Identification of Novel Bartonella washoensis Sequence Type 22 in Marmota himalayana — Jiuquan City, Gansu Province, China, 2021–2022

WHAT IS ALREADY KNOWN ABOUT THIS TOPIC? The prevalence of rodent-adapted Bartonella species has been increasing significantly. However, the specific Bartonella species carried by Marmota himalayana (M. himalayana), a large rodent species, and the potential risk it poses to human populations remain unknown. WHAT IS ADDED BY THIS REPORT? Bartonella washoensis (B. washoensis), associated with human endocarditis, was initially identified in M. himalayana, exhibiting a detection rate of approximately one-third and demonstrating a predilection for the heart and lungs. The discovery of the novel Sequence Type 22 has expanded both the isolation source and genetic lineage of B. washoensis. WHAT ARE THE IMPLICATIONS FOR PUBLIC HEALTH PRACTICE? Individuals residing within the M. himalayana plague focus are at an elevated risk for B. washoensis infection. Consequently, there is a pressing need for public health warnings and efficient clinical case identification in this population.