Algal toxins and water‐based diseases

Waterborne diseases are usually caused by infectious microorganisms. However, an intermittent but widespread source of water‐based diseases are the exotoxins produced by several marine and freshwater algae species. Marine algal toxins come from dinoflagellates and cyanobacteria (blue‐green algae). The main di‐noflagellate genera involved are Gonyaulax, Protogonyaulax, Gymnodinium, and Gambierdiscus. Known toxic marine cyanobacteria include Lyngbya, Schizothrix, and Oscillatoria. Toxic signs of these marine toxins are varied but involve mainly neuro‐ and dermatoxicity. A few freshwater algal toxins are produced by dinoflagellates and haptophytes but the majority are formed by “water bloom”; species of cyanobacteria. Toxic blooms of these cyanobacteria can be found in several types of water bodies. The main toxic genera are Microcystis, Anabaena, Aphanizomenon, and Oscillatoria. Toxins produced are neurotoxic alkaloids and hepatotoxic peptides. Human poisonings from algal toxins can be from ingestion of contaminated shellfish, fish, and drinking water or by contact with the algae in recreational water supplies.