Zoanthid corals are commonly kept in home aquariums. They produce a potent palytoxin that has various neurologic effects, including paresthesia, weakness, and respiratory depression. We report on the case of a previously healthy male who handled a zoanthid coral in his aquarium and had subsequent bilateral lower extremity weakness. His symptoms resolved after supportive treatment of oral potassium replacement and intravenous fluids.

The Case

A previously healthy 34-year-old male presented to the emergency department with bilateral lower extremity weakness. He was able to walk when he woke up that morning but then was unable to stand without support. The day before presentation, the patient was moving a zoanthid coral with his bare hands. He denied any injury from the coral, but he had superficial lacerations on his hands from yard work. He denied tick exposure, camping, pets, recent travel, fever, illness, previous medical history, and personal/family history of neuromuscular or rheumatologic disorders. His physical exam showed inability to flex his bilateral quadriceps, with 4/5 strength on plantar and dorsiflexion of ankles and knees. He had equal sensation bilaterally, including the anterior thighs. There were no obvious injuries. CT of the brain and cervical spine were negative. Labs showed a potassium of 2.7. He was admitted to the hospital following a negative MRI. He received oral potassium and intravenous fluids with resolution of his weakness. Neurology suspected hypokalemic periodic paralysis (HPP). The patient was discharged with neurology follow-up.

Discussion

Zoanthid corals are often kept in home aquariums and produce a deadly vasoconstrictor called palytoxin. The toxin binds Na+/K+ ATPase and destroys the ion gradient across cell membranes, leading to cell death. Doses as low as 0.033 mcg/kg can be lethal. Case reports and anecdotal forums show that most exposures come from inhalation or skin contact. There are currently no guidelines for proper protective gear for handling these corals. There is no known antidote, and treatment is supportive.¹

A 2015 Morbidity and Mortality Weekly Report from the Centers for Disease Control and Prevention shows that palytoxin exposure may cause nausea, headache, renal failure, weakness, ataxia, fever, and other symptoms.² These cases were seen in Alaskan aquarium shops and homes after individuals handled the coral without protective gear. Multiple aquarium store employees, along with all the residents of a home who were exposed to the coral, developed symptoms that mostly resolved by the following morning.

“Doses as low as 0.033 mcg/kg can be lethal. Case reports and anecdotal forums show that most exposures come from inhalation or skin contact. There are currently no guidelines for proper protective gear for handling these corals. There is no known antidote and treatment is supportive.”

There are various other case reports of palytoxin exposure. One case was that of a 25-year-old female who handled a zoanthid coral from her home aquarium and subsequently developed perioral paresthesia and dysgeusia (alteration of the sense of taste) that lasted for several days. She was treated with corticosteroids and antihistamines.³ Another case involved a patient who experienced dizziness, generalized weakness, myalgias, electrocardiogram abnormalities, and rhabdomyolysis. The symptoms resolved after supportive treatment with intravenous fluid.⁴