Observed reduction in false measles IgM positivity using an ELISA kit containing RF absorbent

Area of Science:

• Immunology
• Infectious Disease Diagnostics
• Epidemiology

Background:

• Measles IgM ELISA assays can yield false-positive results, particularly in low-prevalence settings.
• High false-positive rates compromise the accuracy of measles surveillance and outbreak investigations.

Purpose of the Study:

• To evaluate the efficacy of a Rheumatoid Factor (RF)-absorbent ELISA assay in reducing false-positive measles IgM results.
• To assess the impact of RF-blocking on diagnostic specificity in measles surveillance.

Main Methods:

• Retesting of initially reactive measles IgM samples using an RF-absorbent ELISA assay.
• Quantification of the reduction in positive or borderline results after RF absorption.

Main Results:

• Out of 76 initially reactive samples, only 7 remained positive or borderline after RF absorption.
• A 91% reduction in false-positive measles IgM results was observed.

Conclusions:

• RF-absorbent ELISA assays are effective in improving the specificity of measles IgM testing.
• Implementing RF-blocking diagnostics enhances the accuracy of measles surveillance, especially in low-prevalence populations.