saxtoksiini

Saxtoksiin, or saxitoxin (STX), is a potent neurotoxin produced by certain marine dinoflagellates and freshwater cyanobacteria. It is the causative agent of paralytic shellfish poisoning (PSP) and can accumulate in filter-feeding shellfish such as clams, mussels, oysters, and scallops during algal blooms.

The toxin acts by blocking voltage-gated sodium channels, preventing the propagation of action potentials in nerves and muscles. This disruption can cause numbness, tingling, dizziness, and weakness, progressing to severe paralysis and respiratory failure in high doses. Saxtoksiin is heat-stable, and cooking shellfish does not reliably destroy the toxin. There is no antidote; management relies on supportive care, including respiratory support if needed.

Humans are mainly exposed through consumption of contaminated shellfish harvested during algal blooms. Symptoms typically appear within minutes to hours after ingestion and may start with perioral numbness and paresthesias, followed by weakness and, in severe cases, respiratory compromise. Regulatory agencies around the world set limits for saxitoxin equivalents in shellfish to protect public health, and monitoring programs aim to prevent contaminated products from reaching consumers. Detection methods include LC-MS/MS, high-performance liquid chromatography, and immunoassays; historically, the mouse bioassay was used.

Ecology and public health considerations emphasize that saxtoksiin production is linked to environmental conditions such as water temperature, salinity, and nutrient loads that drive algal blooms. Monitoring, rapid response, and shellfish avoidance during bloom events remain key strategies to reduce PSP incidents.