Dangers of the deep

Today, with the tourist high season revving into gear, I’d like to look at another danger that tourists often ignore: getting up close and cosy with the residents of the deep.
Swimming in the tropical waters is as much part of a dream vacation in Southeast Asia as lazing on the beach and while a close and potentially lethal encounter with a Great White Shark is highly unlikely, the same can’t be said for jellyfish, sea snakes and stingrays.
Jellyfish are widely distributed through the tropical waters of Asia and the Pacific. Although most contacts with jellyfish induce nothing more than temporary and minor burning sensations, some stings can lead to more severe conditions, particularly if the victim is allergic to the toxin.
Some jellyfish can be extremely dangerous and among these is the box jellyfish, a highly poisonous species found in Australian and Indo-Pacific waters including the Gulf of Thailand.
Also known as the sea wasp, the box jellyfish is commonly found within 300 metres from the shore and has a distinctive 20-centimetre box-shaped bell with up to 60 tentacles measuring from a few cm up to three metres.
Tentacles possess millions of microscopic stinging cells that release potent and fast-acting venom upon contact with the skin. Box jellyfish stings are immediately painful and generate multiple reddish and lacerated injuries on the affected area. Without treatment the toxin can lead to acute cardiovascular shock. Deaths happen every year in Australia and a recent study conducted in Thailand has revealed at least 53 cases of toxic jellyfish stings with fatalities reported in the Andaman Sea and the Gulf of Thailand.
Minor jellyfish stings are treated by applying vinegar or lemon juice to the affected spots to neutralise the venom. If a box jellyfish is involved, it becomes a medical emergency. The first aid is similar to that of poisonous snakebite with immediate transfer to a medical centre, reassurance of the victims and immobilisation of the affected limbs to avoid the dissemination of the toxic substance in the body. A moderate compression bandage is applied on the lesions in an attempt to slow down the drainage of the venom from the lymphatic system. Specific anti-venom is given at the hospital.
Sea snakes are not infrequent encounters in tropical waters and while these reptiles are quite curious, they are generally not aggressive. If you come close to a sea snake, just move away steadily. A sea snake bite may be painless for the first few hours and no redness or swollen skin lesions may be visible.
General symptoms can occur from 30 minutes to 3 hours afterwards and include sweating, anxiety, abnormal vision, muscle and joints and paralysis.
Any sea snake envenomation must be considered as a medical emergency due to potentially life threatening complications.
Stingrays pose also a significant health hazard due to their flexible tail armed with saw-like venomous spines used exclusively in self-defense. The majority of stingray incidents happen when swimmers inadvertently step on them, resulting in a wound where the venom is injected through the skin. Instant and extreme pain occurs along with chills, vomiting, breathing difficulties, faintness and even short-lived paralysis.
Death is very rare but victims of stingray stings should be promptly transferred to a medical centre. First aid includes cleaning the wound with soap and clean water and the removal of all stingers with tweezers. The venom is heat sensitive so applying hot water for 30 minutes helps relieve the pain. As a preventive measure, shuffle your feet along the bottom as you enter the water to avoid stepping on the rays and to scare them away.

DR GERARD LALANDE is managing director of CEO-HEALTH, which |provides medical referrals for expatriates and customised executive medical check-ups in Thailand. He can be contacted at [email protected].