# Eco-epidemiology of arbovirus infections among non-human primates in Southeastern Brazil

## TL;DR

This study explores arbovirus infections in non-human primates in Brazil, identifying new infection patterns and transmission routes that could inform public health strategies.

## Contribution

The study reports the first detection of SLEV in golden-handed tamarins and novel co-infections in specific primate species, suggesting alternative transmission routes.

## Key findings

- 30 out of 248 non-human primates were infected with orthoflaviviruses, revealing geographic hotspots.
- Zika virus and SLEV were detected in saliva and rectal swabs, suggesting non-vector transmission routes.
- Coinfections with ZIKV and DENV-3 in C. penicillata and ZIKV and SLEV in black howler monkeys were identified for the first time.

## Abstract

Orthoflaviviruses and alphaviruses are arboviruses responsible for human diseases in tropical and subtropical countries. We aimed to detect infections with arboviruses and to evaluate the ecological patterns related to these infections among non-human primates (NHPs) in southeastern Brazil. Of the 248 molecularly screened NHPs, 30 were infected with orthoflaviviruses, which highlighted hotspots of arboviruses. We identified genome fragments of orthoflaviviruses Orthoflavivirus denguei 1 (DENV-1), 2 (DENV-2) and 3 (DENV-3), Orthoflavivirus louisense (SLEV), Orthoflavivirus zikaense (ZIKV), and Orthoflavivirus flavi (YFV). No alphaviruses were detected. Amid a human outbreak of YFV, black-tufted marmoset (Callithrix penicillata) was identified as being infected. SLEV and ZIKV were found in saliva samples and rectal swabs obtained from NHPs, a potential route for non-vector transmission of these viruses. This is the first report of infection with SLEV in the golden-handed tamarin (Saguinus midas) as well as coinfections with ZIKV and DENV-3 in C. penicillata and with ZIKV and SLEV in black howler monkey (Alouatta caraya). The isolation of ZIKV and SLEV from the saliva of NHPs may suggest an alternative mechanism for the maintenance of these viruses within NHP communities, in addition to the conventional transmission by mosquitoes. These findings are fundamental to support public health policy decisions and to foster ongoing eco-epidemiological surveillance of arboviruses in the context of the human-animal interface.

Arboviruses pose a significant public health threat worldwide and underlie major infectious disease outbreaks. These viruses are transmitted by complex dynamics, which are influenced by various factors, including viral, ecological, and epidemiological factors, vectors, and human movement. However, an incomplete understanding of how natural hosts (especially mammals such as non-human primates (NHPs)) and certain orthoflaviviruses and alphaviruses are intricately related prevents outbreaks from being predicted and effective public health interventions from being implemented. In this study, we aimed to improve our understanding of host-vector dynamics by integrating knowledge from diverse disciplines, including virology, epidemiology, and ecological modeling. We were able to identify an undocumented orthoflavivirus in NHPs, Orthoflavivirus louisense (SLEV), and to correlate infections with geographical hotspots and specific NHP species. Employing a One Health eco-epidemiological approach was more suitable for surveilling orthoflavivirus outbreaks and could allow cost-effective public health interventions to be implemented through targeted mitigation strategies. Furthermore, we gained valuable insights into how orthoflaviviruses and less explored hosts are related, which is crucial knowledge for arbovirus surveillance and preservation of mammalian biodiversity worldwide, particularly in a climate change scenario.