Poisoned by the microalgae Ostreopsis?

Since 2021, microscopic algae of the genus ostripsis It appeared on the Basque coast. This algae can present a health hazard to swimmers as well as to people who frequent the waterfront, and is under enhanced monitoring by the Regional Health Agency (ARS) of New Aquitaine. explanations.

tropical algae ostripsis It is located on the French coast

In the summer of 2021, the first flowers of this will appear microscopic algaeor microalgaefrom a kind of ostripsishave been reported on the Basque coast. Microscopic and therefore invisible to the naked eye, these algae can by reproduction give a Mineral salt water taste and fig Gelatinous films On rocks and macroalgae (macroalgae). Beyond its appearance, the toxins it releases are above all a problem. these toxins With winds and currents, not only in the water, but also in the air.

the toxins it produces ostripsis It can thus affect swimmers, people on sand or rocks, but also walkers by the sea. Of tropical origin, microalgae ostripsis The Mediterranean arrived about twenty years ago with warming temperatures and more recently the Basque coast. As they multiply, these microalgae produce large amounts of toxins, which can cause multiple symptoms in exposed people:

• annoying cough
• Runny nose;
• sore throat.
• skin irritation;
• Burning or irritation in the eye.
• nosebleeds
• difficulty breathing
• Fever ;
• shivering;
• myalgia;
• headache;
• nausea.

Microalgae under close watch on the Basque coast

The first signs appear within the first six hours after exposure to toxinsostripsis It usually goes away within a few days without complications. But such symptoms are enough to spoil a trip to the seaside. Since the first reports in 2021, a specific monitoring plan To identify microalgae and inform the population. This plan is coordinated among others by ARS in New Aquitaine, IFREMER, Poison Control Centers, Urban Community of Basque Country and Rivage Pro Tech.

Microalgae are looked for in samples of seawater and macroalgae, microalgae that grow on the surface of macroalgae. When the onset of reproduction is detected (when seawater temperature exceeds 20 °C), samples are condensed to better monitor the level of toxins. To inform the population, a poster and display were designed in four languages ​​(French, Basque, English, Spanish). A mobile application, Kalilo, has also been developed for the general public. in this time, Nearly 900 cases of poisoning with toxins fromostripsis It was recorded on the Basque coast. No cases have yet been detected for the 2023 season.

4 essential tips to protect yourself from itostripsis

What precautions should be taken to prevent poisoning if it spreads? ANSES has recently issued several recommendations for Protect yourself from toxinsostripsis in the event of microalgae infestation :

• systematically take a shower when returning from the beach or seashore (being a few meters from the shore can be enough to get poisoned) and wash your body and hair;
• eviscerate all caught fish, even the smallest (toxins accumulate in the digestive tract) before eating;
• Do not consume other seafood during this period (mollusks and crustaceans);
• Do not go to the beach for weak people (children and infants, the elderly, people with chronic diseases, etc.) and consult a doctor if unusual symptoms appear.

Symptoms disappear on their own within a few days, but a doctor should be consulted if signs of intoxication persist for more than 3 to 4 days or if they worsen, in particular, if there is significant difficulty in breathing, persistent, prolonged muscle pain. Generalized shaking or rash. Suspected poisoning can be reported to a poison control center who will indicate what action to take. Emergency services should only be contacted in an emergency.

Estelle B. Doctor of Pharmacy

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