Public Health Aspects of Salmonella Infections

In 1880, Karl Joseph Eberth described a bacillus that he suspected to be the cause of typhoid fever (Eberth, 1880). In 1884, the pathologist Georg Theodor August Gaffky confi rmed Eberth’s fi ndings, and the organism was named Gaffky-Eberth bacillus. At that time, it was also known that bacteria similar to Salmonella serovar Typhi could cause enteric disease in humans and farm animals. This was proved when Salmon and Smith reported the isolation of the bacteria responsible for ‘hog cholera’ or ‘swine fever’ in 1885. The name Salmonella was subsequently adopted in honour of Salmon, an American veterinary surgeon. In the early to mid-20th century there were many pioneering studies into the identifi cation and differentiation of Salmonella. The schemes that were developed made use of the fact that, although Salmonella show considerable antigenic diversity, they elicit two principal antibody reactions in infected animals. Thus antibodies are produced against cell-surface or somatic O antigens and fl agella or H antigens. In 1929, White developed a typing scheme based on this antigenic variation, which was later modifi ed by Kauffmann. This work enabled the differentiation of Salmonella into serovars. In 1934, the fi rst Kauffmann-White scheme containing 44 serovars was published by Kauffmann and the Salmonella Subcommittee (Kelterborn, 1967). Later, biochemical methods were introduced into the scheme to better identify the diverse characteristics of Salmonella species and subspecies. In the following years, supplements describing novel serovars of different subspecies had been published by the WHO Collaborating Centre for Reference and Research on Salmonella under the leadership of Le Minor. In recognition of the importance of the work by Le Minor in the 1970s and 1980s, the scheme was renamed the WhiteKauffmann-Le Minor scheme. Two species had been classifi ed within the genus Salmonella: S. enterica (grouped in six subspecies) and S. bongori (former subsp. V, with only 23 serovars). The vast majority of serovars (1547) belong to S. enterica subsp. enterica. The last supplement (no. 47) was edited in 2010 by Weill and specifi es 2610 Salmonella serovars. To date, the WhiteKauffmann-Le Minor scheme is the benchmark for Salmonella typing worldwide (Guibourdenche et al., 2010). Today the scientifi cally correct term for the bacillus that causes typhoid fever is Salmonella enterica subsp. enterica serovar Typhi or short S. Typhi.