J. Drexel1; J. Liu1; M. Beall2; M. Lappin3; R. Chandrashekar1
Feline leukemia virus (FeLV) is a highly contagious virus that can cause life-threatening diseases in cats if infected. In practice, rapid antigen tests are commonly used, and often it is the only mechanism to identify infected cats. The accuracy of rapid tests is of paramount importance.
To compare the performance of three in-clinic rapid tests for FeLV antigen: SNAP® Feline Triple® (IDEXX), Anigen® FIV/FeLV test (BioNote), Speed Duo® FeLV/FIV test (Virbac).
Serum or plasma samples were collected from those submitted for feline retroviral testing at IDEXX Reference Laboratories. All samples were screened using an independent laboratory ELISA assay, ViraCHEK® FeLV (Zoetis), for the presence or absence of FeLV antigen. A total of 84 positive and 101 negative samples were included in this study. Samples were blinded and randomized for testing with in-clinic rapid tests, according to manufacturers’ instructions.
Compared to ViraCHEK®, percent agreements for positive and negative samples were 97.6%/100% (SNAP®), 66.7%/97.0% (Anigen®), and 51.2%/99.0% (Speed Duo®).
These findings suggest a lower sensitivity for the Anigen® and Speed Duo® tests, based on the ViraCHEK® results. Consistent with a recently published study, this study also found a lower specificity for the Anigen® test, which would indicate a proportion of the Anigen® test positive results could be false positive given very low prevalence for FeLV. Both false negative and false positive test results for FeLV could lead to significant clinical issues.