Which organism is associated with Amnesic Shellfish Poisoning in humans?

• A. Dinophysis
• B. Pseudo-nitzschia
• C. Alexandrium
• D. Vibrio vulnificus

Answer: (B)

Amnesic Shellfish Poisoning is caused by a neurotoxin, domoic acid, produced by certain diatoms that bloom in the water. Shellfish are filter feeders, so they accumulate the toxin as they filter water containing these diatoms. The most common organism linked to this toxin is Pseudo-nitzschia, a diatom genus that produces domoic acid during blooms. When people eat contaminated shellfish, domoic acid can affect the brain, especially the hippocampus, leading to memory loss and other neurological symptoms.

Dinophysis is associated with toxins that cause Diarrhetic Shellfish Poisoning, which presents mainly with gastrointestinal symptoms like diarrhea and abdominal cramps, not memory loss. Alexandrium produces saxitoxins that cause Paralytic Shellfish Poisoning, with numbness, tingling, and potential respiratory paralysis, not amnesia. Vibrio vulnificus is a bacterium that can cause severe infection from contaminated seafood, particularly in vulnerable individuals, but it is not a shellfish toxin responsible for ASP.

So the organism most closely linked to Amnesic Shellfish Poisoning is Pseudo-nitzschia.