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Crab Attack: Battling an allergic reaction alone
Posted: Wednesday, June 27, 2012 7:08 PM
Joined: 02/05/2008
Posts: 392

It was a beautiful, sunny morning moored off a remote paradisiacal island in the Indian Ocean. The crew geared up to take the guests out to spend their day exploring and Deckhand Joe was left behind to mind the vessel. To pass the time, Joe headed to the galley for a mid-morning snack. An array of cakes, meat, fish, chicken and crab, from last evening’s dinner were the perfect choice. Relaxed and absent-minded, Joe took a crab cake, but that was a big mistake. Joe is allergic to crab.

A crab allergy, which can range from mild to life-threatening, is one of the most common food allergies in adults and can cause some of the most severe allergic reactions, including anaphylaxis. Anaphylaxis is an overreaction of the immune system when trying to fight against substances erroneously recognized as threats, such as an allergen. In Joe’s case, the crab protein triggered an exaggerated and unnecessary immune response.

The underlying common denominator in an anaphylactic reaction is the dilation of blood vessels. This dilatation allows for fluid to exit the bloodstream into the tissues, causing local swelling. Depending on the location, the result could vary from a “puffy face” with lips and/or eyelid swelling to larynx and bronchi swelling, which would stifle the person’s ability to breathe. In the later instance, fatal respiratory distress could occur if the abnormal process cannot be stopped in a timely manner.   

In addition, the extreme dilatation of the blood vessels can affect blood pressure, causing it to drop below the level required to sustain blood perfusion to critical organs, such as brain and heart. The result is anaphylactic shock, another life-threatening symptom.

Treatment requires counteracting the blood vessel dilatation by means of a vasoconstrictor substance. Epinephrine, also known as adrenaline, is the classic remedy.

From the first bite of the ill-chosen crab cake, Joe began to feel the unmistakable symptoms of a reaction. Alone on the yacht, Joe immediately called the vessel’s telemedicine provider. From previous experience, he knew every second mattered if he was to successfully control the situation.

The telemedicine physician referred Joe to the location of the epinephrine in the yacht’s medical kit. Time was of the essence, and the physician remained on the call, coaching Joe in the preparation of the syringe and the proper way to administer the injection of epinephrine to counteract the effects of the allergic reaction. 

Through quick action, a cool head and utilization of the vessel’s medical resources, Joe successfully saved his own life that day.

Joe was extremely fortunate. He had the medical training, knew who to call in an emergency, and kept calm. He also knew he never wanted himself or his crewmates to have to go through a similar situation. It is important for crewmembers to convey their food, or any other, allergies to all on board.

Auto-injectors of epinephrine are a great addition to the onboard medical supply.  The medical devices, such brands are Anapen®, Twinject® and EpiPen®, are pre-filled syringes of epinephrine that inject the precise dosage. The needle penetrates the exact depth into the muscle at the pull of a “trigger,” even through clothes. The auto-injector method saves precious minutes.

In addition, it is important for crew to go through various medial emergency drills on board to ensure all crewmembers are aware of all procedures, as safety is a priority. 


By Dr. Paulo M. Alves, the Vice President of Maritime Health at MedAire. MedAire provides medical advice, training, and medical equipment for crew at sea and ashore.