Molecular Epidemiology of Salmonella Serovars in the Poultry-Human Interface in Kano and Kaduna States

Salmonella enterica serovars circulating between poultry farms and human populations represent a major public health challenge in northern Nigeria, yet molecular epidemiological data remain scarce. This study investigated the molecular epidemiology of Salmonella serovars at the poultry-human interface across Kano and Kaduna States, North West Nigeria. Samples were collected from 300 broiler chickens at slaughter, 60 poultry farm workers, and 40 patients with laboratory-confirmed Salmonella gastroenteritis. Isolates were characterized using standard biochemical methods, serotyped using polyvalent O and H antisera, and subjected to molecular typing by pulsed-field gel electrophoresis. Antimicrobial susceptibility profiles were determined by broth microdilution. A total of 112 Salmonella isolates were recovered. Salmonella Kentucky and Salmonella Typhimurium were the dominant serovars in poultry, and matching pulsotypes were identified in both farm workers and patient isolates, providing genetic evidence of zoonotic transmission. Multi-drug resistance was observed in 58.9% of isolates, with fluoroquinolone resistance detected in 21.4%. Identical resistance gene profiles in poultry and human isolates suggested shared transmission pathways. The study demonstrates the utility of molecular typing in tracing Salmonella transmission at the poultry-human interface and concludes that coordinated surveillance integrating both sectors is essential. Improved farm biosecurity, restriction of fluoroquinolone use in poultry, and integrated One Health surveillance are recommended. Keywords: Salmonella, molecular epidemiology, poultry, zoonosis, antimicrobial resistance