China review links human and canine leptospirosis risk

Version 2

A new Preventive Veterinary Medicine systematic review and meta-analysis examines human and canine leptospirosis in China through a One Health lens, synthesizing studies identified across six Chinese and international databases through November 11, 2025. The authors’ goal is straightforward: estimate prevalence patterns and identify associated factors in people and dogs sharing the same environmental risk landscape. That matters because leptospirosis remains a zoonotic disease with patchy visibility, even in places where it is formally reportable. (sciencedirect.com)

The backdrop is a long, uneven history of leptospirosis in China. National analyses show the disease has been legally classified as a Class B notifiable disease since 1955, and more recent epidemiologic work indicates that while incidence has stayed relatively low in recent years, transmission has remained concentrated in central and southern parts of the country. One study covering 2010 to 2022 found that 93.79% of reported human cases were concentrated in 10 provincial-level regions, including Sichuan, Yunnan, Guangdong, Hunan, Fujian, Zhejiang, Guangxi, Anhui, Jiangxi, and Guizhou. Broader historical analysis through 2022 similarly identified tropical and subtropical southern areas as persistent high-risk zones. (pmc.ncbi.nlm.nih.gov)

Against that backdrop, the new review is notable because it explicitly brings dogs into the same epidemiologic frame as people. The article notes that human cases have been reported from 29 of China’s 34 provincial-level administrative regions, underscoring wide distribution even if the burden is clustered. It also highlights the role of free-roaming and stray dog populations in maintaining and transmitting zoonotic pathogens in both urban and rural communities. That framing fits with CDC guidance that dogs can become infected through contact with contaminated water, wildlife, rodents, or infected urine, and that infected animals may shed the bacteria for weeks to months if not fully treated. (sciencedirect.com)

Recent canine data from China help explain why this combined human-dog view is useful. A 2025 study of dogs in the Yangtze River region found that the highest seropositivity for serogroup Canicola was detected along the river corridor, while Icterohaemorrhagiae had the broadest geographic distribution. The authors also reported seasonal associations, with higher risk in summer and autumn, and suggested that climate shifts and changing precipitation patterns could alter the geography of leptospirosis risk. Importantly for clinicians, that study raised the possibility that circulating serogroups may be shifting and argued that identifying local serogroups could support more targeted vaccine development and better surveillance. (pmc.ncbi.nlm.nih.gov)

There does not yet appear to be broad outside commentary tied specifically to this new meta-analysis, but the wider veterinary conversation has been moving in the same direction. AAHA summarized the 2023 ACVIM consensus update as recommending annual leptospirosis vaccination for all dogs starting at 12 weeks of age, regardless of breed, while noting WSAVA’s 2024 guidance is more region-specific, calling the vaccine core where canine leptospirosis is present, implicated serogroups are known, and appropriate vaccines are available. That’s relevant here because Chinese canine studies have questioned how well available vaccine serogroups match local epidemiology in some settings. (aaha.org)

Why it matters: For veterinary teams, the practical takeaway isn’t just that leptospirosis is zoonotic. It’s that dogs may be clinically important sentinels in places where human surveillance underestimates environmental exposure. Infected dogs can present with nonspecific signs, severe renal or hepatic disease, or no obvious signs at all, while still reflecting shared risk from rainfall, standing water, rodents, and urban wildlife interfaces. That makes case recognition, testing, infection-control counseling, and vaccine conversations part of a broader public health role. It also reinforces the need to think beyond a rural-only risk model when advising pet parents. (cdc.gov)

The review may also help push veterinary and public health stakeholders toward more integrated surveillance in China. If canine serology and molecular typing are incorporated more systematically, they could complement human reporting and improve local risk forecasting, especially in endemic southern provinces and in regions where rainfall patterns are changing. That would align closely with WOAH’s broader One Health framework, which emphasizes linked human, animal, and environmental surveillance for zoonotic threats. (pmc.ncbi.nlm.nih.gov)

What to watch: The next step is whether this paper leads to follow-on studies that quantify pooled prevalence estimates more clearly, standardize regional serogroup surveillance in dogs, and connect veterinary findings with China’s human notifiable disease reporting system. (sciencedirect.com)