Salmonella: A Worldwide Problem

According to the European Commission and the World Organization for Animal Health, 60% of human pathogens are of animal origin.¹ This includes Salmonella. 

The threat of Salmonella infections has existed for more than a century, as it is one of the most widely spread foodborne diseases, infecting millions of people and killing thousands worldwide every year. 

In foods, Salmonella is most frequently found in eggs and raw meat from pigs, turkeys and chickens.³ Although there are many serovars or types of Salmonella, the two most common types responsible for human disease are also the most common types among poultry. This means that poultry meat and eggs are in fact the main source of contamination.⁴ 

The presence of Salmonella within a flock varies and can be influenced by a variety of factors. Vaccination schemes and the standard of bioprotection procedures, including rodent control, hygiene, housing, ventilation and feeding/watering systems, all have a role to play in Salmonella contamination and control.⁵ 

The Two Types of Salmonella

Many types of Salmonella serotypes exist, but Salmonella Typhimurium (ST) and Salmonella Enteritidis (SE) are the two most important serotypes with regard to human health and food safety. These two types of Salmonella are responsible for over 60% of outbreaks worldwide.¹

Salmonella Enteritidis (SE)

SE is the most common type of Salmonella. SE can affect the yolks of seemingly healthy chickens and sicken consumers who eat raw or undercooked eggs.⁶ In the EU, SE accounts for approximately 49% of human Salmonella cases.⁷

Salmonella Typhimurium (ST)

ST is one of the most important serotypes for quinolone resistance.⁸ In the EU, ST accounts for approximately 21% of human Salmonella cases.⁷

Salmonella can be transmitted vertically from parent stock to offspring, or horizontally from the environment to birds.

No matter the type, all Salmonella serovars can contaminate eggs externally and can also penetrate the shell and membrane.⁹ Some Salmonella serovars, such as SE and ST, are also found in the egg contents.⁹

Salmonella's Role in Antimicrobial Resistance

Salmonella is a high-priority pathogen for antibiotic research and development because the emergence of resistant serotypes can affect the food chain as well as human health. Salmonella Typhimurium is of particular concern and is considered an emerging threat for the poultry industry due to its multi-drug resistance.^{10, 11}

Addressing global antimicrobial resistance (AMR) concerns from foodborne pathogens, including Salmonella, is the responsibility of everyone along the food chain. Responsible use guidelines for AMR, including vaccination strategies, can improve Salmonella prevention in poultry and egg production. It's therefore imperative that poultry producers implement an effective vaccination program as part of their holistic approach to Salmonella control.