Sore throats, coughing, sneezing, shortness of breath, headache, eye irritation, rashes – people on Anna Maria Island with some of these symptoms are complaining they have the “red tide flu.”
There’s no such thing, according to Brad Dalton, deputy press secretary for the Florida Department of Health.
“To our knowledge there are no medical conditions referred to as the ‘red tide flu,’ ” he said.
But a growing body of scientific research proves that red tide has human health effects, and not just on people with respiratory problems.
Studies show that red tide affects healthy lifeguards, increases emergency room admissions, can have lasting effects on some people for days after they leave the beach, and affects people up to four miles inland. One study also indicates a possible antidote for red tide.
The culprit: Red tide toxin
The algae known as Karenia brevis, which began blooming in overabundance in the Gulf of Mexico and inland waters in Collier County last October, kills fish, marine mammals, sea turtles and shorebirds and makes shellfish unfit for consumption. It drifted north to Anna Maria Island on Aug. 3, and people have been suffering symptoms here ever since.
The symptoms are triggered by a neurotoxin, called brevetoxin, that is stirred up by wave action and winds. When it becomes airborne, particularly blowing towards land, it can cause watery eyes, tickly throats and coughing, especially in people with respiratory issues such as asthma, emphysema or COPD, said Tom Larkin, environmental health director for the Manatee County Health Department.
“The aerosolized product can cause asthma attacks to flare,” he said. “If you go to the beach and experience those symptoms, leave and go to another beach, because it can be at one beach and not another. If you live here, stay inside air conditioning and limit your outside exposure,” he said, adding that an “N-95” mask, available at hardware stores, can help filter out red tide.
Studies confirm that using a surgical mask decreases inhalation of brevetoxin by up to 45 percent.
But inhaling the brevetoxin is not the only way you can be exposed to red tide, according to the Centers for Disease Control (CDC).
Symptoms can follow ingesting red tide water by swallowing or even by breathing in tiny water particles in the air, eating contaminated shellfish or through skin contact while swimming or wading.
“Marine Harmful Algal Blooms (HABs) can cause a variety of illnesses in people,” both immediate and recurring, according to the CDC.
Red tide antidote
A promising recent development is a study on sheep that has identified brevenal, an antidote to brevetoxin, in Karenia brevis itself. Experiments showed that brevenal helps clear the lungs of mucus produced by inhaling red tide. Researchers noted in “Pathophysiologic Airway Responses to Inhaled Red Tide Brevetoxin in Allergic Sheep” that it is the first documented case of a toxin-producing organism also producing its own antidote.
Red tide affects people inland
A study, “Inland Transport of Aerosolized Florida Red Tide Toxins,” shows that red tide can travel four miles inland from a red tide-affected beach. In addition, “People may still be exposed environmentally to the aerosolized brevetoxins even after they leave the beach,” according to the study. “Indeed, if people remain on a barrier island where no point is greater than 1.6 km (about 1 mile) from a coast, they will most likely be continuing their exposure in any outdoor setting and from all directions if the inland waters also contain K. brevis blooms.”
Inland waters including the Manatee River, Palma Sola Bay and Sarasota Bay all have shown evidence of red tide this month.
“Currently, the public health message in communities with onshore Karenia blooms has only recommended leaving the beach area to avoid aerosol exposure; this message needs to be re-evaluated based on these new findings to take into account the possibility of inland environmental exposure to brevetoxins, particularly for persons with underlying lung diseases such as asthma,” the study concluded.
Red tide worse for people with asthma
People with asthma experience “objectively measurable adverse changes in lung function from exposure to aerosolized Florida red tide toxins,” particularly among those requiring regular therapy with asthma medications, according to the study, “Aerosolized Red-Tide Toxins (Brevetoxins) and Asthma.”
The study “Florida Red Tide Toxins (Brevetoxins) and Longitudinal Respiratory Effects in Asthmatics” found that only one hour of exposure to Florida red tide aerosols can cause increased symptoms and decreased respiratory function lasting for at least several days after exposure.
“We recommend persons with underlying respiratory disease (and their healthcare providers, emergency medical facilities and public health officials) be aware of the onshore activity of Florida red tide blooms, and avoid visiting coastal areas with strong onshore winds during onshore blooms. This appears to be particularly important for poorly controlled asthmatics, and those with relatively little regular brevetoxin exposure (for example, those who live inland or visitors).”
ER visits up during red tide
Emergency room admissions for respiratory problems increases with red tide, according to a study called “Environmental Exposures to Florida Ted Tides,” which noted “a significant increase in the rates of respiratory disease admissions to an ER for coastal residents during a year when there was a red tide bloom over several months compared to respiratory disease admissions during no red tide.”
Red tide affects healthy people
Studies show that red tide also affects people without underlying respiratory problems.
In one study, “Occupational Exposure to Aerosolized Brevetoxins during Florida Red Tide Events: Effects on a Healthy Worker Population,” 28 healthy Florida lifeguards exposed to red tide toxins at work reported airway irritation including eye irritation, nasal congestion, cough and headaches.
Island lifeguards are coping with red tide with masks and air-conditioned lifeguard stands, Manatee County Marine Rescue Chief Joe Westerman said. The beach flag system does not specifically address red tide, but if it is bad enough that swimming is not advisable, beaches will be closed with a double red flag, as they have been a few days this month, he said.