RESUMEN
BACKGROUND: Human infections by Mayaro virus (MAYV) occur by insect bites upon exposure to rural or sylvatic areas. Information regarding MAYV transmission is limited due to a lack of commercial diagnostic assays and diagnostic confusion on account of similarities of clinical signs with other co-circulating arboviral diseases. METHODS: A serological survey of MAYV and Chikunguya virus (CHIKV) antibodies was performed by ELISA. Between 2017 and 2018, 5608 blood donor samples were tested. RESULTS: Specific IgM and IgG antibodies to MAYV were detected respectively in 36 and 11 samples, indicating a total seroprevalence of approximately 0.83%. Neutralization activity was observed in two IgG positive sera. Additionally, eight distinct samples had IgM antibodies to CHIKV alone. CONCLUSIONS: Our data suggest previously unreported circulation of MAYV in São Carlos city, from southeastern Brazil.