For example, in 2001 less than 1% of the sexually active urban population in Africa had been tested, and this proportion is even lower in rural populations. Furthermore, in 2001 only 0.5% of pregnant women attending urban health facilities were counselled, tested or received their test results. Again, this proportion is even lower in rural health facilities. Since donors may therefore be unaware of their infection, donor blood and blood products used in medicine and medical research are routinely screened for HIV.HIV-1 testing is initially done using an enzyme-linked immunosorbent assay (ELISA) to detect antibodies to HIV-1. Specimens with a non-reactive result from the initial ELISA are considered HIV-negative, unless new exposure to an infected partner or partner of unknown HIV status has occurred. Specimens with a reactive ELISA result are retested in duplicate. If the result of either duplicate test is reactive, the specimen is reported as repeatedly reactive and undergoes confirmatory testing with a more specific supplemental test (e.g., a polymerase chain reaction (PCR), western blot or, less commonly, an immunofluorescence assay (IFA)). Only specimens that are repeatedly reactive by ELISA and positive by IFA or PCR or reactive by western blot are considered HIV-positive and indicative of HIV infection. Specimens that are repeatedly ELISA-reactive occasionally provide an indeterminate western blot result, which may be either an incomplete antibody response to HIV in an infected person or nonspecific reactions in an uninfected person. Although IFA can be used to confirm infection in these ambiguous cases, this assay is not widely used.
When a decision to undertake this is made, a small area of the frequently affected skin is exposed to varying doses of UVA and minimal erythema dose (MED) (amount of UV radiation that will produce minimal redness of skin within a few hours following exposure) of broadband UVB for three consecutive days. An examination of the skin to detect the rash is made, however, up to 40% have false negative responses. Biopsy findings
Depending on the clinical signs, histology of a skin biopsy may vary. There may be oedema in the epidermis with a dense superficial and deep lymphocytic infiltrate without vasculitis. Recently appearing lesions may show neutrophils. Spongiosis and vesicle formation may also be present. Direct immunofluorescence testing is negative. Differential diagnosis
The photosensitivity connected with lupus erythematosus is the main condition that may appear like PLE. However, the rash of lupus is inclined to be more persistent. PLE does not increase the risk of lupus.Other similar appearing conditions are solar urticaria, which has a shorter duration, the eczema-like condition, photosensitive dermatitis, and photosensitivity drug reaction.Prickly heat, which is caused by warm weather or heat is not the same as PLE.Photosensitivity is also found in some of the porphyrias. Nearly all cases of porphyria cutanea tarda exhibit blister formation on the skin within 2–4 days of light exposure. Variegate porphyria and hereditary coproporphyria can also exhibit symptoms of light-induced blisters.