This observation is supported by the fact that most patients live at high altitudes (>1000 m above sea level), and the condition improves in many patients when they move to lower altitudes. However, some patients who are affected already live at sea level.18,19,27 •Some authors are considering a food photosensitizer or a nutritional selective deficiency as a cause; however, no evidence proves this theory.27

Treatment
Currently there is no cure for actinic prurigo, and treatment focuses on relieving the dermatologic symptoms, by way of topical steroid creams or systemic immunosuppressants. Prescribed treatments include:

topical creams such as Tacrolimus and Betamethasone. systemic immunosuppressants such as Prednisone. In some cases, Thalidomide has proven to be effective in controlling the symptoms of actinic prurigo.All patients with AP are encouraged to minimize sun exposure, and to use strong sunscreen throughout the year, and even on cloudy or overcast days, as UVA light, unlike UVB light, is able to penetrate cloud cover and remains constant throughout the day. Alternative treatment methods might include UV Hardening, Meditation and/or cognitive behavioral therapy. UV-A desensitization  phototherapy has also been shown to be effective in cases. History
Actinic prurigo (AP) was first described by Escalona in Mexico, in 1954. See also
Photosensitivity with HIV infection
List of human leukocyte antigen alleles associated with cutaneous conditions
Hydroa vacciniforme

References
External links
http://dermnetnz.org/reactions/actinic-prurigo.html
Actinic Prurigo at eMedicine
Torres-Alvarez, B; Baranda, L; Fuentes, C; Delgado, C; Santos-Martinez, L; Portales-Perez, D; Moncada, B; Gonzalez-Amaro, R (January 1998). "An immunohistochemical study of UV-induced skin lesions in actinic prurigo. Resistance of langerhans cells to UV light". European Journal of Dermatology.
8 (1): 24–8. PMID 9649710. INIST:2157125. Polymorphous light eruption – Mayo Clinic