occur if access to adequate breathing support is not provided.

Detection relies on water testing and analytical methods such as chromatography coupled with mass spectrometry. There is no widely approved antidote for anatoxin-a; management is supportive, focusing on maintaining airway and respiration. For anatoxin-a(s) exposure, treatment follows protocols for acetylcholinesterase inhibitors, including the use of antidotes for muscarinic symptoms and respiratory support when needed.

Prevention centers on monitoring cyanobacterial blooms, implementing effective water treatment barriers, and issuing advisories to avoid contaminated waters. See also cyanotoxins and safe drinking water guidelines.