# Hantavirus infections and small mammal diversity in Chile: No differences between protected and unprotected areas highlight the need for public health strategies

## TL;DR

A study in Chile found no difference in hantavirus infection rates or rodent diversity between protected and unprotected areas, suggesting other factors like climate or human behavior may influence virus spread more than protection status.

## Contribution

The study challenges the assumption that protected areas inherently reduce hantavirus risk and emphasizes the need for broader public health strategies.

## Key findings

- ANDV seroprevalence in O. longicaudatus was identical in protected and unprotected areas (9.5%).
- Ecological indices and community composition showed no significant differences between area types.
- Rényi profiles indicated marginally higher diversity in protected areas, but not significantly.

## Abstract

Zoonotic viruses, such as Orthohantavirus andesense (ANDV; the causative agent of hantavirus cardiopulmonary syndrome, HCPS), pose significant public health risks at the human-wildlife interface. Understanding their eco-epidemiological dynamics is critical for elucidating the interplay between reservoir hosts, environmental factors, and spillover to humans. In Chile, the long-tailed pygmy rice rat (Oligoryzomys longicaudatus) serves as the primary reservoir for ANDV. This study investigates whether protected areas (PA), which typically support higher biodiversity and stable ecosystems, exhibit lower ANDV seroprevalence compared to unprotected areas (UPA), where anthropogenic disturbances may alter host-pathogen dynamics.

Between 2001–2008, we conducted small mammal sampling across 22 sites (11 PA and 11 UPA) in natural landscapes of Chile. Seroprevalence of ANDV was assessed via strip immunoassay, while small mammal diversity was evaluated using standardized trapping protocols and diversity indices. We used similarity percentage analysis to identify species contributing to community dissimilarities and applied Renyi diversity profiles to compare small mammal diversity between area types.

We captured 627 small mammals (PA: 331, 14 species; UPA: 296, 10 species) across 12,898 trap-nights. Seroprevalence in O. longicaudatus was identical in PA and UPA (9.5%). No significant differences were found in the relative abundance or seropositivity of O. longicaudatus between area types. Ecological indices (Shannon-Wiener, Simpson, richness, evenness) and community composition (ANOSIM) also showed no significant differences. Rényi profiles indicated marginally higher diversity in PA, driven by greater richness and evenness.

These findings suggest that ecological factors, such as habitat type, climatic conditions, and/or human behavior, may play a more critical role in shaping viral prevalence than protection status alone. The study underscores the necessity for consistent public health interventions to mitigate the risk of hantavirus cardiopulmonary syndrome across all environments, particularly in regions where human activities intersect with natural habitats.

This study looked at how a virus that causes a serious disease in humans, spread by wild rodents, behaves in different natural environments in Chile. The study focused on O. longicaudatus, the main reservoir of Orthohantavirus andesense (ANDV), and compared its presence and infection levels in areas with environmental protection and those without. Over eight years, we studied small mammals in 22 locations across the country. Surprisingly, we found no major difference in the number of infected animals or in the diversity of small mammals between protected and unprotected areas. This challenges the idea that protected areas alone reduce the risk of people catching this virus. The results suggest that other factors—such as the landscape, climate, or human activities—may have a stronger influence on how the virus spreads in nature. This work highlights the importance of monitoring and public health actions in all geographic areas, not just those without protection, to reduce the risk of disease for people who live in or visit natural areas.