On August 12, 2014, an Anchorage hospital notified the Alaska Section of Epidemiology
(SOE) that a middle-aged male resident of Anchorage (patient A) had arrived in the
emergency department with possible palytoxin exposure. Patient A complained of a bitter
metallic taste, fever, weakness, cough, and muscle pain 7–8 hours after introduction
of live zoanthid coral into his home aquarium. Palytoxin, a potent toxin known to
produce the reported effects, is contained in zoanthid marine corals (1,2).
This call prompted SOE to launch an epidemiologic investigation, during which investigators
interviewed exposed persons, obtained environmental specimens for testing, and provided
advice about avoiding continued exposure. Patient A reported that two persons (patients
B and C) who lived with him experienced similar symptoms around the same time. Patient
A also reported that the owner of a local aquarium shop knew of numerous reported
aquarium-related poisonings associated with suspected palytoxin-containing zoanthids,
both through personal experience and through online marine aquarium forums (3). Patient
A reported that the shop’s owner believed that he and several of his employees and
customers had been previously exposed, some multiple times.
A specimen obtained from patient A’s introduced coral, as well as a specimen obtained
from the shop, were both positive for palytoxin. An extended investigation identified
seven additional Anchorage residents who appeared to have experienced acute palytoxin-related
illness during the preceding 2 years. Many aquarium store employees and marine aquarium
hobbyists are not aware of palytoxin as a potentially serious hazard associated with
handling some zoanthid corals sold in aquarium stores or exchanged by hobbyists. Persons
who are likely to handle such organisms should be made aware of the potential health
risks so that they understand how to prevent exposure to this potent toxin.
Case Reports
On August 11, 2014, at 10:30 p.m., a relative of patient A transferred 70 pounds (32
kg) of live coral from a plastic container into patient A’s 200-gallon (758-L) aquarium
in his 1,600-square-foot (149 square-meter) mobile home. During the transfer, several
coral fragments fell to the floor, causing some of the live polyps to break off. Patients
B and C were asleep in an adjacent room <20 feet [<6 m] from the aquarium while the
coral was being transferred. Patient A arrived home at 11:30 p.m. and slept for approximately
7 hours in the room with the aquarium. On August 12, at approximately 7:00 a.m., patients
A, B, and C awoke with neurologic, respiratory, musculoskeletal, and other symptoms
(Table). Because of the severity of patient A’s symptoms, which included cough, nausea,
headache, and muscle and joint pain, he was taken to a nearby hospital emergency department,
where he was tachycardic, tachypneic, and febrile (maximum temperature = 103°F [39.4°C]).
His white blood cell count was elevated at 13,800 cells/cubic milliliter with 86%
neutrophils. His renal function tests, urinalysis, troponin I, creatinine kinase,
and chest radiograph were unremarkable. Influenza A and B tests were negative. He
was admitted to the hospital for supportive care. Patients B and C gradually improved
throughout the day and their symptoms completely resolved by 7:00 p.m. Patient A was
released 2 days later, after resolution of his symptoms. The person who introduced
the coral into the aquarium was reported to be asymptomatic.
Patient A stated that the household dog had vomited the morning after coral introduction
(August 12) and both the dog and the household cat appeared to be lethargic that day.
Patients A and C noted a visible mist and sensed humidity in the mobile home on the
morning after coral introduction, leading them to suspect a possible problem with
the aquarium. The patients reported learning that palytoxin was a possible cause of
their illness from the owner of the shop. The shop owner stated that he had experienced
similar symptoms on multiple occasions after handling zoanthid corals, and that he
had read numerous similar reports posted by other marine aquarium enthusiasts through
online blogs (3). SOE advised patients A, B, and C to decontaminate surfaces near
the aquarium with dilute household bleach while wearing personal protective equipment
including face mask, goggles, and overalls.
Laboratory Analysis
SOE arranged with the U.S. Food and Drug Administration Center for Food Safety and
Applied Nutrition to test coral samples from the shop and from the aquarium in patient
A’s house. Three samples from the shop and two samples from the home of patient A
were selected on the basis of visual resemblance to zoanthids previously reported
to contain palytoxin (2). Quantitative analysis was performed using high performance
liquid chromatography with ultraviolet detection compared against a palytoxin standard
(2). The analysis confirmed 7.3 mg crude palytoxin/g wet weight of zoanthid tissue
in one coral sample from patient A’s home aquarium (Figure) and 6.2 mg crude palytoxin/g
wet weight zoanthid in one coral sample from the shop. The three additional coral
samples were nontoxic or only weakly toxic. The levels of palytoxin in the corals
exceeded those found in investigations of previous similar poisoning events (0.5 mg/g–3.5
mg/g) (2). An additional analysis by high resolution liquid chromatography mass spectrometry
(2) confirmed that the primary toxin in both samples was palytoxin (molecular weight
= 2,680 kilodaltons). Genetic analysis (2) determined that both toxin-containing zoanthid
samples were consistent with previous molecular identifications of a highly toxic
variety of Palythoa species collected from multiple aquarium shops in Maryland and
Virginia, and from three similar aquarium-related poisoning events in New York, Ohio,
and Virginia. Both specimens were genetically and visually distinct from the nontoxic
or weakly toxic specimens from this case and similar previous cases.
Additional Case Reports
SOE followed up with the owner of the shop to identify additional cases. He reported
that he and several aquarium shop staff members had experienced numerous episodes
of likely palytoxin poisoning resulting in acute onset of clinically compatible symptoms
(Table). The most recent recalled incident occurred in July 2014, and involved seven
staff members who were exposed either while dismantling a customer’s private aquarium
containing corals or upon later handling of the aquarium contents at the shop. SOE
interviewed four of the staff and the shop owner (patients D, E, F, G, and H). All
reported experiencing a bitter metallic or salty taste within 2 hours of exposure,
followed by one or more of the following: cough, joint pain, flank pain, fever, and
cold sensation during the night. Signs and symptoms largely resolved by the following
morning (Table). Possible palytoxin exposure occurred while mouth-siphoning water
out of the aquarium, and transporting and handling coral rocks that were exposed to
air. Two staff members reported experiencing similar symptoms several weeks after
the July 2014 event, after handling the same corals out of water and after cleaning
dry plastic pipes from the aquarium with hot water.
Several staff members reported symptoms consistent with palytoxin exposure on multiple
occasions; one had experienced such symptoms nine times. SOE was able to interview
only five shop staff members; however, at least three others were reportedly exposed
to palytoxin. Subjects reported managing their symptoms by increasing intake of fluids.
SOE provided information to shop staff on how to detoxify palytoxin on surfaces using
diluted household bleach.
The owner of the shop notified SOE of two additional suspected palytoxin poisonings
in an Anchorage household in 2012. These two persons (patients I and J) reported fever,
tremors, weakness, ataxia, and other symptoms (Table) within hours of cleaning a fish
tank that contained zoanthids. Both patients were hospitalized in the intensive care
unit for several days. Patient I, who was pregnant at the time, experienced preterm
labor the day after her hospital admission and delivered her baby at 6 months’ gestational
age. The child survived and reportedly suffered no apparent long-term adverse health
effects. Patient J reported lingering pulmonary effects 2 years after exposure. Palytoxin
exposure likely occurred after patient J cut polyps away from their rock base under
hot water in the home garage; his wife (patient I) and dog walked through the garage
several times during the process. The dog reportedly vomited and was lethargic following
the tank cleaning.
Summary
What is already known on this topic?
Palytoxin is a potentially life-threatening toxin that can act via dermal, inhalation,
and oral routes of exposure. Marine aquarium hobbyists who introduce certain zoanthid
corals into their aquariums are at risk for palytoxin exposure.
What is added by this report?
At least ten persons in Alaska developed signs and symptoms compatible with palytoxin
exposure after either handling zoanthid corals or being in proximity to someone who
did.
What are the implications for public health practice?
The risks for palytoxin exposure are unknown to many in the commercial aquarium and
hobbyist communities. Activities that could potentially produce aerosols (e.g., scrubbing
or using hot water to remove zoanthids) should be undertaken with caution. Hobbyist
and commercial coral growers and the public health and health care provider communities
might benefit from common recommendations on coral handling and decontamination practices
from state and federal public health agencies. Illnesses after a potential exposure
should be promptly reported to the state or local health department.
Discussion
Palytoxin is a potent vasoconstrictor that acts by binding to Na+/K+ ATPase, which
leads to destruction of the ion gradient across cell membranes, passive transport
of ions, and ultimately, cell death (4). It causes a range of effects in animals and
humans, depending on the route of exposure (5,6). The dose at which 50% of exposed
animals die following intravenous administration of palytoxin (LD50) has been shown
to be as low as 0.033 μg/kg body weight (6). Higher concentrations are required to
cause effects following incidental contact depending on whether the exposure occurs
through dermal, inhalation, or oral routes (5). Based on reports in the medical literature
(7) and online forums (3), most aquarium-related exposures occur after subjecting
zoanthids to prolonged handling and appear to be related to inhalation or to skin
exposures through cuts on the hands and fingers in persons who maintain these types
of aquariums. Throughout the Mediterranean region, palytoxin exposure has been linked
to fever, conjunctivitis, and respiratory symptoms in persons exposed to marine aerosols
during proliferations of palytoxin and palytoxin-like compound–producing marine algae
(i.e., algal blooms) (5), but detailed inhalation studies in animal models are lacking.
No antidote is available for palytoxin; treatment is supportive.
Zoanthids (Class Anthozoa, Subclass Hexacorallia, Order Zoanthidia [colonial anemones])
are common in home aquariums. They are considered relatively easy to keep and are
often recommended to new aquarium owners. Some types of colonial anemones form large
aggregations encrusting a hard substrate. In an aquarium, these aggregations often
require thinning or removal. Because of the way these organisms attach to surfaces,
aggressive methods are sometimes required for their removal, including cutting, scraping,
applying chemicals, or scalding with hot water, which lead to an increased potential
for palytoxin exposure, often through the presumed production of aerosols (7). Other
potential exposure routes include direct contact with eyes, through skin lesions,
and incidental ingestion. Although not all zoanthids contain palytoxin, some zoanthids
commonly found in home aquariums contain high concentrations of this toxin (2). Some
coral enthusiasts appear to be able to maintain them without ill effects, likely through
proper handling, aquarium management, and decontamination practices. Palytoxin can
be neutralized by soaking the coral for 30 minutes in a ≥0.1% household bleach solution
(1 part 5%–6% sodium hypochlorite [household bleach] to 10 parts water, prepared fresh)
(8). Contaminated items should be soaked in diluted bleach before disposal (3).
Palytoxin is known to some coral hobbyists (3), and the Anchorage aquarium shop displayed
many signs warning that some coral might be very toxic. However, no U.S. regulations
govern the testing or labeling of coral that might contain toxins, including palytoxin.
Regulations for the importation of corals currently enforced by the U.S. Fish and
Wildlife Service pertain to endangered species and reflect ecological concerns (9).
General recommendations on coral handling and decontamination practices would be helpful
for hobbyists, commercial coral growers, and the public health and clinical provider
communities.
Currently, no official evidence-based recommendations exist for proper personal protective
equipment use for coral hobbyists and aquarium shop staff, and development of such
recommendations might be helpful. Activities that could potentially produce aerosols
(e.g., scrubbing or using hot water to remove zoanthids) should be undertaken with
caution. Patients A, B, and C did not handle any of the corals directly; rather, they
were present in the home shortly after the introduction of palytoxin-containing zoanthids
to the aquarium. Until data from controlled inhalation experiments in an animal model
are available, this apparent link between palytoxin and inhalation toxicity will remain
associative and evidence-based recommendations on appropriate respiratory protection
or handling best practices will not be possible.