Abstract
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 descriptive-analytical study was conducted in August–September 2025 in four districts. A total of 343 small mammals were captured and morphologically identified. Lung tissues were tested using 123 pooled testing units, while 14 specimens were tested individually during the same surveillance campaign. 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, corresponding to a descriptive MIR of 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 Apodemus uralensis, Myodes glareolus, and 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.