Impact of serum heat inactivation on the performance of the microscopic agglutination test in human leptospirosis diagnosis

The clinical diagnosis of human leptospirosis is challenging owing to the non-specific nature of its symptoms, making laboratory confirmation essential. The microscopic agglutination test (MAT), recommended by the World Health Organisation as the reference serological method for diagnosing leptospirosis, requires ongoing efforts towards optimisation. The present study evaluated the impact of thermal inactivation of serum samples on MAT performance for the diagnosis of human leptospirosis. Thermal inactivation did not compromise antibody detection capacity. Discrepancies observed between inactivated and non-inactivated samples (8.4%; n = 11/131) were limited to minor titer variations and, in most cases, did not alter the study-defined case interpretation or the identification of the infecting serogroup. Furthermore, inactivation improved the clarity of agglutination reactions in some samples (n = 5).