Diagnostic performance of lateral flow antigen tests versus latex agglutination for cryptococcosis in dogs and cats.

Abstract

OBJECTIVE: To investigate the diagnostic utility of 2 point-of-care cryptococcal antigen (CrAg) lateral flow assays (LFAs; Dynamiker Biotechnology Co Ltd and IMMY) for the diagnosis of cryptococcosis in dogs and cats using a latex CrAg agglutination test (Cryptococcal Antigen Latex Agglutination System; Meridian Bioscience) as the reference standard. METHODS: Serum samples from 21 dogs and cats considered to be infected with cryptococcus and 30 animals considered unlikely to be infected were assayed using both point-of-care LFAs from January 2024 through April 2025, and sensitivity and specificity estimates were calculated. RESULTS: The CrAg LFA (IMMY) had an estimated sensitivity of 95% (95% CI, 76.0% to 100%) and an estimated specificity of 100% (95% CI, 88.0% to 100%). The CrAg LFA (Dynamiker Biotechnology Co Ltd) had an estimated sensitivity of 100% (95% CI, 83.0% to 100%) and specificity of 20% (95% CI, 8.00% to 39.0%). CONCLUSIONS: The CrAg LFA (IMMY) is unequivocally superior to the CrAg LFA (Dynamiker Biotechnology Co Ltd) for the screening of cryptococcosis in dogs and cats due to its vastly superior specificity. CLINICAL RELEVANCE: The CrAg LFA (Dynamiker Biotechnology Co Ltd) in its present form should not be considered as a useful test to screen cats and dogs for cryptococcosis.