title: Sunlight is an important causative factor of recurrent herpes simplex.
abstract: 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.
authors.affiliation: Sun Clinic and Sun Care Institute Osaka, Division of Dermatology, Department of Molecular Medicine, Kobe University Graduate School of Medicine, Japan.
authors.forename: Masamitsu
authors.initials: M
authors.lastname: Ichihashi
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Nagai
authors.forename: Kayoko
authors.initials: K
authors.lastname: Matsunaga
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D005221:Fatigue / Q000150:complications; D005260:Female; D006561:Herpes Simplex / Q000209:etiology*; D018259:Herpesvirus 1, Human / Q000528:radiation effects*; D006801:Humans; D007223:Infant; D007899:Leisure Activities; D008297:Male; D008875:Middle Aged; D012008:Recurrence; D012621:Seasons; D012737:Sex Factors; D013472:Sunlight / Q000009:adverse effects*; D014466:Ultraviolet Rays / Q000009:adverse effects*