Health Status and Pathogen Surveillance in Free-Ranging Nancy Ma’s Night Monkeys (Aotus nancymaae) along the Amazonian Tri-Border Region

Nancy Ma’s night monkeys (Aotus nancymaae) are significantly impacted by illegal trafficking along the tri-border region between Peru, Colombia, and Brazil. Night monkeys previously used for biomedical research have been released into natural forests along the tri-border region posing a health and conservation threat to local wild monkey populations. We evaluated the health of 55 adult night monkeys during two sampling periods (2018 and 2023) along the tri-border region through clinical evaluation, determination of ectoparasite presence, and through surveillance via PCR of oral swabs and blood samples followed by Sanger sequencing for herpesviruses, orthoflaviviruses, and Mycobacterium tuberculosis complex. Ectoparasites were more commonly found during the dry season (odds ratio=4.18, 95% confidence interval [1.36, 13.99], P=0.015). The presence of herpesvirus and flavivirus was 48.6% (18/37) and 1.8% (1/55), respectively. Sanger sequencing identified two distinct herpesviruses (Aotus nancymaae cytomegalovirus 1 and Aotus nancymaae lymphocryptovirus 1) and one flavivirus (86.18% identity to the Psorophora flavivirus, part of the insect-specific flavivirus lineage II group in South America). Tuberculosis-causing mycobacteria was not detected. Our findings provide molecular evidence that orthoflaviviruses and herpesviruses are detectable in free-ranging night monkeys in the tri-border region, underscoring the importance of future studies to investigate infection dynamics and the prevalence of potential zoonotic pathogens associated with this primate species within the Amazon Basin.