Zoonotic salmonellosis: Which Salmonella serovar is the most common cause of zoonotic disease in humans across diverse animal reservoirs and food sources?

Introduction / Context:
Non-typhoidal Salmonella (NTS) infections are major zoonoses transmitted via contaminated animal products (poultry, eggs, meat, dairy) or direct animal contact. Among numerous serovars, a few dominate global human disease burden, making their recognition important for clinicians and public health.

Given Data / Assumptions:

• We are focusing on zoonotic, non-typhoidal Salmonella.
• Human infection typically results from foodborne exposure.
• Common serovars include Typhimurium and Enteritidis; regional variations occur.

Concept / Approach:
Historically and globally, Salmonella Typhimurium has been among the most frequently isolated serovars from human gastroenteritis with broad animal reservoirs. S. Enteritidis is also prominent (notably linked to eggs), but S. Typhimurium is widely cited as the commonest zoonotic serovar across species.

Step-by-Step Solution:
Identify the question focus: the single most common zoonotic serovar.Compare epidemiology: Typhimurium vs Enteritidis and others.Select the best-supported global “commonest” serovar: S. typhimurium.Confirm it aligns with multi-host reservoirs and frequent human isolation.

Verification / Alternative check:
Surveillance reports from multiple countries repeatedly list S. Typhimurium among the top serovars in human disease, reinforcing the choice.

Why Other Options Are Wrong:

• S. enteritidis: very common but often second to Typhimurium in many datasets.
• S. newport, S. Indiana: important regionally but less dominant globally.

Common Pitfalls:
Assuming regional spikes (e.g., egg-associated Enteritidis) define the global “commonest”; the question asks broadly across reservoirs.

Final Answer:
S typhimurium