Shellfish Poisoning

Paralytic Shellfish Poisoning (PSP) is a serious illness that is caused by eating shellfish contaminated with single-celled swimming algae called Alexandrium. These tiny living things produce harmful poisons called saxitoxins. When eaten by humans or animals, these affect the nervous system and can be life-threatening.

PSP is named for the main effect of this poison: paralysis, which means being unable to move. 

Amnesic Shellfish Poisoning (ASP) is a serious sickness that happens when people eat shellfish that have harmful tiny plants called diatoms in them. In particular, diatoms from the genus Pseudo-nitzschia make a poison called domoic acid (DA).

ASP is named for one of the effects of this poison, short-term memory loss.

Diarrhetic Shellfish Poisoning (DSP) causes stomach problems that can feel really bad, but they are not life-threatening. Most people feel better in a few days. DSP happens from eating shellfish that have harmful algae of a type (genus) called Dinophysis.

DSP is named after one of the symptoms it causes, diarrhea.

At first, people with PSP might feel a tingling sensation in their lips and tongue. This can happen just a few minutes after eating bad shellfish, or it might take an hour or two to show up.

As time goes on, the tingling can spread to fingers and toes. This can lead to trouble moving the arms and legs and might make it hard to breathe.

Some people also feel like they’re floating or feel sick to their stomachs.

The muscles in the chest and belly can stop working. If someone gets a lot of toxins, they could have serious breathing problems that can be very dangerous or deadly within just two hours. 

Diagnosis is based on a history of recently eating shellfish plus showing these symptoms. Blood or urine may be tested for toxins that cause PSP.

Symptoms include vomiting, nausea, diarrhea, and stomach cramps within 24 hours of eating shellfish.

In more serious cases, symptoms involving the nervous system start happening within 48 hours.

These include headaches, feeling dizzy, confusion, getting lost, forgetting things (short-term memory loss), weak muscles, seizures, a lot of mucus when breathing, heart problems, or passing out. The toxin can even cause death in this time.

Short term memory loss is permanent. That is why this type of poisoning is called "amnesic."

Diagnosis is based on symptoms, a history of eating shellfish and lab testing for domoic acid, the poison that causes ASP. Labs can test human urine or food samples.

DSP causes stomach problems like chills, nausea, vomiting, belly cramps, and diarrhea.

Symptoms usually start between 30 minutes and 15 hours after eating contaminated shellfish.

Signs and symptoms are usually mild, but can be worse depending on how much was eaten. People usually recover in a few days.

It is diagnosed based on symptoms and a history of eating shellfish.