<i>Salmonella enterica</i> Serovar Infantis in Broiler Chickens: A Systematic Review and Meta-Analysis.

Abstract

<i>Salmonella enterica</i> subsp. <i>enterica</i> serovar Infantis poses a growing threat to public health, due to its increasing prevalence worldwide and its association with high levels of antimicrobial resistance. Among livestock, <i>S.</i> Infantis is especially isolated from broilers. Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, a systematic review was conducted by searching in three databases (Web of Science, Scopus, and PubMed) for English-language studies (1957-2023) that reported the prevalence of <i>S.</i> Infantis in broiler farms. Eligible studies included epidemiological investigations conducted in broiler chickens by sampling the house environment (flock-level prevalence) or the birds (individual-level prevalence). A random-effect model was applied to calculate <i>S.</i> Infantis pooled prevalence estimates with 95% confidence intervals (CIs). Furthermore, to assess between-study heterogeneity, the inconsistency index statistic (I²) was calculated. Among 537 studies retrieved, a total of 9 studies reporting flock-level prevalence of <i>S.</i> Infantis and 4 reporting individual-level prevalence were retained for analysis. The flock-level pooled prevalence was estimated to be 9% (95% CI: 1-26%) and a high between-study heterogeneity was found (I² = 99%, <i>p</i> < 0.01). Concerning individual-level prevalence, a meta-analysis was not performed due to the scarcity of eligible studies. The data presented underscore the significant occurrence of <i>S.</i> Infantis in broilers at the farm level. By summarizing the existing literature, this work provides useful insights for conducting future surveys of <i>Salmonella</i> spp. in live broiler chickens as a preliminary step for developing more efficient control strategies.