Feline Leukemia Virus and Feline Immunodeficiency Virus in Domestic and Free-Roaming Cats: A Systematic Review and Meta-Analysis of North American Prevalence, Risk Factors, and Diagnostic Considerations, 1987–2024

Feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV) are important retroviral pathogens affecting domestic and free-roaming cats worldwide. This systematic review and meta-analysis synthesized prevalence, risk factors, diagnostic considerations, and epidemiological trends in North America from 1987 to 2024. Following the PRISMA framework, studies from the United States and Canada were evaluated using data from 285,080 cats for FIV and 183,296 cats for FeLV. Pooled prevalence was 4.02% (95% CI: 3.60–4.49%) for FIV and 3.57% (95% CI: 3.13–4.07%) for FeLV, with substantial heterogeneity among studies. Older age, male sex, intact male status, outdoor access, poor health, and feral or shelter status were associated with increased infection prevalence. Prevalence remained relatively stable overall but varied geographically and across population types. Diagnostic limitations, particularly detection of regressive FeLV infection, may influence prevalence estimates. These findings support integrated surveillance, improved diagnostic strategies, vaccination, and targeted population management.