Red tide along Galveston coast: What beachgoers need to know

Clinicians at The University of Texas Medical Branch (UTMB Health) are warning that a red tide bloom affecting the Gulf Coast could cause respiratory symptoms in beachgoers and pose additional risks for people with asthma and other chronic lung conditions.

How red tide affects your health

The bloom is caused by Karenia brevis, a microscopic marine organism that produces toxins called brevetoxins. When wind and waves send tiny droplets containing the toxin into the air, people near the beach can inhale them and develop coughing, sneezing, a runny nose, throat irritation, burning or watery eyes, and shortness of breath. Symptoms often begin while a person is at or near the beach and improve after leaving the area.

"People don't have to go into the water to be affected by red tide," said Dr. Julia W. Tripple, an associate professor in the Department of Internal Medicine specializing in Allergy and Immunology at UTMB. "The toxins can become airborne in sea spray, so simply spending time on the beach can cause coughing, eye and throat irritation, or other respiratory symptoms. People with asthma or chronic lung disease should be especially cautious and consider avoiding affected beaches while a bloom is present."

People with asthma or chronic obstructive pulmonary disease, or COPD, may experience worsening symptoms and decreased lung function even after relatively brief exposure. Older adults and people with a history of migraines also may be more sensitive to the effects of a bloom.

What to do if symptoms develop

People who develop mild respiratory or eye irritation should leave the beach. Moving indoors to air-conditioned air often helps respiratory symptoms, while rinsing the eyes and skin with fresh water may relieve irritation. Anyone experiencing wheezing, significant difficulty breathing or symptoms that do not improve after leaving the area should seek medical care.

People with asthma or other chronic lung conditions should continue taking their medications as directed and keep rescue inhalers readily available.

According to the National Oceanic and Atmospheric Administration (NOAA) Harmful Algae Bloom forecast issued on Friday, Sept. 18, some beaches in Galveston may experience a moderate risk of respiratory irritation from red tide over the next 36 hours.

Red tide also presents a different health risk through contaminated shellfish. Oysters, clams, mussels, and other molluscan shellfish can accumulate brevetoxins from the water. Eating contaminated shellfish can cause neurotoxic shellfish poisoning.

Symptoms typically begin within a few hours of eating contaminated shellfish and can include nausea, vomiting, diarrhea, and abdominal pain, along with neurological symptoms such as tingling or numbness around the mouth or in the arms and legs, dizziness, problems with coordination, and slurred speech.Some people experience "temperature reversal," in which hot objects feel cold and cold objects feel hot.

Severe cases can cause muscle weakness, partial paralysis or breathing problems. Cooking contaminated shellfish does not destroy the toxin.

People should not harvest or eat shellfish from waters affected by a red tide bloom or from areas that are not monitored for safety. Commercially available shellfish from regulated sources are subject to harvesting restrictions and testing designed to keep contaminated products out of restaurants and markets.

Anyone who develops gastrointestinal and neurological symptoms after eating shellfish should seek prompt medical attention. There is no specific antidote for neurotoxic shellfish poisoning, but treatment can help control symptoms and prevent complications.

Before heading to the beach

Because red tide conditions can change with winds, currents and the location and concentration of the bloom, beachgoers should check current conditions and local advisories before heading to the coast.

During an active bloom:

• Consider avoiding affected beaches, particularly when winds are blowing from the Gulf toward shore.
• People with asthma, COPD or other chronic lung conditions should avoid affected areas and keep prescribed medications available.
• Leave the beach if coughing, throat or eye irritation, shortness of breath or other symptoms develop.
• Do not harvest shellfish from affected or unmonitored waters.
• Seek medical attention for significant breathing difficulty or for gastrointestinal symptoms accompanied by neurological symptoms after eating shellfish.

Red tide is a naturally occurring phenomenon, but the toxins produced during a bloom can affect people as well as marine life. Paying attention to current conditions and limiting exposure when blooms are present can help reduce the risk of illness.