Background:   A major cause of HIV-related morbidity in sub-Saharan Africa is a commonly occurring, intensely pruritic  rash previously labeled the pruritic papular eruption of HIV. The rash consists of abundant hyperpigmented papules and nodules, and the resulting scars are disfiguring and stigmatizing.  The prevalence of PPE in Africans with HIV varies from 11% to 46%, depending on the geographic area.  Despite many reports over the past 20 years of the burden associated with pruritic papular eruption of HIV, its etiology had not been elucidated. 

Methods:   We performed a cross-sectional, descriptive biopsy study of HIV-infected patients with active clinical PPE enrolled by consecutive convenience sample from 2 clinics in Kampala, Uganda.  Each participant underwent physical exams by 2 dermatologists that included subjective assessments of the rash. Participants also had laboratory studies, a detailed epidemiologic questionnaire, and a skin biopsy of a new lesion evaluated by a blinded dermatopathologist.  Mean CD4 and eosinophil counts were compared using t-tests and ANOVA as appropriate.

Results:  Of 132 patients referred,102  (77%) mexhibited had pathological findings suggestive of arthropod bites on skin biopsy. Most of the remainder had nonspecific inflammatory changes (perivascular lymphocytes). CD4 counts in this population were low (median 46 cells/µL, mean 99, SD 129), and increasing clinical severity of PPE was associated with lower mean CD4 counts (146 mild, 92 moderate, 48 severe, p = 0.029). Patients with arthropod bites on biopsy had significantly higher mean serum eosinophil counts (454 vs 219 cells/µL, p = 0.046), and tended to have lower mean CD4 counts (88 vs 155, p = 0.057) than those without arthropod bites.

Conclusions:  The pruritic papular eruption of HIV in Uganda is most commonly a reaction to arthropod bites. The clinical severity of the rash and the likelihood of finding arthropod bites on biopsy are greater in those with lower CD4 counts.  We hypothesize that this condition reflects an altered and exaggerated immune response to arthropod antigens (such as mosquito saliva), analogous to increasing allergies to medications observed as CD4 counts fall in HIV⁺ patients.  Ongoing research will determine whether patients with arthropod-induced prurigo of HIV will benefit from mosquito nets, insect repellents, antiretroviral therapy, or other treatment.

Keywords: Pruritic Papular Eruption of HIV; Skin Complications of HIV; Uganda, Africa /Developing World