Viral pathogens in urban rats: A one health systematic review of global surveillance evidence.

BACKGROUND

Commensal rats (Rattus norvegicus and Rattus rattus) thrive in urban environments worldwide, where they live near humans and may act as reservoirs for viral pathogens of public health relevance. Although rats are increasingly recognised as sentinels of urban environmental health, the diversity and distribution of viral infections circulating in urban rat populations remain incompletely characterised within a One Health framework.

OBJECTIVES

This systematic review synthesises global evidence on viral pathogens detected in urban rats, focusing on rat hepatitis E virus/Rocahepevirus ratti and human-associated hepatitis E virus/Paslahepevirus balayani where distinguishable, Seoul virus (SEOV), SARS-CoV-2, and additional viral taxa identified through targeted surveillance or, in rare cases, metagenomic approaches.

METHODS

Following PRISMA 2020 guidelines, five electronic databases were searched for primary studies reporting viral detection in urban Rattus spp. Eligible studies underwent screening, structured data extraction and quality appraisal. Viral prevalence was summarised descriptively by pathogen and geographic region.

RESULTS

A total of 70 studies met the inclusion criteria, spanning Europe, Asia, North America, South America and the Caribbean. HEV and SEOV were the most frequently reported viruses, with prevalence varying widely between regions. HEV prevalence ranged from low levels in parts of Europe and Asia to high levels in North America. SEOV was detected across all regions, with particularly high prevalence in parts of Asia and the Americas. SARS-CoV-2 was not detected in European rats but was reported at low to moderate prevalence in the Americas. Numerous additional viral pathogens were identified.

CONCLUSIONS

Urban rats globally harbour diverse viral communities, including pathogens with zoonotic potential. Surveillance remains uneven and methodologically heterogeneous. Integrating rat biomonitoring into coordinated One Health surveillance systems is critical to strengthen early warning capacity and mitigate zoonotic risk.