Salmonella Pullorum: Now You See Me, Now You Don’t — The Paradox of Detection in Chicken Infection Models

Abstract

Salmonella enterica serovar Pullorum (S Pullorum) presents a persistent paradox in avian infection biology: chickens often display pathological, immunological, and serological evidence of infection while viable bacteria remain undetectable by conventional culture. This “now you see me, now you don’t” phenomenon reflects biological adaptation rather than experimental failure. As a host-restricted pathogen, S Pullorum has evolved toward intracellular persistence, reduced inflammatory stimulation, and limited shedding, enabling long-term survival at levels below routine detection thresholds. Consequently, culture negativity does not necessarily indicate bacterial clearance. Reliance on bacteriological recovery alone may therefore lead to misinterpretation of infection dynamics in experimental models and underestimation of silent reservoirs in surveillance systems. Recognizing the disconnect between detectability and persistence is essential for accurate interpretation of host–pathogen interactions and for designing diagnostic and surveillance strategies suited to stealth, host-adapted bacterial pathogens.