Epidemiological investigation and follow-up study of indeterminate HIV antibody test results in Jiading, Shanghai

ObjectiveTo investigate the rate and the population distribution of subjects with indeterminate result of HIV antibody test and to understand the relationships between the western blot(WB)banding patterns and HIV infection through follow-up reexamination.

MethodsSamples with indeterminate results of HIV antibody test were collected by Jiading Center for Disease Control and Prevention from 2013 to 2017. They were used for analysis of the source, the distribution of Western blotting band pattern and the follow-up results.

ResultsAmong 698 samples required to be re-tested for confirmation of HIV infection, 151(21.63%)showed indeterminate WB test results. There were 18 types of WB band in 151 HIV antibody-indeterminate samples. The most common band types, accounting for 79.47%, were p24, gp160, and gp160p24. One hundred(among 151)subjects were followed up and the success follow-up rate was 50.00%. Among them, 28(56.00%)samples were still with indeterminate results of HIV antibody, 11(22.00% turned to be negative and 11(22.00%)turned to positive. The follow-up confirmatory tests showed that 67.86% of the samples with p24 band were still with indeterminate results and 40.00% of the samples with gp160 band became HIV antibody-negative. The samples with one of the three band patterns of gp160gp120p24, gp160p24p17 and gp160gp120p66p51 all became HIV antibody-positive.

ConclusionThe detection rate of indeterminate HIV antibody results varies in different populations. Positive conversion rates with different WB band patterns are different. Follow-up of the populations with specific WB band patterns should be strengthened to detect HIV infection cases as early as possible.