(Mahendra Kothary) mkothary@cfsan.fda.gov – Division of Virulence Assessment (HFS327) Center for Food Safety and Applied Nutrition, US FDA. “The human infective dose varies depending on the serovar of the organism. Results from the volunteer studies indicated that the infective dose for various serovars was 105 – 1010 organisms. The attack rate depended on the serovar of the organism and ranged from about 16-50%. However, data from outbreaks suggest that infection dose may be as high as 107 – 109 organisms. Various authors of these studies suggested that the high fat and protein content of the food vehicle involved in the outbreaks may have played an important role in protecting the organism from gastric acidity. When present in dry feed, Salmonella can survive for more than 1 year, and even low numbers may be significant because for some strains, 1 cell per g is sufficient to colonize young chicks (157).
