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Cutis. 2004 Nov;74(5 Suppl):14-8.

Sunlight is an important causative factor of recurrent herpes simplex.

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Sun Clinic and Sun Care Institute Osaka, Division of Dermatology, Department of Molecular Medicine, Kobe University Graduate School of Medicine, Japan.


To evaluate the role of exposure to solar UV radiation (UVR) in primary and recurrent herpes simplex virus 1 (HSV-1) infections, we investigated the self-reported cause of infection among diagnosed patients in Hyogo Prefecture, Japan. Among 4295 infected patients, 3678 had HSV-1, and 2656 of those patients (72.2%) had a recurrent flare-up. Fatigue was the most commonly reported cause of a flare-up among all patients, followed by the common cold and sun exposure. Sun-induced HSV-1 flare-up was reported by 10.4% of the total study population. However, this increased to 19.7% among patients diagnosed in July and August, to 28% among patients younger than 30 years diagnosed in July and August, and to 40% among patients younger than 30 years diagnosed in July and August with a recurrent infection. These results suggest the important role of solar UVR in the development of recurrent HSV-1, possibly due to UVR-induced immunosuppression or direct reactivation of HSV-1 in the neural ganglia.

[Indexed for MEDLINE]

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