Blue-green algal poisoning

Also known as cyanobacteria

Description

Potentially toxic cyanobacteria, or blue-green algae, may form dense blooms in fresh water bodies. This may be seen as a thick green coat or scum within the upper water layer and surface.  Blooms are mainly a problem in late summer and autumn.  They are associated with nutrient over-enrichment due to factors such as animals defecating and urinating in the water or fertiliser run-off.  Many blooms are not toxic, but all should be considered potentially so.  A range of cyanobacterial genera and species have been described including Microcystis aeruginosa and Anabaena circinalis.  Different cyanobacteria may produce hepatoxins and/or neurotoxins.

Affected animals may be found dead. Clinical signs due to neurotoxins may include: muscle tremor, staggering, salivation, hyperaesthesia, diarrhoea and recumbency. Clinical signs due to hepatotoxins may include: anorexia, dehydration, jaundice, hypersensitivity or stupor, photosensitivity and recumbency.

Diagnosis and tests available

Diagnosis

Diagnosis is based on the visible presence of an algal bloom in animals’ drinking water confirmed by microscopic examination for blue green algae.

Test available

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Specimen requirements

Further information

NSW DPI general information on blue-green algae.

Note

Microscopic confirmation of the presence of cyanobacteria indicates the possibility of cyanobacterial poisoning, but does not confirm that the bloom is toxic.