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Biological Hazard – Paralytic shellfish poisoning (PSP)/red tide: Public Health Alert, Washington State

2016/04/09

PARALYTIC SHELLFISH POISONING/RED TIDE – USA: (WASHINGTON) ALERT
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Published Date: 2016-04-08 09:27:23
Subject: PRO/AH/EDR> Paralytic shellfish poisoning/red tide – USA: (WA) alert
Archive Number: 20160408.4146402

Date: Wed 6 Apr 2016
Source: King-TV, Associated Press (AP) report [edited]

Health officials have closed the recreational harvest for all molluscan shellfish on beaches in northern Washington state. The closure came after unsafe levels of paralytic shellfish poisoning biotoxin were detected.

The Washington State Department of Health closed the harvest for beaches from Sandy Point north to the Canadian border. Point Roberts beaches will be closed as a precaution until shellfish samples can be obtained to determine biotoxin levels.

Molluscan shellfish include clams, mussels, oysters and scallops. Shellfish sold in restaurants and markets have been tested and are safe to eat.

Communicated by:
ProMED-mail from HealthMap Alerts
<promed@promedmail.org>

[It sounds like they are monitoring things closely. They have closed the harvest areas prior to a catastrophic illness.

Dinoflagellates produce a number of toxins. How the disease is designated or named tends to reflect the organism responsible.

Paralytic shell fish poisoning is sometimes referred to as a “red tide”. Red tide or harmful algal blooms (HABs) are events in which single-celled protists, dinoflagellates, proliferate rapidly and accumulate in the water column. These events are associated with wildlife mortalities because, under certain circumstances, these organisms can produce potent toxins. Normally, these toxins enter the food web when they are consumed by filter feeding animals — such as clams, oysters, mussels — in which the toxins bioaccumulate.

One interesting note is that both people and dogs can be sensitive to the spray effects associated with a red tide bloom. Dogs react in much the same fashion as people, with eye irritation, nose, and respiration irritation, and some dogs will have inflamed ears, and irritated skin.

Red tide is caused by several toxic algae. Depending upon the toxin, it is also known as paralytic shellfish poisoning (PSP), because it causes shellfish for consumption to be toxic.

The _Alexandrium_ genus is found in coastal waters high in nitrogen content. These organisms produce a neurotoxin, like many of the organisms capable of causing paralytic shellfish poisoning (PSP). The neurotoxin is considered fatal for humans consuming contaminated shellfish and may be dangerous to humans and animals who swim in waters that are “blooming” with the organisms. Ocean spray containing the organisms may also cause illnesses, including rashes and eye irritation in people. Some species of this genus are capable of causing “red tide” that may be visible for long distances along a coastline.

PSP is a significant problem in several geographic areas, especially on both the east and west coasts of the United States. Produced by several closely related species in the genus _Alexandrium_, PSP toxins are responsible for persistent problems due to their accumulation in filter-feeding shellfish, but they also move through the food chain, affecting zooplankton, fish larvae, adult fish, and even birds and marine mammals.

_Alexandrium_ blooms generally do not involve large-cell accumulations that discolor the water and may instead be invisible below the water surface. Low-density populations can cause severe problems due to the high potency of the toxins produced. Furthermore, _Alexandrium_ spp can grow in relatively pristine waters, and it is difficult to argue that anthropogenic nutrient inputs are stimulating the blooms. These characteristics are important when considering mitigation and control strategies.

Paralytic shellfish poisoning (PSP) is a significant problem in many areas. Caused by several closely related species in the genus _Alexandrium_, PSP toxins are responsible for persistent problems due to their accumulation in filter feeding shellfish, but they also move through the food chain, affecting zooplankton, fish larvae, adult fish, and even birds and marine mammals.

It is likely that seasonally recurring outbreaks of PSP are linked to the existence of a dormant cyst stage in the _Alexandrium_ life history. This strategy allows the species to deposit dormant cells in sediments where they survive through harsh winter conditions and then germinate to initiate new outbreaks in subsequent years. Long-term climatic variability, which affects temperature, upwelling, and currents or allows cysts to survive in areas where they did not before, may be factors in extensions.

Shellfish that have caused this disease include mussels, cockles, clams, scallops, oysters, crabs, and lobsters. Symptoms begin anywhere from 15 minutes to 10 hours after eating the contaminated shellfish, although usually within 2 hours. Symptoms are generally mild, and begin with numbness or tingling of the face, arms, and legs. This is followed by headache, dizziness, nausea, and muscular incoordination. Patients sometimes describe a floating sensation. In cases of severe poisoning, muscle paralysis, and respiratory failure occur, and in these cases death may occur in 2 to 25 hours.

Often PSP is associated with red tides or algal blooms. Red tide is caused by an organism called _Karenia brevis_, which in high concentrations can make the water look red. The organism releases a toxin that paralyzes the respiratory system of fish and other marine life. _K. brevis_ is a marine dinoflagellate common in Gulf of Mexico waters and is the organism responsible for Florida red tides. The toxin it produces is called brevetoxin, which can cause neurotoxic poisoning.

Airborne toxins, water spray, and splashes in an outbreak have kept people from beaches while leaving others with irritated eyes and throats. Red tide irritates the skin of people exposed to it and can cause itchy eyes, scratchy throats, and coughs. Harvesting from affected areas for personal consumption is discouraged. Red tide poisoning symptoms include nausea and dizziness and may last for several days.

Previously, the organism causing red tide was known as _Gymnodinium breve_, but it has been reclassified in the taxonomy of dinoflagellates. Its new name — _Karenia brevis_ — was chosen in honor of Dr Karen Steidinger, a prominent red tide scientist from the Florida Marine Research Institute in St Petersburg, Florida.

Shellfish that have caused this disease include mussels, cockles, clams, scallops, oysters, crabs, and lobsters. Symptoms begin anywhere from 15 minutes to 10 hours after eating the contaminated shellfish, although usually within 2 hours. Symptoms are generally mild, and begin with numbness or tingling of the face, arms, and legs. This is followed by headache, dizziness, nausea, and muscular incoordination. Patients sometimes describe a floating sensation. In cases of severe poisoning, muscle paralysis and respiratory failure occur, and in these cases, death may occur in 2 to 25 hours. – Mod.TG

A HealthMap/ProMED-mail map can be accessed at: http://healthmap.org/promed/p/248.]

See Also

Paralytic shellfish poisoning – Australia: (WA) alert 20150919.3655948
Paralytic shellfish poisoning – UK: (Scotland) 20150513.3359073

2014
—-
Paralytic shellfish poisoning – China: (HK) 20141011.2853909
Paralytic shellfish poisoning – USA: (AK) 20140623.2559312

2013
—-
Paralytic shellfish poisoning – Philippines: (BA) alert 20131122.2066016
Botulism, paralytic shellfish poisoning – Canada: (BC) alert 20131018.2008893
Paralytic shellfish poisoning – Australia: (WA) alert 20130919.1954502
Paralytic shellfish poisoning – UK: (Scotland) 20130701.1800637
Paralytic shellfish poisoning – USA: (AK) 20130614.1771968

2012
—-
Paralytic shellfish poisoning – New Zealand (03): (BP) 20121221.1462922
Paralytic shellfish poisoning – New Zealand: (BP) 20121219.1458517
Diarrheal shellfish poisoning – Ireland: (west) alert 20120814.1243602
Undiagnosed biotoxin – USA: (WA), shellfish harvest suspended, RFI 20120511.1129484

2011
—-
Paralytic shellfish poisoning – Philippines: (BA) 20111124.3436
Paralytic shellfish poisoning – USA: (AK) 20111118.3395

2010
—-
Paralytic shellfish poisoning – Canada: (BC) warning 20101008.3665
Paralytic shellfish poisoning – USA: (ME) warning 20100714.2353
Paralytic shellfish poisoning – China (03): (GD) scallops 20100524.1718
Paralytic shellfish poisoning – China (02): (HK,MC) scallops, alert 20100519.1653
Paralytic shellfish poisoning – China: (HK) scallops, alert 20100518.1627
………………………………………….sb/tg/mj/lm

Source:
A ProMED-mail post
ProMED-mail is a program of the International Society for Infectious Diseases


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