Use of sequential lateral flow assays to diagnose cryptococcal infection among people living with HIV in Monrovia, Liberia.

Abstract

Cryptococcal meningitis is one of the top causes of morbidity and mortality in people living with HIV/AIDS. In high prevalence regions, current recommendations are to screen individuals with blood CD4+ T cell counts less than 200 cells/µl for serum cryptococcal antigen (CrAg) and then preemptively treat those who test positive for presumed cryptococcosis. However, in many low-resource settings, including Monrovia, Liberia, flow cytometric CD4 assays are not readily available. We tested subjects with known HIV infection using a lateral flow assay (LFA), which provides a semi-quantitative determination of whether the blood CD4+ T cell count is ≤200 cells/µl. Subjects with counts ≤200 cells/µl were then tested with an LFA that detects CrAg. Of the 500 HIV+ subjects tested, 201 (40.2%) had blood CD4+ T cell count ≤200. Of those, 82/201 (40.7%) were serum CrAg+. Subjects who were serum CrAg+ were more likely to have a Glasgow Coma Score <15, whereas subjects who were CrAg- were more likely to be HIV-2+. Lumbar punctures were performed on 61 serum CrAg+ subjects; 30/61 (49.2%) subjects were cerebrospinal fluid CrAg+. Thus, sequential point-of-care testing enabled the diagnosis of cryptococcosis in HIV+ individuals with blood CD4 T cell counts ≤200 cells/µl. As diagnostic testing informs life-saving therapies, it is imperative that these assays are made readily available in resource-poor settings.