Marine Envenomation - An Overview

Introduction:

Most marine envenomations are mild and do not show life-threatening reactions. However, the pediatric population is at a higher risk of developing severe reactions. They can cause a series of clinical systemic reactions through the defense mechanism and inadvertent human contact, leading to morbidity and mortality.

Which Marine Creatures Cause Marine Envenomation?

• Jellyfish.

• Sea snake.

• Cone snail.

• Stonefish.

• Scorpionfish.

• Lionfish.

• Stingray.

• Octopus.

• Sea urchin.

• Irukandji.

• Physalia.

• Geography cone.

How Is Venom Delivered?

• Cnidocytes: The cnidocyte is a specialized cell containing cnidocysts that facilitate venom delivery. Each tentacle of cnidarian has thousands of cnidocytes. A harpoon is released from the cnidocyst due to increased osmotic pressure and chemical changes, penetrating deep into the epidermis, dermis, and sometimes the capillaries.

• Spines: Certain vertebrates and invertebrates use spines to defend and release their venom into their prey. Sea urchins and stars have a venom apparatus connected to the spine containing calcium carbonate. The spines can be very dangerous by breaking off inside the victim’s skin and retained as a foreign body. The cone snails use a radula, a dental structure to penetrate the victim’s skin and deliver the venom. Stingrays possess a spine located at the tail end that detaches, gets embedded in the victim, and delivers venom. Stonefish have venom glands used for delivery.

• Bites: The biting mechanism is usually employed by both vertebrates and invertebrates. For example, blue-ringed octopods use bony beaks to deliver toxins to the victim. Sea snakes are similar to terrestrial cobras in delivering venom from the glands through a bite.

What Are the Clinical Manifestations of Marine Envenomation?

• Box Jellyfish: Box jellyfish's venom causes hemolytic and neurotoxic effects, causing necrosis and hypotension.

• Stonefish: The venom from stonefish has hyaluronidase activity and causes hypotension, hemolysis, and nerve paralysis. The injuries caused by stonefish are found to be fatal. They have been sustained by individuals fishing for food.

• Portuguese Man-of-War or Physalia: It causes hemolysis, swelling, and necrosis. Extreme pain is experienced following the attack by the sting. The area attacked shows swollen welts appearing as a linear papular rash.

• Geography Cone: This is the most dangerous species known to harm humans. The common symptoms after a geography cone bite are paralysis at the site of injury, double vision, dizziness, and mouth numbness. Sometimes, the symptoms may be severe, requiring ventilatory support.

• Blue-Ringed Octopus: They can cause paralysis of respiratory muscles.

How to Diagnose Marine Envenomation?

There are no specific diagnostic criteria for identifying marine envenomation. Instead, the diagnosis is based on the patient’s history and identification of the aquatic creature responsible for the victim.

How to Treat Marine Envenomation?

• Immerse the Wound in Hot Water: The immersion of the wound in hot water would help to control the pain in that area. It deactivates the heat-liable proteins and enzymes, leading to minimization of systemic effects. The victim is inserted in hot water for 30 to 90 minutes or until pain relieves. If a basin is used, the temperature of the water is monitored, and hot water is added when required. The temperature should remain controlled and should not cause any burns. Showering is also preferable to eliminate the stinging cells attached to the skin and maintain a constant temperature. Before hot water immersion, the tentacles should be washed off using seawater. In addition, if the victim is stung by box jellyfish, the area is immersed in vinegar for at least 30 seconds to inactivate the nematocyst attached to the skin. Lidocaine solution can also inhibit the discharge from nematocyst and provides a local anesthetic effect in that area.

• Pain Control: A regional nerve block with Lidocaine is necessary if hot water immersion does not work. Some individuals with low pain thresholds can be treated with additional parenteral medications. Some other remedies include local injection of potassium permanganate, alcohol, and congo red, which can lead to tissue damage and are not commonly used.

• Irrigate the Wounds, Remove Spines, and Debride Necrotic Tissues: Removing spines would help prevent systemic effects. However, the retained spines can lead to microbial infection and complicated wound healing. Therefore, the spines have to be handled carefully to avoid crushing them. To check for any left outs, radiographs are recommended. Shaving cream and a razor can be used if there are invisible stinging units. The necrotic tissue should also be debrided completely to prevent secondary infection.

• Prescribe Antibiotics: Prophylactic antibiotics are recommended for large lacerations, contaminated wounds, retained foreign materials, and deep wounds. Ciprofloxacin, Doxycycline, and Trimethoprim are most commonly used. For patients with rapidly progressing infections, the oral and parenteral combination is recommended.

• Observe for Systemic Symptoms: The patients should be observed for about three to four hours for systemic symptoms. If respiratory distress, hypotension, muscle cramping, and arrhythmias develop, the patient requires supportive care. Only a few antivenoms are available for box jellyfish, stonefish, sea snakes, and tiger snakes.

How to Treat Penetrating Wounds?

The primary approach for treating penetrating wounds is pain management. However, in the case of patients with other medical abnormalities, advanced medical care is required. First, the animal's spine from the affected area is removed and placed in hot water. Once the pain subsides, clean the area with saline. In the case of a large amount of venom injected into the area, a compression bandage followed by immobilization is required to prevent the circulation of venom into the body.

How to Prevent Marine Envenomation?

• Avoid touching marine creatures.

• Get to know about the various marine creatures in the area.

• Use protective shoes when you swim inside water.

• Have a first-aid kit containing pain, fever, allergy medications, band-aids, gauze, antibiotic ointment, sunscreen, and tweezers.

Conclusion:

Before setting up a trip into the sea, pack up the protective materials and avoid disturbing marine life. Disturbing the creatures causes harm to humans, and can lead to serious life-threatening complications. And so be safe underwater.