142 Marine Food-Borne
Poisoning, Envenomation,
and Traumatic Injuries
Stephen Thornton and Richard F. Clark
KEY POINTS
• Scombroid is thought to be caused by breakdown of
histidine into histamine in dark-meat marine fish and
can be managed with antihistamines.
• Ciguatera poisoning results from the consumption of
large tropical predatory reef fish that have
bioaccumulated ciguatoxin; it causes gastrointestinal
distress and neurologic symptoms.
• Tetrodotoxin blocks sodium channels and can lead to
ascending paralysis and respiratory failure.
• Box jellyfish (Cubozoa). Portuguese man-of-war
(Hydrozoa), and other stinging marine invertebrates
envenomate humans via nematocysts that contain a
stinging barb and venom.
• The box jellyfish (Chironex fleckeri) and related species
cause the most morbidity and mortality of all marine
envenomations.
• Acetic acid immersion is recommended for the
treatment of box jellyfish envenomation but may worsen
man-o-war envenomation.
• Hot water immersion appears to be an effective
treatment of almost all marine envenomations.
• Sea snake venom is neurotoxic and myotoxic.
Treatment with antivenom is effective.
• Evaluation for a retained foreign body should be
considered with stingray and spiny fish envenomation.
• Wound infection is a common complication of spiny
fish and stingray envenomation, and prophylactic
antibiotics effective against common pathogens such
as Vibrio species should be considered.
• Direct marine injuries are usually abrasions and
contusions, but fatal attacks by sharks and large
predatory fish do occur.
stinging organisms in the ocean cause significant morbidity.
Less common but more dramatic, attacks by sharks and other
large marine organisms cause deaths every year. Thus, it is
important for physicians to be aware of the hazards posed by
marine organisms and be familiar with appropriate treatment
options.
EPIDEMIOLOGY
Poisoning from the ingestion of marine animals such as shellfish and fish constitutes a small but consistent source of food
poisoning outbreaks and illnesses.1 Although mortality is low,
morbidity can be significant, with many patients needing to
seek medical care.2 Tetrodotoxin poisoning is an exception,
and significant mortality has been reported.3
Even though the vast majority of marine sea life is harmless
to humans, a small but important percentage does cause
human envenomation with resulting morbidity and mortality.
It is difficult to quantify the annual number of marine envenomations because most victims will not seek medical care and
reporting cases to health departments or poison centers is not
mandatory. Some estimate the number of marine envenomations worldwide to be greater than 10 million per year, with
the majority being caused by jellyfish.4 Deaths are reported
every year from envenomation by certain species of jellyfish,
most commonly the box jellyfish.5
The true number of traumatic injuries caused by marine life
is difficult to estimate. Most will consist of only minor abrasions and contusions, but occasional fatal traumatic injuries
do occur. Attacks by sharks and large predatory fish cause
human fatalities every year.6 Stingray barbs can cause significant direct trauma and death.7
MARINE FOOD-BORNE POISONINGS
PATHOPHYSIOLOGY
PERSPECTIVE
As human contact with the ocean and the organisms that live
in it continues to increase, the impact of poisonings, envenomations, and direct trauma by these marine organisms
will also grow. Marine food-borne poisonings can cause large
outbreaks, and direct envenomation by the innumerable
1216
The toxins responsible for the signs and symptoms of marine
food-borne illnesses are primarily produced in microorganisms such as dinoflagellates, diatoms, and marine bacteria
and are bioaccumulated by shellfish or fish, which are then
ingested by humans and result in toxicity. Most of these toxins
modulate neuronal and muscle sodium channels. Scombroid
is not caused by a preformed toxin but rather by breakdown
CHAPTER 142
Marine Food-Borne Poisoning, Envenomation, and Traumatic Injuries
Table 142.1 Common Marine Food-Borne Poisonings
TYPE OF
POISONING
TOXIN AND
MECHANISM OF ACTION
SOURCE OF
POISONING
TIME TO ONSET AND
COMMON SYMPTOMS
Scombroid
Histamine–histamine
receptor agonist
Large, poorly
refrigerated fish
Minutes
Flushing, pruritus urticaria
GI upset
Supportive
Antihistamines
Ciguatera
Ciguatoxin (from
Gambierdiscus toxicus)—
opens sodium channels
Large predatory
reef fish
Hours
Cold allodynia
GI upset
Paresthesias
Supportive
Paralytic
shellfish
poisoning
Saxitoxin (from
Protogonyaulax sp.)—
blocks sodium channels
Mussels, clams,
oysters
Minutes
Weakness
Paresthesias
GI upset
Rarely respiratory failure
Supportive
Respiratory
support in
severe cases
Neurotoxic
shellfish
poisoning
Brevetoxin (from
Ptychodiscus brevis)—
opens sodium channels
Mussels, clams,
oysters
Minutes to hours
GI upset
Cold allodynia
Paresthesias
Supportive
Amnestic
shellfish
poisoning
Domoic acid (from
Pseudonitzschia spp.)—
activates glutamate
receptors
Mussels
Minutes to hours
GI upset
Memory loss
Paresthesias
Seizures
Encephalopathy
Supportive
Tetrodotoxin
poisoning
Tetrodotoxin (from marine
bacteria species)—blocks
sodium channels
Puffer fish,
blue-ringed
octopus, newt
and frog species,
horseshoe crabs
Minutes
Paresthesias
Muscle weakness
GI upset
Ataxia
Paralysis
Respiratory failure
Supportive
Respiratory
support
TREATMENT
GI, Gastrointestinal.
of histidine into histamine in inadequately stored dark-meat
fish. Table 142.1 lists the common marine food-borne
poisonings, causative toxins, and typical sources of such
poisonings.8
food-borne poisoning would also need to be considered. The
diagnosis of marine food-borne poisoning must be made on
a clinical basis because testing for the specific toxins is not
readily available.
PRESENTING SIGNS AND SYMPTOMS
TREATMENT
Table 142.1 lists the typical onset and common symptoms
associated with marine food-borne poisonings. Typically, a
history of seafood ingestion can be obtained. In most cases
the symptoms are manifested within minutes to hours and
include a mixture of gastroenteritis (nausea, vomiting, and
diarrhea) and often dramatic neurologic findings.
Treatment of marine food-borne poisoning is entirely supportive (see Table 142.1). Attention should be paid to fluid
resuscitation and control of nausea and vomiting with antiemetics (ondansetron, 4 to 8 mg intravenously as needed).
Although scombroid can be treated with antihistamine therapy,
no antidotes are available for any other seafood toxin–
mediated poisonings.
DIFFERENTIAL DIAGNOSIS AND MEDICAL
DECISION MAKING
The differential diagnosis for marine food-borne poisoning
includes disease processes that cause acute neurologic symptoms with or without gastrointestinal symptoms. Botulism,
myasthenia gravis, poliomyelitis, and tick paralysis should be
considered. In cases in which the neurologic symptoms are
not as obvious, the more common bacterial causes of
MARINE ENVENOMATION
PATHOPHYSIOLOGY
Envenomation can occur from both marine invertebrates and
vertebrates. Members of the Cnidaria phylum, which includes
the box jellyfish, true jellyfish, Portuguese man-o-war, and sea
1217
SECTION XIV
BITES, STINGS, AND INJURIES FROM ANIMALS
severe hypertension, and it has caused deaths.12 The blueringed octopus has tetrodotoxin in its venom, which can cause
paralysis and respiratory failure.13 The cone snail’s venom is
a complex mixture of peptides that can lead to rapid paralysis
and death.14 Stonefish envenomation can result in cardiovascular instability and death, although severe local effects are
more common.10 Sea snake venom has both a neurotoxic
component, which leads to ascending paralysis, and a myotoxic component, which causes muscle breakdown.15 Table
142.2 summarizes the signs and symptoms of the more significant marine envenomations.
DIFFERENTIAL DIAGNOSIS AND MEDICAL
DECISION MAKING
Fig. 142.1 Lionfish—a member of the Scorpaenidae family of
fish.
Frequently, the identity of the offending marine organism will
not be known. The geographic location can be a useful predictor, and physicians should be aware of the venomous marine
organisms in their local area. It can be helpful to look for
physical clues, such as retained jellyfish tentacles and puncture marks. The presence of severe local pain often indicates
a Cnidaria or fish envenomation, whereas significant neurologic symptoms, such as weakness, should raise suspicion for
cone snail or other neurotoxic organisms.
TREATMENT
Fig. 142.2 Skin lesions after envenomation by jellyfish species.
anemone, have nematocysts with hollow venomous barbs that
deliver venom hypodermically. Stingrays have a serrated
spine connected to a venom gland located on the tail that can
be impaled into unsuspecting victims, whereas the Scorpaenidae family of fish (stonefish, lionfish, scorpion fish) have
venomous spines on their fins (Fig. 142.1). Table 142.2 lists
the most medically important offending marine organisms and
their toxicity.5,9-15
PRESENTING SIGNS AND SYMPTOMS
The signs and symptoms of marine envenomation depend on
the offending organism. Local pain and irritation are the most
common symptoms, especially when nematocysts and spines
are involved (Fig. 142.2). However, certain marine organisms
can cause severe systemic symptoms and even death. The
Australian box jellyfish (Chironex fleckeri) can cause sudden
cardiopulmonary collapse.5 The Irukandji jellyfish (Carukia
barnesi) can cause Irukandji syndrome, a condition characterized by severe whole-body pain and spasms, tachycardia, and
1218
Treatment of marine envenomation begins with addressing the
patient’s airway, breathing, and circulation status. Typically,
good supportive care and pain control are all that is needed.
Hot water immersion is recommended to control the pain
caused by Cnidaria, Scorpaenidae fish, and stingray envenomation and is efficacious because of the heat-labile properties
of the neurotoxic component of the venom responsible for the
pain. This is typically achieved by immersing the affected
body part in water heated to approximately 42° C to 45° C
for 20 minutes.16,17 Acetic acid may have a role in inactivating
the nematocysts of the box jellyfish and Irukandji jellyfish but
should not be used on other types of jellyfish because it may
worsen these envenomations.18 Recently, topical lidocaine was
shown to help in alleviating the pain and inactivating nematocysts from several different species of Cnidaria, including
the Portuguese man-o-war.19 Antivenom therapy is available
to treat poisoning by the Australian box jellyfish, the stonefish,
and the sea snake.20 Evaluation for a retained foreign body
should also be considered, especially with stingray and sea
urchin envenomation21,22 (Fig. 142.3). Table 142.2 summarizes the recommended treatments.
MARINE TRAUMATIC INJURIES
PATHOPHYSIOLOGY
Traumatic marine injuries are most often caused by the simple
action of scraping against the rock-hard and sometimes razorsharp exoskeletons of sponges, corals, and other sessile
marine organisms. Bites from sharks and fish cause trauma
directly related to the size of the animal, force of the bite, and
CHAPTER 142
Marine Food-Borne Poisoning, Envenomation, and Traumatic Injuries
Table 142.2 Signs and Symptoms of Significant Marine Envenomations
MARINE ORGANISM
METHOD OF
VENOM DELIVERY
CLINICAL FINDINGS
TREATMENT
Australian box jellyfish
(Chironex fleckeri)
Nematocysts
Linear rash, severe local and generalized
pain, muscle spasms
Rare: rapid cardiopulmonary collapse,
death
Supportive care
Pain management
Hot water immersion
Acetic acid irrigation
Antivenom
Irukandji jellyfish
(Carukia barnesi)
Nematocysts
Irukandji syndrome: tachycardia,
tachypnea, hypertension to
hypotension, whole-body muscle
spasms, pain
Rare: death
Supportive care
Pain management
Hot water immersion
Acetic acid irrigation
Vasodilators
Sea nettle (Chyrsaora
quinquecirrha)
Nematocysts
Local pain and irritation
Supportive care
Pain management
Hot water immersion
Lidocaine spray
Portuguese man-o-war
(Physalia physalis)
Nematocysts
Severe local pain, bullae, necrosis
Rare: hemolysis, shock, death
Supportive care
Pain management
Hot water immersion
Lidocaine spray
Do not use acetic acid
Thimble jelly (Linuche
unguiculata)
Nematocysts
Sea bather’s eruption: pruritic popular
eruption on the skin covered by a
bathing suit
Supportive care
Hot water immersion
Pain management
Fire coral (Millepora
alcicornis)
Nematocysts
Local pain and irritation
Supportive care
Hot water immersion
Pain management
Sea anemones (class
Anthozoa)
Nematocysts
Local pain and irritation, GI upset
Supportive care
Hot water immersion
Pain management
Blue-ringed octopus
(Hapalochlaena sp.)
Beak
Flaccid paralysis, respiratory failure,
death
Supportive care
Respiratory support
Cone snails (Conus
spp.)
Modified radula
Rapid paralysis, respiratory failure, death
Supportive care
Respiratory support
Sea urchin (class
Echinoidea)
Multiple spines
Local pain and irritation
Supportive care
Hot water immersion
Pain management
Wound care
Foreign body removal
Stonefish (Synaceia sp.)
Spines in dorsal,
pelvic, anal fins
Severe local pain and edema, GI upset,
cardiovascular instability, death
Supportive care
Hot water immersion
Pain management
Wound care
Antivenom
Other Scorpaenidae
fish (Pterois sp. and
Scorpaena sp.)
Spines in dorsal,
pelvic, anal fins
Local pain and swelling, GI upset
Supportive care
Hot water immersion
Pain management
Wound care
Stingray (class
Chondrichthyes)
Serrated tail barb
Severe local pain and edema
Supportive care
Hot water immersion
Pain management
Wound care
Sea snakes (genus
Hydrophiidae)
Small, front fangs
Ascending paralysis, muscle pain and
breakdown, respiratory failure, death
Supportive care
Respiratory support
Antivenom
GI, Gastrointestinal.
1219
SECTION XIV
BITES, STINGS, AND INJURIES FROM ANIMALS
traumatic marine injuries. Control of bleeding and wound
irrigation are important. Because infections can complicate
these injuries, prophylactic antibiotics should be considered.23
Injuries to tendons, ligaments, and other vital structures
should be evaluated and addressed.
FOLLOW-UP, NEXT STEPS IN CARE, AND PATIENT EDUCATION
Fig. 142.3 Retained stingray barb (arrow) in the foot.
cutting nature of the teeth. The severity of direct injuries from
stingray barbs depends on the location where the victim was
impaled.
DIFFERENTIAL DIAGNOSIS AND MEDICAL
DECISION MAKING
The offending organisms may or may not be known to the
victim, and concomitant envenomation should be considered.
Radiographic evaluation may be needed. The most important
medical decision to be made is whether the injury is severe
enough to warrant specialist care by a trauma, vascular, or
orthopedic surgeon.
TREATMENT
After initially addressing the airway, breathing, and circulation, direct wound care is usually sufficient to treat most
1220
All the marine food-borne illnesses are self-limited, although
amnestic shellfish poisoning has been linked to long-term
neurologic sequelae.24 Patients with suspected tetrodotoxin
poisoning should be admitted to the hospital for observation.
Most other patients who are asymptomatic after treatment can
be discharged. Those with ongoing or severe symptoms
should be admitted. The local public health department
should be informed of suspected cases of marine food-borne
poisoning.
The vast majority of marine envenomations will be selflimited and resolve with simple supportive care. Infection
from sea urchin spines, fish spines, and stingray barbs is well
documented, and prophylactic treatment with antibiotics
effective against pathogens such as Vibrio species should be
considered.21,22,25 Patients with persistent or severe pain may
need to be admitted, as will any patient with envenomation by
a potentially neurotoxic organism.
Serious injuries may need treatment by a trauma or orthopedic surgeon, either on an emergency basis or as an outpatient. Otherwise, good wound care measures should be
explained to the patient and return precautions focusing on
signs and symptoms of infection stressed.
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Fernandez I, Valladolid G, Varon J, et al. Encounters with venomous sea-life. J Emerg
Med 2011;40:103-12.
Isbister GK, Kiernan MC. Neurotoxic marine poisoning. Lancet Neurol
2005;4:219-28.
Noonburg GE. Management of extremity trauma and related infections occurring in
the aquatic environment. J Am Acad Orthop Surg 2005;13:243-53.
CHAPTER 142
Marine Food-Borne Poisoning, Envenomation, and Traumatic Injuries
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