It’s Sea Lice Season in the Caribbean Again

Have you ever emerged from a great dive in Caribbean waters with more than the itch to dive again? It could be a burning physical itch that ruins your mood, your day and even the rest of your dive trip.

This burning itch, known as “sea lice,” is found in popular dive spots in Florida and the Caribbean. Common symptoms are itchy skin eruptions and dimesized blisters. They’re found primarily on body parts covered by swimwear but lesions can also appear on arms, legs and the neck. Symptoms will appear within 24 hours after exposure to sea lice and will persist for several days, although there have been some cases lasting several weeks. Symptoms can include fever, chills, headaches, nausea and vomiting.

The term “sea lice” is a misnomer since the primary offenders in Florida and Caribbean waters are the larvae of the thimble jellyfish. Only half a millimeter in length, they can find their way into bathing suits, become trapped against the skin and sting. Since many sea lice symptoms are mild or consistent with other illnesses, diagnosis is sometimes difficult unless the doctor knows of a diver’s exposure to contaminated water.

April through July are the months when sea lice are most prevalent. The larvae are most concentrated in shallow waters, between the surface and depths of 10 to 15 feet. If you’re diving during sea lice season, ask the dive operator if there have been any recent encounters. If so, make a quick descent once you enter the water and, on the way back, make your shallow water stop around 20 feet instead of 10. The best prevention method is protection by wetsuit or skinsuit. A product called Sea Safe, formulated to prevent jellyfish stings, has also been reported as an excellent preventive.

If you’re diving or swimming in sea lice-infested waters, remove your wetsuit, dive skin or bathing suit before showering because fresh water may discharge the larvae trapped in the fabric. Even so, sea lice may remain in clothing; Divers Alert Network has reported cases of sea lice recurring when the same bathing suit is worn again.

If you do start feeling the burn, immediately apply a mixture of isopropyl alcohol and vinegar. Lacking that, try pure vinegar or even Windex. Next, apply a hydrocortisone cream or lotion twice a day. As with most allergic skin reactions, a dose of oral antihistamine like Benadryl or Claritin can help, but factor in how side effects like drowsiness could affect your diving. Sometimes rashes will clear spontaneously, but others may need antihistamines and antipruritic (anti-itching) agents, and severe cases may require cortisone tablets or injections. So if sea lice stings go beyond mild to moderate symptoms, it’s time to find a physician.