Anatoxinaa

Anatoxinaa is a term used to describe a group of potent neurotoxins produced by certain freshwater cyanobacteria, most notably anatoxin-a and related compounds. Anatoxin-a is an alkaloid that acts as a highly active agonist of nicotinic acetylcholine receptors at the neuromuscular junction, causing rapid nerve stimulation followed by paralysis and potentially respiratory failure. Related toxins, such as anatoxin-a(s), function through different mechanisms (anatoxin-a(s) inhibits acetylcholinesterase), leading to a cholinergic crisis.

These toxins are associated with cyanobacterial blooms in lakes and rivers worldwide. They can contaminate drinking water and aquatic food sources, with exposure occurring through ingestion of contaminated water, fish, or shellfish, or, in some cases, skin contact.

Clinical effects are typically rapid, with symptoms developing within minutes to a few hours after exposure. Anatoxin-a–related signs include muscle weakness, tremors, salivation, vomiting, seizures, and respiratory collapse. Anatoxin-a(s) presents with overstimulation followed by cholinergic symptoms such as excessive secretions, sweating, pinpoint pupils, slowed heart rate, and diarrhea. There is no widely available antidote; treatment is supportive, focusing on securing the airway and ventilation, decontaminating exposure, and managing seizures or cardiac issues as needed.

Prevention and monitoring efforts are led by public health agencies that track cyanobacterial blooms and issue advisories when toxins may be present. Water treatment can reduce toxin levels with appropriate filtration, oxidation, or activated carbon. People and animals should avoid contact with or ingestion of water during blooms and heed local health warnings.