Mary L. Sy, MD



An 11-year-old boy presented for evaluation of an itchy rash that developed during a ski vacation. He mentioned that he had enjoyed a hot tub during his trip.

The itchy rash is hot tub folliculitis-a superficial infection of the hair follicle caused by 

, usually serotype 0:11. The bacteria can be found in hot tubs, whirlpools, or swimming pools. Hot water, aeration, and turbulence encourage growth of the organism. Patients may note the onset of the rash within 6 hours or up to several days after exposure. The rash is a pruritic pustular or papular eruption that is most intense in areas covered by a bathing suit. Occasionally, erythematous or violaceous nodules are present. Fever, lymphadenopathy, and malaise occur in a small number of cases. The rash resolves spontaneously in 1 to 2 weeks and only rarely requires treatment with topical or oral antipseudomonal medication.

Adequate bacterial surveillance and maintenance of hot tubs, whirlpools, and swimming pools are key, although avoidance of affected pools or tubs is the best prevention. Pools and tubs suspected of harboring 

 should be cultured and sterilized when results are positive. Immunocompromised persons are susceptible to the more serious complications of folliculitis (eg, cellulitis) and should avoid hot tubs entirely.


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Articles

An 11-year-old boy presented for evaluation of an itchy rash that developed during a ski vacation.

Hot Tub Folliculitis in an 11-Year-Old Boy



This 10-year-old boy presented for evaluation of a rash that developed during a spring vacation on Florida's Atlantic coast. After he had been swimming in the ocean, a pruritic, erythematous, papular rash developed on his trunk, axillae, and groin. Approximately 24 hours after the onset of the rash, he experienced malaise, chills, and a sore throat. His past medical history was unremarkable. He had been fully immunized and had had varicella infection.

This boy has seabather's eruption, a pruritic dermatitis that occurs after exposure to seawater that contains certain species of jellyfish-particularly the larval form of the thimble jellyfish (

). The larvae are found in seawater in areas where this eruption is endemic, such as the Caribbean and the Atlantic coast of Florida, where this boy had vacationed. The jellyfish are found in these warm waters from March through August, with peak concentrations in May and June. The first written reports of this disease came from Florida's Delray Beach.

The jellyfish larvae contain venom-filled barbs that fire their venom into the skin when the larvae become trapped under a bathing suit. Changes in osmotic pressure, such as air-drying or showering with fresh water, also trigger the barb-firing process. The venom causes a local toxic reaction and can precipitate a systemic hypersensitivity reaction. The local reaction-an erythematous, pruritic, papular dermatitis-may be especially heavy on the skin under the bathing suit and in areas covered with hair, such as the axillae. It appears 4 to 48 hours after exposure to infested seawater. Systemic symptoms are more common in children than adults and include malaise, fever, sore throat, abdominal pain, headache, cough, and diarrhea.

Both the rash and systemic symptoms generally resolve in 1 to 2 weeks. Treatment is supportive and includes antihistamines and topical corticosteroids. Systemic corticosteroids are reserved for severe cases.

The best preventive measure is to avoid swimming in infested water altogether. Those who choose to swim in potentially infested waters need to be aware that the wearing of T-shirts for ultraviolet protection increases the risk of getting seabather's eruption. Bathers should instead use a waterproof sunblock for ultraviolet protection. While sunblock affords no protection against the jellyfish larvae, it does not increase the risk of trapping the larvae against the skin, as T-shirts do. Bathers should shower as soon as possible after swimming, without their bathing suits, which should be washed in detergent and heat-dried.

This 10-year-old boy presented for evaluation of a rash that developed during a spring vacation on Florida's Atlantic coast.

Seabather's Eruption

) each presented for evaluation of an erythematous, pruritic, papular rash that developed after swimming in a Wisconsin lake. Each child was otherwise completely healthy.

Both children have cercarial dermatitis, commonly known as swimmer's itch. This is a hypersensitivity reaction that occurs after exposure to schistosome larvae in freshwater lakes. Schistosome eggs (of trematodes, genera 

) are passed into freshwater lakes via bird feces. The eggs hatch and develop into the larval stage called miracidia, which infect their intermediate host, freshwater mollusks. The miracidia transform into a second larval form called cercaria, which leave the mollusks and infect birds either by being ingested or penetrating their skin. Cercaria can also penetrate human skin and may infect persons swimming in infested water. The cercaria are unable to complete their life cycle in humans and die in the epidermis.

Although most common in the Great Lakes region of the United States, outbreaks occur during the summer months throughout the world. As the skin dries and the cercaria penetrate the epidermis, patients often describe the initial itching sensation. Small macules may be visible transiently at the site of penetration. Several days to 2 weeks after initial exposure, a mild to moderately pruritic, erythematous, papular, sometimes pustular eruption develops on any skin that had been exposed to infested water. In sensitized persons, the eruption develops within hours of exposure. The onset and intensity of the eruption correspond to the degree of sensitization. The rash peaks within 48 to 72 hours and usually resolves within 1 week.

Treatment is supportive and consists of oral and topical antihistamines and topical corticosteroids. Anthelmintic therapy is not indicated for this self-limited condition.

Preventive measures include avoiding exposure to fresh water that contains mollusks and toweling off immediately after swimming (since penetration into the skin occurs during evaporation).

A 6-year-old girl and an 11-year-old boy each presented for evaluation of an erythematous, pruritic, papular rash that developed after swimming in a Wisconsin lake.

Author | Mary L. Sy, MD

Articles

Hot Tub Folliculitis in an 11-Year-Old Boy

Seabather's Eruption

Swimmer's Itch