Hantavirus RNA Detection in Small Mammals and Spatial Comparison with Reported Human HFRS Cases in West Kazakhstan Region, 2025

Hemorrhagic fever with renal syndrome (HFRS) is a zoonotic disease associated with orthohantaviruses maintained in natural rodent hosts. This study assessed the detection and spatial distribution of hantavirus RNA among small mammals in the West Kazakhstan Region in 2025 and compared rodent surveillance findings with human HFRS occurrence. An observational cross-sectional analytical study was conducted in July and September 2025 in four districts. A total of 343 small mammals were captured and morphologically identified. Lung tissue samples from 329 animals collected in September were examined in 123 pooled testing units, whereas 14 animals collected in July were tested individually. Thus, 137 testing units representing 343 animals were evaluated by real-time and conventional RT-PCR. The minimum infection rate (MIR) was calculated as a descriptive minimum estimate, and a pooled-testing likelihood model was used to account for variation in testing-unit size. Hantavirus RNA was detected in 47/137 testing units, including 45 positive pooled units and two individually positive specimens. Based on 343 individual animals, the descriptive MIR was 13.7%. The model-based individual-level infection probability was estimated at 18.0% (95% profile-likelihood CI: 13.5–23.1%). Positive testing units were observed among the Ural field mouse (Apodemus uralensis), bank vole (Myodes glareolus), and common vole (Microtus arvalis). At the district level, the descriptive MIR ranged from 11.6% in Burlinsky to 19.0% in Chingirlauisky. Sampling sites overlapped spatially with settlements reporting human HFRS cases, including Utvinka, Daryinsk, and Rubezhinskoye; however, spatial coincidence does not establish direct transmission.