ABSTRACT
In 1942, there were approximately 5500 isolates of Salmonella typhi in the US. That number of isolates has been reduced to below 500 currently. On the other hand, other Salmonella serotypes have been isolated at an increasing rate, from below 500 in 1942 to between 10,000 and 60,000 isolates in 1985. Between 1975 and 1987, the Centers for Disease Control (CDC) in Atlanta determined that there had been a severalfold increase in the numbers of infections caused by S. enteritidis in several states in the Northeastern section of the US. In over 70% of the cases of infection noted, the source of the infection was traced to contaminated eggs, much as in the case of the contaminated ice cream product in the New York outbreaks. After much study these outbreaks of salmonellosis from carefully inspected and graded eggs were determined to be due to passage of the pathogen from the hen to the egg by transovarian transmission.
