Salmonella Food Poisoning
What is Salmonella and how does it cause food poisoning?
Salmonella is a bacterium that causes one of the most common enteric (intestinal) infections in the United States – salmonellosis.  It has long been said that, in 1885, pioneering American veterinary scientist, Daniel E. Salmon, discovered the first strain of Salmonella. Actually, Theobald Smith, research-assistant to Dr. Salmon, discovered the first strain of Salmonella–Salmonella cholerae suis.  But, being the person in charge, Dr. Salmon received credit for the discovery.  In any case, today the number of known strains of the bacteria totals over two thousand. [5, 6]
The term Salmonella refers to a group or family of bacteria that variously cause illness in humans. Salmonella serotype typhimurium and Salmonella serotype Enteritidis are the most common in the United States. [5, 15, 26] Salmonella javiana is the fifth most common serotype in the United States and accounted for 3.4% of Salmonella isolates reported to the CDC during 2002.  According to one study,
During the 1980s, S. Enteritidis emerged as an important cause of human illness in the United States. In 1976, the incidence of S.Enteritidis was 0.55 per 100,000 population and represented only 5% of all Salmonella isolates. By 1985, this proportion reached 10%, and the rate increased to 2.4 per 100,000 population. During the same time, total Salmonella infection rates rose from 10.7 per 100,000 in 1976 to 24.3 in 1985. The highest rates of S. Enteritidis were seen in the Northeast, although rates in the western region also increased during this time.
The number of outbreaks of S. Enteritidis infection also increased during the 1980s, particularly in the northeastern United States. Laboratory subtyping of S. Enteritidis isolates from outbreaks indicated that phage types (PT) 8 and 13a were the most common phage types in the United States. Although PT4 was common in Europe, where it coincided with a large increase in S. Enteritidis infections, it was seen in the United States only among persons with a history of foreign travel. 
Of the Salmonella outbreaks that occurred from 1985 through 1999, “[f]ive hundred twenty-two (62%) outbreaks of S. Enteritidis infection were associated with food prepared at commercial food establishments (restaurants, caterers, delicatessens, bakeries, cafeteria, or market).”