Salmonella is a bacterium that causes one of the most common enteric (intestinal) infections in the United States, salmonellosis. In 1885, pioneering American veterinary scientist Daniel E. Salmon is said to have discovered the first strain of Salmonella. However, Theobald Smith, research assistant to Dr. Salmon, likely actually discovered the first strain, Salmonella cholerae suis, then his boss took credit for the discovery. Today, there are over two thousand known strains of Salmonella.
The term Salmonella refers to a group or family of bacteria that cause various illnesses in humans. Salmonella serotype typhimurium and Salmonella serotype enteritidis are the most common in the U.S. Salmonella javiana is the fifth most common serotype in the U.S. and accounted for 3.4 percent of Salmonella isolates reported to the CDC in 2002,. according to one study.
During the 1980s, S. Enteritidis emerged as an important cause of human illness in the U.S. In 1976, the incidence of S. Enteritidis was 0.55 per 100,000 people and represented only 5 percent of all Salmonella isolates. By 1985, this proportion reached 10 percent, and the rate increased to 2.4 per 100,000 people. During the same time, total Salmonella infection rates rose from 10.7 per 100,000 in 1976 to 24.3 per 100,000 in 1985. The highest rates of S. Enteritidis were seen in the Northeastern U.S., although rates in the west also increased during this time.
The number of outbreaks of S. Enteritidis infection also increased during the 1980s, particularly in the Northeastern U.S. Laboratory subtyping of S. Enteritidis isolates from outbreaks indicated that phage types (PT) 8 and 13a were the most common phage types in the U.S. Although PT4 was common in Europe, where it coincided with a large increase in S. Enteritidis infections, it was seen in the U.S. only among persons with a history of foreign travel. [26]
Of the Salmonella outbreaks that occurred from 1985 to 1999, “Five hundred twenty-two (62 percent) of outbreaks of S. Enteritidis infection were associated with food prepared at commercial food establishments (restaurants, caterers, delicatessens, bakeries, cafeterias, or markets).”