Since 2021, the proliferation of Ostreopsis microalgae has caused nearly 900 poisonings in the Basque Country. To prevent the situation from degenerating again this year, the National Health Security Agency (ANSES) unveiled measures on Tuesday, June 20, 2023 to protect the most vulnerable populations from these microalgae.
Who is the culprit? Ostreopsis is the name given to a microscopic algae of tropical origin. She arrived in the Mediterranean about twenty years ago. In recent years, it has been found mainly on the Basque coast and proliferates especially during the summer months when the water is above 20 degrees.
Bad news, it is enough to be located a few meters from the beach where they are installed to be the victim of contamination. Bathers, walkers, no one is safe from poisoning, because breathing sea spray can have serious consequences. Indeed, this algae produces toxins that can generate different symptoms in patients: flu symptoms, skin irritations, gastric disorders… So many signs that appear a few hours after contact with the algae.
How to recognize her on the beach? “Ostreopsis can accumulate on the surface of the water to form algal blooms. These blooms can create brown slicks that can reach several square meters. These can however disappear quickly and it is not because they are not visible that there is no risk”, illustrates ANSES. Do you feel a metallic taste in your mouth? Caution, it is a distinctive sign of the presence of this microalgae.
So how do you deal with this intoxication? The Health Agency recommends that those most at risk (such as lifeguards and restaurateurs) follow certain precautionary measures. Indeed, regular exposure can cause a lengthening of the duration of symptoms. Accordingly, ANSES encourages those affected to report symptoms to occupational medicine. “People who have breathing problems are most at risk of developing symptoms. They should avoid being close to the coast when there is a proliferation of Ostreopsis,” warns Carole Catastini, who coordinated the expertise at ANSES.
The Health Agency also mentions the possibility of adjusting working hours to limit the exposure of those who work near contaminated areas. In addition, the people in charge of water withdrawals must wear protective equipment consisting of masks and gloves. Experts also encourage checking all beaches where there are water activities (swimming, surfing or sailing).
Should we be wary of eating shellfish and fish? Although cases of food poisoning have been reported, the link with the algae has not been confirmed. In case of proliferation, it is advisable not to collect shells. “The fish must be gutted before being consumed, the toxins accumulating in the digestive tract”, explains Nathalie Arnich, coordinator of the expertise.
