A scanning electron microscope image of Karenia brevis, the algae responsible for producing red tides in the Gulf of Mexico, and a computer model of brevetoxin that highlights the two reactive sites that bind DNA. Courtesy of John Ramsdell, photo by Karen Steidinger
Neurotoxic Shellfish Poisoning
This disease is associated with Brevetoxins. Blooms of the associated phytoplankton are highly distinctive (true red tides), are seasonal and can last for many months.
Blooms have been known off the coast of Florida for centuries, but in recent decades have also been recorded off other parts of the US east coast and New Zealand.
Symptoms are milder that PSP, but blooms can be so extensive that surf action can lead to aerosols carrying the toxin carried by wind up to 100km inland.
Symptoms include shortness of breath, and eye irritation. These blooms have further effects of ecology by causing massive fish kills, which when rotting, can lead to extensive areas subject to anoxia.
There are well characterized disease syndromes associated with contaminated shellfish, one of them being Paralytic shellfish poisoning (PSP).
Known to be caused by eating shellfish and other organisms which have built up toxins through filter feeding.
There are five species of dinoflagellate associated with PSP including Alexandrium catanella (pictured above) and all produce one or more toxins known as Saxitoxins.
PSP has a dramatic onset (within minutes of consumption):
1. Tingling around lips
2. Numbness of face & neck
3. Nausea, headache and difficulty in species
4. Muscular and respiratory paralysis (!)
The mortality rate can be >10 % if there are no access to medical services.
But the good news is, if someone can keep your heart beating and help with artificial respiration, your body will detoxify the saxitoxin and there are no long-lasting effects. If you make it to a hospital, they’ll be able to help further by pumping your stomach and administering charcoal.