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Coral toxicity, specifically caused by palytoxin, is a serious condition resulting from exposure to certain species of soft corals, such as Zoanthid corals. Palytoxin is a potent toxin that can be absorbed through inhalation or skin contact, particularly during the cleaning or removal of corals from home or public aquariums. Symptoms of exposure can include respiratory distress, skin irritation, and, in severe cases, cardiovascular issues. Early recognition and management are crucial in preventing complications and improving outcomes for affected individuals. Participants in this course learn how to effectively identify, evaluate, and treat coral toxicity caused by palytoxin. The course emphasizes the importance of working collaboratively with an interprofessional team, including emergency care professionals, toxicologists, and dermatologists, to ensure accurate diagnosis and prompt treatment. This integrated approach enhances patient outcomes by enabling timely interventions and coordinated follow-up care. Objectives: Differentiate palytoxin toxicity from other causes of respiratory or dermatologic symptoms in patients with exposure to corals, particularly Zoanthid species. Identify the clinical signs and symptoms associated with palytoxin exposure, including respiratory distress, skin irritation, and cardiovascular complications. Screen for potential coral toxicity in patients presenting with unexplained symptoms following exposure to home or public aquariums. Explain the importance of improving care coordination amongst the interprofessional team to enhance the delivery of care for patients with coral toxicity. Access free multiple choice questions on this topic.

Corals are invertebrates that fall within the class Anthozoa of the phylum Cnidaria. They are mostly marine inhabitants and typically live in compact colonies of numerous polyps. They are one of the important reef builders in tropical oceans. Many corals, like Zoanthid corals, also known as soft corals, are a very popular component of aquariums (home or public) due to their beauty and low maintenance. Species of Zoanthid corals, such as Palythoa and Zoanthus, can contain a highly toxic, potentially lethal compound known as palytoxin. Coral toxicity, therefore, is palytoxin toxicity. Aquarium shop workers and home aquarium hobbyists may be at increased risk of exposure. So these corals have important implications for human health, but the associated health risks are often unrecognized or underestimated due to the limited number of documented cases. Palytoxin (PTX) is a polyhydroxylated and partially desaturated non-proteinaceous substance that is highly toxic. It is one of the largest naturally occurring polymeric products with a molecular weight of 2680 kilodaltons. Its lethal dose in mice, when administered intravenously, is 150 ng/kg body weight. PTX has also been found in certain fish,  phytoplanktons, and certain marine bacteria. Toxicity from sources other than corals has also been routinely reported. In recent years, the toxicological implications of PTX exposure from soft corals for human health have been increasing. The number of human poisonings, mostly in aquarium enthusiasts after the manipulation of PTX-contaminated soft corals, is continuously increasing; this is due mainly to the lack of sufficient control over the coral trade, and also to the underestimation and limited understanding of the entity.[1][2]

PTX exposure and resulting toxicity via coral are primarily associated with inhalation of vapors during cleaning, scrubbing, or removing coral from home/public aquariums. Due to their rapid growth, zoanthids require regular removal from specific unwanted areas of the aquarium. The removal process is mostly by boiling in water and/or by scrubbing off rocks. This process may result in inhalation of steam or aerosolized droplets. Also, instances of dermal absorption following prolonged, unprotected handling of PTX-containing coral have been reported. It can occur via both intact and broken skin. PTX toxicity can occur due to the consumption of seafood capable of producing PTX or seafood contaminated with corals. Also, reports of corneal toxicity have been reported caused by PTX.[1][3][4][5]

Zoanthids are common in the tropical and subtropical oceans, including the coastlines of Hawaii, Florida, Brazil, Australia, Japan, and many Atlantic islands. They usually live in the shallow, hard-bottom floors of the ocean up to 12 meters deep. However, zoanthids can be easily purchased online, so the toxicity can occur at any place. The majority of the cases of Coral toxicity are among aquarium enthusiasts. In recent times, an increasing number of cases of inhalational exposures have been reported among aquarium handlers during prolonged cleaning or handling of coral.[6]

Poisonings associated with PTX-contaminated soft corals are mostly through inhalation or dermal absorption. However, the ingestion of corals or surrounding seawater is less likely but not impossible. The exact in vivo mechanism of the toxicity of PTX is not established. PTX is a potent vasoconstrictor. The neurotoxic, cardiotoxic, and metabolic effects are mainly due to the dysregulation of sodium/potassium adenosine triphosphatase (ATPase), a transmembrane pump. PTX locks into the α-β ATPase heterodimer in the pump, leading to a sequence of conformational changes and thereby allowing passive transport of both ions (sodium and potassium), which in turn destroys the ion gradient, the very essence of cellular homeostasis. Therefore, PTX can affect any cell line depending upon the mode of exposure.[1][5][7][8][9]

There is increasing evidence of inhalational and/or cutaneous exposure to PTX after handling PTX-contaminated soft corals. Coral toxicity from palytoxin depends on the duration and route of exposure, and the distance from the location where the coral was handled. The patient may seek medical attention minutes to hours after maintaining a home aquarium. A detailed history of the patient's activity before the symptoms, as well as the patient's hobbies and occupation, would yield useful information. The patient usually describes an event involving handling corals, mostly by pouring boiling water over them and scrubbing the corals from the rocks. The resultant vapor exposure may present with symptoms. The most common presentations are: Respiratory system Rhinorrhoea Cough Dyspnea Musculoskeletal System Weakness Myalgia Muscle cramps Rhabdomyolysis Nervous System Paresthesia Convulsions Dizziness Numbness Restlessness Other systemic symptoms Fever Nausea/vomiting Tachycardia Hypotension Handling of corals with intact or damaged skin for a prolonged period may result in dermal absorption of the toxin and present with: Local (edema, erythema, pruritus) Perioral paresthesia Dysgeusia Other non-specific systemic symptoms. Instances of ocular contamination result in non-specific symptoms of keratoconjunctivitis. The symptoms also include severe ocular pain, red eye, decreased visual acuity, photophobia, foreign body sensation, and metallic taste. The patient may present with severe respiratory distress and cyanosis, which can result in progressive respiratory failure and death.[1][3][4][9][10][11][12][13]

The diagnosis of coral toxicity has no confirmatory study or imaging, as it is a clinical diagnosis based primarily on a clear history of prior exposure to PTX-containing coral species and the subsequent symptomatology. There is a wide variety of possible presentations; therefore, a strong history and clinical suspicion make the foundation for an accurate diagnosis. PTX has been successfully isolated using high-performance liquid chromatography in some public health cases. However, there is no qualitative or quantitative test used to assess human toxicity, and  PTX is not isolated for diagnosis in patients. Results from recent reports indicate a negative culture for an infectious cause and a temporal relationship to palytoxin exposure. The evaluation of the patient depends on the mode of exposure and clinical presentation. This assessment may include an electrocardiogram and respiratory monitoring.[4][10][12]

So far, no antidote has been developed against PTX toxicity. Additionally, there is no defined, harmonized medical protocol for treating PTX associated with corals. In general, the management is mainly symptomatic and focused on reducing or limiting the signs and symptoms of toxicity and limiting further damage. Hence, they are defined on a case-by-case basis. Following dermal or ocular exposure, rinsing the affected area with water can help reduce toxicity. Many approaches to inhalational PTX exposure have been studied. One approach focuses on the use of nebulized β-agonists and/or systemic corticosteroids. Another approach is based on the association of non-steroidal anti-inflammatory drugs with nebulized β-agonists, or on a combination of corticosteroids and antihistamines. For cutaneous exposure, treatment with supportive intravenous fluid infusion, corticosteroids, and antihistamines is mandatory. For ocular exposure and limited toxicity, artificial tears, steroid drops, and/or antibiotics are common choices. More serious damage to the eye, such as keratitis and ulcers, may require surgical exploration and management, including amniotic membrane transplantation. For patients arriving at the emergency department with dyspnea, cyanosis, and respiratory difficulties, progression to respiratory failure should be anticipated, and intensive care should be made available. Also, the toxic effects of PTX on the heart should receive proper attention, using an electrocardiogram. Animal studies using vasodilators such as papaverine and isosorbide dinitrate have shown that these can serve as antidotes. However, the animal experiments showed benefits only when these agents were injected directly into the heart immediately after exposure.[14][15][16]

The differential diagnosis of coral toxicity includes the following: Acute anemia Acute gastritis Aspiration syndromes Congenital anomalies of the lungs Hematologic problems Intestinal perforation Metabolic problems Portal hypertension Pulmonary air leaks Renal artery aneurysm Small intestinal diverticulosis Upper gastrointestinal bleeding

Patients with mild exposure and minimal symptoms may require symptomatic treatments and recover well. In cases of serious presentations, including respiratory failure, cardiotoxicity, keratoconjunctivitis, rhabdomyolysis, and kidney failure, there is a significant increase in morbidity and mortality.[14][15][16]

Coral toxicity due to PTX may have various effects and complications depending upon the mode and duration of exposure. Mild toxicities have local and non-specific systemic symptoms. More severe cases can result in hemolysis, cardiotoxicity and myocardial damage, severe respiratory distress, pulmonary edema, rhabdomyolysis, kidney failure, coma, and death resulting from cardiac or respiratory failure. Also, ocular exposure can be severe enough to result in corneal ulceration and even perforation.[14][15][16]

In recent years, there has been growing evidence of inhalational or cutaneous exposure to PTX toxicity associated with corals, mostly occurring after handling PTX-contaminated soft corals, eg, during the cleaning and maintenance of home/public marine aquaria. The high toxic potential of PTX identified in soft corals and the uncontrolled trade of these zoanthids have raised serious concerns for human health. In fact, with the growing number of documented cases of these poisonings, it can be considered an emerging sanitary problem. One way to stay safe while keeping an aquarium with any coral is to assume palytoxin is present. Thus, take appropriate precautions when handling corals to avoid exposure. Also, aquarium owners should be encouraged to minimize coral handling and to use protective wear, including gloves, masks (with activated charcoal filters), and glasses whenever handling corals. Avoid rough handling of corals, including excessive rubbing, scrubbing, and boiling, as these can produce aerosols and vapors. There have been proposals that the best approach to maintaining these zoanthid species in home aquaria is their removal by a trained professional. After removal and disposal, the aquarium water can be cleared of PTX (over 99%) using activated carbon treatment. Public health activists can help by focusing on educating the public about this emerging health problem. Also, legal oversight of coral buying and selling may increase awareness and help reduce future cases.[17][18]

Based on the available literature, most cases likely present to the emergency department within minutes to many days after exposure. Mostly, the management is supportive, but the range of patient presentations and complications may require collaboration among different healthcare professionals. The management of coral toxicity is with an interprofessional team consisting of emergency department clinicians, internists, a toxicologist, intensivists, surgeons, and nurses. Prompt evaluation is necessary to prevent delays in providing appropriate treatment, thereby significantly reducing morbidity and mortality associated with coral toxicity.