The cryptococcal antigen lateral flow assay: A point-of-care diagnostic at an opportune time

Abstract

Cryptococcal meningitis is a devastating HIV-related opportunistic infection, affecting nearly 1 million individuals and causing over 500 000 deaths each year. The burden of disease is greatest in sub-Saharan Africa and Southeast Asia, where cryptococcal disease is the most common cause of meningitis. Rapid, accurate and affordable diagnosis of cryptococcal disease has been lacking in many of the most heavily affected areas. Here, we review a point-of-care assay for cryptococcal disease, the dipstick-formatted cryptococcal antigen lateral flow assay (LFA) (IMMY, Norman, OK). In comparison to culture, the assay is 99.5% sensitive and 98% specific. In comparison to other commercially available tests for cryptococcal antigen, the LFA has equal or superior sensitivity and specificity in CSF, plasma and serum samples. We discuss potential applications for the use of the assay in resource-limited settings, including what is likely to be an important role of the LFA in screening for early cryptococcal infection before clinical disease and in evaluating pre-emptive treatment.

• Cryptococcosis
• cryptococcal antigen
• cryptococcal meningitis
• fungal diagnosis
• lateral flow assay

Declaration of interest

Salary support was provided by the National Institutes of Health (NIH), USA (NIAID NRSA 5F32AI098584-02) to M. W. T. At the request of the investigators, IMMY has provided CrAg LFA kits to M. W. T. and D. A. K. for NIH-supported AIDS Clinical Trials Group studies, and to M. W. T., K. V. C. and D. A. S. for use in an experimental animal model of cryptococcal disease to study IRIS, funded by a Polin AIDS grant to the California Institute for Medical Research.