A diver, snorkeller or swimmer should never touch anything live.
Contact is often really painful and, depending on the toxicity of the organism, systemic symptoms may be expected.
Cleansing of the wound and removal of any foreign bodies should be done as first aid.
Problems may result from penetrating wounds, toxic effects of venom at the site of injury or from use as food.
Bites and stings of tropical sea life may involve venom causing toxic effects even in the absence of visible breaking of the skin. Broken skin is easily infected in warm water.
Some species of jellyfish, such as box jellyfish, irukandji jellyfish, Portuguese man-of-war jellyfish, blue ring octopus, and certain species of cone shells, as well as the stings of certain fish species, such as stonefish or scorpionfish, can be fatal.
First aid
Cleansing of the wound and removal of any foreign bodies, as far as possible (N.B. the person performing this must also protect himself from venomous spines or tentacles)
Neutralization of any venom
Dilute vinegar solution is often used.
Some venoms are thermolabile, meaning that immersing the site of injury in warm water (45°C) for more than 30 minutes will alleviate the symptoms, and pain, in particular.
Tetanus prophylaxis
Keep in mind the risk of infection.
Venoms will cause tissue destruction.
Tropical sea water contains gram-negative rods, in particular.
Very broad-spectrum antimicrobials, such as clindamycin + fluoroquinolone, are usually needed for the treatment of infected wounds (first generation cephalosporins are normally insufficient).
The source of the wound should be specified in the request for culture
Species-specific information
Jellyfish
When swimming in waters where dangerous jellyfish species occur, the skin should be protected from jellyfish stings, for example by wearing a wetsuit with long sleeves and legs.
Vinegar (acetic acid) solution is recommended for first aid.
People stung by box jellyfish, irukandji or Portuguese man-of-war jellyfish must be taken to hospital immediately. Two of three people stung by box jellyfish, for example, die.
Scorpionfish, lionfish and stonefish
Scorpionfish stings are very painful. The venom is thermolabile, meaning that rinsing and immersion of the affected area for half an hour in water at a temperature of 45°C will alleviate the symptoms and pain, in particular.
The person must naturally be taken out of the water because of the pain alone but also because being stung by stonefish causes respiratory and circulatory collapse.
The spine must be removed and the person removing it must protect himself.
People stung by stonefish, in particular, require respiratory and circulatory support, i.e., immediate hospitalization in practice. There is an antivenom available for stonefish venom.
Prophylactic antimicrobials are recommended at least for deep wounds and people with immune deficiency. Ciprofloxazin or sulpha trimethoprim, for example, can be used but not first generation cephalosporins. Broad-spectrum antimicrobials are needed to treat infected wounds.
The wounds will take a long time to heal, and spines sometimes need to be sought afterwards by imaging.
Echinoderms
People may step accidentally on echinoderms or hit them with their arms when diving or snorkelling. Protective footwear should be worn when wading in tropical waters.
The wounds are easily infected and spines sometimes need to be located by imaging to remove them.
Being stung by crown-of-thorns starfish causes immediate pain and erythema, the site of injury becoming swollen and numb. The site of the sting often turns dark blue for several weeks, and victims may suffer swollen lymph nodes and paralysis. In addition, they may have nausea and other systemic symptoms for many days. The toxin is thermolabile (i.e. the wound area should be immersed in warm/hot water), and any visible spines should be removed with tweezers, the person doing this protecting his hands. Broad-spectrum antimicrobial treatment is quite often necessary.
Sea urchin stings may contain toxins (flower urchin, Toxopneustes pileolus, and fire urchin, Asthenosoma varium, may be even fatal). Stings may lead to granuloma, synovitis and arthritis. At least any spines in the hands should be removed. If a sting is close to a joint, prophylactic antimicrobial therapy (e.g. clindamycin + ciprofloxazin) is recommended. The best way to remove spines from the thick epidermis in the soles of the feet is to spread 2% salicylate ointment on the skin for a couple of days to facilitate removal.
Other dangerous species
Some polyps, such as fire corals, may cause erythema and blistering as well as even severe pain and nausea for several days. Rinsing with seawater (fresh water would aggravate the symptoms), diluted acetic acid or isopropyl alcohol can be used for treatment. An attempt should be made to remove tentacles of cnidarians with tweezers.
Anyone who has been in contact with a blue ring octopus must be immediately hospitalized. This is considered one of the most poisonous animal species. The bite is usually painless but may cause respiratory arrest in less than an hour; the patient may be awake and unable to breathe. Early symptoms include paraesthesias, muscle weakness and cramps. The symptoms are caused by tetrodotoxin, a sodium channel blocker paralyzing the respiratory muscles (see here). Symptomatic (respirator) treatment should be given until recovery.
Stings by some cone shells, such as the geography cone, may be fatal. The symptoms include burning pain and tingling that may gradually spread all over the body. In half an hour, the victim will develop nausea and neurological symptoms. Respiratory and circulatory support should be provided until the toxin has been eliminated from the body.
Stingray barbs contain a thermolabile venom.
Wound infections
Vibrio vulnificus
Requires seawater with a temperature exceeding 18°C to grow.
May cause wound infections and food poisoning.
Considered to be the most dangerous food poisoning pathogen in the United States (1 400 cases per year reported to the CDC, 50% requiring hospital treatment).
The sources are raw fish, shellfish and molluscs (usually oysters).
Basically healthy people usually show ordinary symptoms of food poisoning.
People with immunodeficiency or liver disease are susceptible to sepsis with associated mortality as high as 50 to 60%.
Wound infections are typically associated with haemorrhagic blisters, necrotic fasciitis and sepsis. Mortality is about 20%. Fasciotomy and excision of the necrotic tissue are often required.
Antimicrobial resistance is appears to be increasing, but studies regarding different antimicrobials are scarce.
Vibrio parahaemolyticus
Usually causes gastrointestinal symptoms, sometimes wound infections (after hurricane Katrina, 3 cases of wound infection with Vibrio parahaemolyticus were detected, 2 of which fatal).
In addition, there are other species of vibrio causing wound infections.
Erysipelothrix insidiosa/rhusiopathiae
Erysipeloid Erysipeloid is caused by gram-positive rods. Handling of animals (including fish) is needed for infection.
May lead to sepsis and endocarditis particularly in alcoholics.
Sensitive to penicillin
Mycobacterium marinum
Fish-tank granuloma (picture 1) may also result from seashell scratch, for example.
Atypical mycobacteria; a long course of antimicrobials, sometimes surgery, is used for treatment
Aeromonas hydrophila
Gram-negative rods
Usually cause gastroenteritis but in immunocompromized people also cellulitis and sepsis.
Ingestion of poison
When poison has been ingested, the treatment is symptomatic.
Antiemetic drug for nausea and vomiting
Intravenous fluid therapy for dehydration (diarrhoea, vomiting) and decreased blood pressure
Intubation and mechanical ventilation for respiratory insufficiency
Activated charcoal may be beneficial in tetrodotoxin poisoning (see here).
Ciguatera poisoning
Basically from any tropical fish caught inside a coral reef, if the fish has fed on dinoflagellate algae or belongs to a food chain where these algae have been fed on at the beginning of the chain.
Between the 35th latitudes north and south in the Caribbean, Pacific and Indian Oceans. An estimated 500 000 cases per year. Ocean warming is expanding the endemic area.
Ciguatoxin is produced by dinoflagellate plankton algae (mainly Gambierdiscus toxicus).
The toxin cannot be destroyed by boiling, deep-freezing or drying.
Fish do not suffer from the toxin.
There is no way of recognizing toxic fish by appearance. If you see local people eat the fish without problem, you can conclude it is nontoxic. Gastrointestinal and neurological symptoms often begin during the meal already but usually within 12 (to 24) hours.
Nausea, vomiting, diarrhoea, abdominal pain
Typically paraesthesias, numbness and tingling, itching, motor pareses and even paralysis
Arthralgia, myalgia, sweating, salivation
Nearly all patients have a strange, typical symptom, i.e. a paradoxic sensation of heat when exposed to cold, such as cold water
Mortality approx. 1%
Recovery in 2 to 3 days but symptoms may persist for several weeks
Next time, the symptoms of intoxication will be more severe.
There is no specific treatment available.
Paralytic shellfish poisoning (PSP)
Alexandrium, Gymnodinium and Pyrodinium dinoflagellates (with "red algal bloom”) reported all over the world
Gastrointestinal and neurological symptoms, which may sometimes be fatal, arise within minutes.
Neurotoxic shellfish poisoning
Karenia brevis dinoflagellate of the Gulf of Mexico
Numbness, tingling, coordination problems, gastrointestinal symptoms for a few days. No fatalities have been reported.
Amnesic shellfish poisoning
Pseudo-nitzschia (also in the Baltic Sea) and Nitzschia navis-varingica diatoms
Gastrointestinal and neurological symptoms and amnesia, even fatalities (4%)
Tetrodotoxin poisoning
Tetrodotoxin is a neurotoxin found in, for example, pufferfish (Tetraodontidae). The highest levels of poison occur in the liver, but poison occurs also in other parts of the fish.
Some pufferfish have sharp teeth, but their bite is not poisonous.
Tetrodotoxin is produced by various bacteria living in the fish.
In Japan, pufferfish Fugu is served in restaurants with a special license.
Some neurotoxin remains even in appropriately prepared pufferfish. Deaths occur in Japan annually. There is no antidote.
Symptoms include various sensory disturbances, nausea and vomiting, gastrointestinal symptoms and difficulties in swallowing. A rapidly progressing muscular paralysis leads to paralysis of respiratory muscles and death.
Activated charcoal may be beneficial if taken quickly.
As the muscular paralysis progresses, respiratory insufficiency develops. The patient must be intubated and mechanically ventilated.
Due to the climate warming, tetrodotoxin-producing bacteria species have spread also to the Mediterranean sea and the Pacific ocean, and may occur also in other marine animals.