Summary about Disease
Paralytic Shellfish Poisoning (PSP) is a severe illness caused by consuming shellfish contaminated with potent neurotoxins called saxitoxins. These toxins are produced by certain species of algae, particularly dinoflagellates, during algal blooms (often called "red tides"). PSP affects the nervous system, potentially leading to paralysis and respiratory failure.
Symptoms
Symptoms typically appear within minutes to a few hours after consuming contaminated shellfish. Common symptoms include:
Tingling or numbness of the lips, tongue, face, and extremities (fingers and toes)
Headache
Dizziness
Nausea, vomiting, and diarrhea
Muscle weakness
Difficulty breathing
In severe cases, paralysis and respiratory arrest can occur.
Causes
PSP is caused by eating shellfish (such as mussels, clams, oysters, scallops, and cockles) that have accumulated saxitoxins. These toxins are produced by certain types of algae, especially dinoflagellates from the Alexandrium, Gymnodinium, and Pyrodinium genera. Shellfish filter-feed, ingesting these algae and concentrating the toxins in their tissues. Human consumption of these contaminated shellfish leads to PSP.
Medicine Used
There is no specific antidote for saxitoxin. Treatment for PSP is primarily supportive, focusing on managing symptoms and preventing complications. This includes:
Respiratory support: Mechanical ventilation (breathing machine) may be necessary if the person is having difficulty breathing or experiencing respiratory paralysis.
Gastric lavage: If the patient presents soon after ingestion, gastric lavage (stomach pumping) might be considered to remove any remaining contaminated shellfish from the stomach.
Activated charcoal: Administered to help absorb any remaining toxin in the digestive system.
Supportive care: Monitoring vital signs (heart rate, blood pressure, oxygen saturation) and providing supportive care to maintain bodily functions.
Is Communicable
No, Paralytic Shellfish Poisoning is not communicable. It cannot be spread from person to person. It is solely caused by consuming contaminated shellfish.
Precautions
Heed warnings: Pay attention to public health advisories and warnings regarding shellfish consumption in specific areas.
Buy from reputable sources: Purchase shellfish only from licensed and reputable seafood dealers.
Proper cooking: Cooking shellfish does not destroy saxitoxins. Therefore, it does not make contaminated shellfish safe to eat.
Avoid harvesting during red tides: Do not harvest or consume shellfish from areas experiencing red tides or algal blooms.
Monitor your health: If you suspect you have consumed contaminated shellfish, seek immediate medical attention, especially if you experience any symptoms of PSP.
Check with local authorities: Contact your local health department or fisheries agency for information on shellfish safety in your area.
How long does an outbreak last?
The duration of a PSP outbreak depends on the duration and intensity of the harmful algal bloom (HAB) that produces the toxins. Outbreaks can last for several weeks to months, coinciding with the bloom's presence. Once the bloom subsides and toxin levels in shellfish decrease to safe levels, the outbreak ends.
How is it diagnosed?
PSP is diagnosed based on:
Clinical symptoms: The presence of characteristic symptoms such as tingling/numbness, muscle weakness, and respiratory difficulty, especially after shellfish consumption.
Patient history: A history of recent shellfish consumption, particularly from an area known to have PSP outbreaks.
Laboratory testing: Samples of the suspected shellfish can be tested for the presence and concentration of saxitoxins. Urine or vomit samples from the patient can also be tested, but this is less common.
Timeline of Symptoms
Minutes to 2 hours: Onset of symptoms typically occurs within minutes to 2 hours after consuming contaminated shellfish.
Initial symptoms: Tingling or numbness around the lips, tongue, and fingertips is often the first sign.
Progression: Symptoms can progress to include headache, dizziness, nausea, vomiting, and muscle weakness.
Severe cases: In severe cases, paralysis and respiratory failure can develop within a few hours.
Recovery: Recovery time varies depending on the amount of toxin ingested and the severity of the poisoning. Mild cases may resolve within a few days, while severe cases can take weeks or even months for full recovery.
Important Considerations
Severity varies: The severity of PSP depends on the amount of toxin ingested, the individual's sensitivity to the toxin, and their overall health.
Vulnerable populations: Children, the elderly, and individuals with underlying health conditions may be more vulnerable to the effects of PSP.
Global distribution: PSP occurs worldwide, particularly in coastal areas with frequent algal blooms.
Public health significance: PSP is a significant public health concern due to the potential for severe illness and death.
Monitoring programs: Many countries have monitoring programs in place to test shellfish for saxitoxins and issue warnings when levels exceed safe limits.