High prevalence of indeterminate Western blot tests for antibodies to HIV-1 in Tanzania

Abstract

In early 1988 physicians from the Muhimbili Medical Centre in Morogoro Tanzania collected sera from 106 individuals to evaluate the application of the Western blot test as a confirmatory test for HIV-1 and HIV-2 in Africa. the physicians divided the samples between a low risk group (dental patients pregnant women and health clinics staff) and a high risk group (inpatients). Laboratory personnel tested all samples for HIV-1 and HIV-2 using a commercial ELISA test. Further no matter what the result of the ELISA test they tested all samples using HIV-1 and HIV-2 Western Blot tests. 15 samples continuously tested positive on 2 of the 4 anti-HIV-1 ELISA kits. Further 11 samples tested positive by HIV-1 Western Blot test for an overall prevalence of 10%. The researchers considered this a high prevalence. Moreover a high prevalence (31%) of the sera could not be determined as positive or negative using the HIV-1 Western Blot test. In this group 82% contained gag-related bands only. 58% were negative using the HIV-1 Western Blot test. 23 samples repeatedly tested reactive using the HIV- 2 ELISA test especially those in the HIV-1 Western Blot positive group. Since no HIV-2 incidence was found HIV-2 cannot explain the indeterminate HIV-1 Western Blot results. Additional research to interpret the nature and significance of these indeterminate results is warranted. The researchers suggest that longitudinal studies be conducted to determine if indeterminate results indicate a true HIV infection.