What is Seabathers Eruption (Sea Lice)?

Seabather’s Eruption (SBE), also known as “Sea Lice,” is an itchy skin rash.
People typically get it on parts of their bodies covered by a bathing suit or where their skin rubs against clothing or itself after they swim in the ocean.
This rash is caused by two types of tiny sea creatures: the thimble jellyfish (Linuche unguiculata) and a kind of sea anemone (Edwardsiella lineata).
Both these creatures are small enough to get trapped under swimwear.
When these creatures are squeezed or exposed to fresh water, they release a special organ called a nemocyte, which produces a variety of toxic chemicals.
These chemicals cause an immune response, leading to the rash.
The thimble jellyfish is mostly found along the southeast coast of the United States, the Gulf of Mexico, the Caribbean, Brazil, and Papua New Guinea.
The sea anemone is often the cause of SBE on the east coast of the United States, from the mid-Atlantic area up through New York.
It was once thought that only the immature thimble jellyfish caused SBE, but evidence suggests that other stages of this creature’s life cycle might be involved too.
This rash is most common during the spring and summer, particularly in May and June.
Children under 15 years old and surfers are at higher risk for getting this rash, probably because they spend more time in the water.
Places on the body where clothing rubs against the skin, like the chest, armpits, and stomach, are common areas for surfers to get this rash.
People who have had SBE before are at higher risk for getting it again, and usually, their symptoms are more severe.

What Causes Seabathers Eruption (Sea Lice)?

Sea Bather’s Eruption (SBE) is caused by marine creatures known as L. unguiculata and E. lineata. These small organisms can get trapped under your swimsuit after you come out of the water. The pressure between your skin and the swimsuit triggers these organisms to release nemocytes, which are specialized cells that contain harmful toxins.

When these toxins make contact with your skin, they can cause a type of poisoning known as envenomation, which is the process of toxins from animals entering the body and causing harm. This leads your immune system to respond and fight against these foreign toxins, much like it would a bacteria or virus. This immune response is what causes the symptoms of Sea Bather’s Eruption.

Risk Factors and Frequency for Seabathers Eruption (Sea Lice)

Being under the age of 15
Having a history of SBE
Going surfing

Signs and Symptoms of Seabathers Eruption (Sea Lice)

Seabather’s eruption (SBE) is a condition that usually begins with itching or a stinging sensation after leaving the water. Some people may even notice this while they are still in the ocean. This condition is typified by red, itching bumps that could develop into small, fluid-filled blisters or pustules. Because of the intense itching, the lesions might be hard to spot, especially if they’ve been scratched and potentially infected.

The lesions usually appear under the bathing suit, particularly around the waistband or other areas where the swimsuit exerts pressure. You may also notice these lesions on parts of the body that experience friction, such as the armpits, or the chest and abdomen of surfers. People with hairy chests might also find lesions in that area. The lesions typically last for about two weeks but can persist for over a month in some cases.

While generally, there are no severe bodywide symptoms linked to SBE, some people have reported experiencing fever, feeling unwell, nausea, vomiting, and stomach cramps. These symptoms have typically lasted less than a week. There was one reported case where a patient experienced blurred vision that improved after a week without any lasting effects.

SBE is diagnosed based on the visible symptoms, with lab tests and biopsies usually not necessary. However, if the need arises, tests for certain marine organisms causing SBE can be carried out a few weeks after coming in contact with the water or in those who have been re-exposed. It is noteworthy that the rash could recur if the bathing suit is worn again without being washed. Thus, it is advised to always wash swimwear before using it again.

Testing for Seabathers Eruption (Sea Lice)

Seabather’s eruption is a rash that can occur after you’ve been swimming in the ocean. Doctors can usually diagnose it based on the pattern and location of the rash on your skin and your recent history of ocean swimming. Special lab tests, skin biopsies, or x-ray studies usually aren’t helpful for diagnosing this condition.

There is a test for exposure to a certain marine organism associated with seabather’s eruption, called L. unguiculate, but a positive result just means you’ve been exposed to this organism. It does not specifically diagnose seabather’s eruption, nor can a biopsy (a procedure where a small piece of skin is removed for examination). The appearance of a skin sample under a microscope in this condition can’t be differentiated from that in an insect bite.

If your doctor suspects you have seabather’s eruption, they would perform a thorough skin examination to note the pattern and location of the rash. They would also ask about any recent ocean bathing activities. Thus, accurate diagnosis of seabather’s eruption depends largely on a careful review of your symptoms and recent activities, along with a thorough physical examination.

Treatment Options for Seabathers Eruption (Sea Lice)

If you get stung by a sea creature and then immediately leave the water, rinsing the area with a 5% vinegar solution can help to deactivate any venom cells that haven’t yet released their toxins. However, this won’t stop a rash from forming if one is going to appear. Typically, people seek medical help after a rash has already developed.

These rashes are usually treated with antihistamine pills and skin creams that contain steroids to reduce the inflammation. The antihistamine named fexofenadine is often used because it can ease the skin itching during the day. For nighttime, diphenhydramine may be recommended because it can make you sleepy, and this is less of a concern at night.

Steroid creams are also commonly used. The type and strength of steroid cream prescribed is often dependent on where on the body the rash has appeared. Doctors will usually avoid prescribing strong steroid creams for rashes that have developed in sensitive areas like the armpit, groin, or face because the risks of side effects in these areas are higher. For rashes on other parts of the body, a strong steroid cream such as clobetasol might be recommended.

To prevent any remaining venom cells from causing further harm, it’s also advised to wash your swimsuit thoroughly in hot water with detergent.

When diagnosing a skin condition known as SBE, doctors might also consider other conditions that have similar symptoms. These conditions include:

Arthropod Bites: These are insect bites that can be hard to distinguish from SBE. However, there’s a typical pattern involving 3 bite marks that’s different from SBE, and people with these bites usually have a history of outdoor exposure.
Folliculitis: This is a skin condition that commonly affects the chest and back. It usually has more of a pustular aspect in various stages of healing compared to SBE, though it can be hard to tell apart if it’s located in the area covered by a bathing suit.
Swimmer’s Itch: This is similar to SBE, but can be differentiated based on the distribution of the skin lesions and the individual’s history. Swimmer’s itch results from larval schistosomes that invade the skin. They mostly affect exposed skin areas and are typically associated with swimming in lakes or rivers.
Seaweed Dermatitis: This condition also resembles SBE but is caused by fragments of seaweed caught under the bathing suit. If a person has been swimming where there are seaweed blooms, this could help separate this condition from SBE.
Allergic Contact Dermatitis: This type of skin irritation occurs when the skin has come into contact with an allergen.

Therefore, it’s important for doctors to carefully review these possibilities and conduct proper tests to make an accurate diagnosis.