Integrated Analysis of Human Hemorrhagic Fever with Renal Syndrome Cases and Rodent Hantavirus Surveillance in Zhejiang Province, China, 2025.

Hemorrhagic fever with renal syndrome (HFRS), caused by Seoul orthohantavirus (SEOV) and Hantaan orthohantavirus (HTNV), remains a neglected rodent-borne zoonosis with persistent residual spillover risk in low-incidence regions of China. This study assessed human HFRS occurrence and small-mammal hantavirus surveillance signals in small-mammal hosts across Zhejiang Province, China, in 2025. Reported human cases were obtained from the National Notifiable Disease Surveillance System, and animal host surveillance was conducted at five designated monitoring sites. A total of 107 HFRS cases were reported, occurring year-round with peaks in June and December and showing spatial heterogeneity, presenting a predominance of males, adults aged ≥40 years, and farmers. Animal host surveillance captured 617 small mammals (566 rodents and 51 shrews) from 15,457 valid trap-nights, with Apodemus agrarius (30.31%) and Rattus norvegicus (29.98%) as the dominant species. Sixteen animals were positive for hantavirus RNA and/or antibody, including 12 for hantavirus RNA and 6 antibody-positive animals; two were positive for both markers. Positive animals were detected in multiple species, including Niviventer confucianus, R. norvegicus, Rattus losea, A. agrarius, Suncus murinus, and Rattus tanezumi. Human incidence, small-mammal density, host species composition, and hantavirus-positive rates were not fully concordant across surveillance sites. Our findings reveal sustained cryptic orthohantavirus circulation in low-endemic Zhejiang, highlighting that integrated human-reservoir One Health surveillance is indispensable for precise spillover risk prediction and targeted zoonotic disease intervention.