The Amazon tropical rainforest has the most dense and diverse ecosystem worldwide. A few studies have addressed rodent-borne diseases as potential hazards to humans in this region. Methods: A retrospective survey was conducted using enzymelinked immunosorbent assay for detecting mammarenavirus and orthohantavirus antibodies in 206 samples collected from rural settlers of the Brazilian Western Amazonian region. Results: Six (2.91%) individuals in the age group of 16 to 36 years were found to possess antibodies against mammarenavirus. Conclusion: Evidence of previous exposure to mammarenavirus in the rural population points to its silent circulation in this region.