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Modified-live vaccines (MLVs) against paratyphoid Salmonella serotypes help reduce colonization and excretion of wild strains of the bacterium. The vaccines also lessen the impact of heterologous strains in young poultry, which have immature immune systems.

That’s the conclusion of a review paper from a number of industry experts, published in Avian Diseases.¹

Immune responses to Salmonella infection are complex, say the authors, but vaccination has become a key component of multi-step control programs.

Live vaccines have several advantages over killed vaccines, they say. These include surface antigens that provide cross-protection against different Salmonella serotypes such as Typhimurium, Enteritidis and Infantis, as well as the ability to generate cell-mediated immunity and stimulate production of antibodies to protect mucosal surfaces.

“A company doesn’t have just one Salmonella serovar. They’ll have multiple Salmonella serovars and so the real take home is that if I use a live Salmonella vaccine, I’m going to get protection against multiple Salmonella serovars,” Charles Hofacre, DVM, PhD, lead author of the review, told Poultry Health Today.

“Another main point is that using a live Salmonella vaccine in your young breeders is very important because it gives them protection and helps to prevent them from becoming colonized with some of these ‘bad guys’ that cause human illness,” said Hofacre, of the Southern Poultry Research Group, Inc.