The toxic algae bloom known as Red Tide has left a trail of dead fish in its wake up the western coast of Florida. The bloom that had been wreaking havoc on our southern neighbors has now made its way to the Tampa Bay area. High concentrations of the algae have been found in water samples at several local beaches, and beachgoers are seeing and smelling the effects. Many allergy and asthma sufferers have been feeling symptoms for weeks.
Red Tide is a marine algae known as Karenia brevis that produces toxins that can be harmful to sea life and humans. Algae are vital to our ocean ecosystem, but under certain environmental conditions they thrive, feeding on a variety of pollutants like phosphorus and nitrogen from fertilizer as well as runoff and wastewater. In this environment, K. brevis can grow quickly, forming large blooms that create a reddish-brown color in the ocean. This creates the phenomenon we know as Red Tide.
K. brevis releases a toxin called brevetoxin that can cause problems when ingested or inhaled. This toxin kills large amounts of fish and negatively affects our shorelines. During Red Tide season it is wise to be cautious when ingesting shellfish but important to know that the state of Florida closely monitors shellfish beds in Red Tide areas and closes them until shellfish are safe to eat again. The brevetoxins tend to accumulate in shellfish and, when ingested, can cause neurotoxic shellfish poisoning, which is marked by gastrointestinal symptoms as well as neurologic ones like tingling in fingers and toes.
Toxins can aerosolize in the wind that drifts ashore and trigger or worsen upper and lower respiratory problems. There is much evidence of upper and lower respiratory tract irritation upon exposure. In my experience, patients who suffer with asthma or allergies are more likely to experience symptoms with Red Tide exposure. These patients experience itching and burning of eyes, irritation of throat and nasal symptoms like congestion, sneezing and itching. Coughing, wheezing and chest tightness have also been reported. Asthmatics may develop exacerbations of previously stable asthma requiring more intensive treatment. Many patients also report skin irritation like stinging, burning or a rash when coming in contact with the seawater.
Swimming in the water during Red Tide can also cause ocular and skin symptoms. If you experience skin or eye irritation, rinse off with freshwater.
If you have known allergies or asthma, it’s best to avoid the beach during a Red Tide outbreak. If you have asthma and do decide to visit the beach, bring your rescue inhaler.
With our changing climate it seems Red Tide blooms are becoming an annual occurrence. Until we find ways to reduce their occurrence, people with pre-existing upper and lower respiratory conditions like allergic rhinitis, asthma and COPD should be cautious. You can check the conditions at local beaches at Mote Marine Laboratory & Aquarium’s website (visitbeaches.org).
Dr. Mona V. Mangat is a board-certified allergist and immunologist at Bay Area Allergy & Asthma in St. Petersburg. Find her at bayallergy.com. Contact her at firstname.lastname@example.org.