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Outbreaks: Salmonella Typhi has caused multiple outbreaks in the U.S. and Europe. In developing countries with endemic presence of typhoidal Salmonella, outbreaks are mostly undetected. On large outbreak (with 5,963 cases), was reported in Nepal. However, in developing countries, outbreaks are mostly undetected.
Year | Location | Associated source | Number of cases |
2010 | US-multistate | Frozen mamey fruit pulp | 9 |
2002 | Nepal | Drinking water | 5963 |
2000 | US-New York | Food handler | 7 |
1999 | US-Florida | Frozen mamey fruit pulp (imported) | 16 |
1998 | France | Chicken rice | 27 |
1997 | France | Pork, food handler | 26 |
Relevant genetic characteristics: Whole genome sequences for 20 strains of S. Typhi have been deposited at GenBank as of October, 2013. Genomic characteristics of the sequenced S. Typhi include (i) a genome size ranging from 4.54 to 5.03 Mb, (ii) a mol G+C% of approx. 52, and (iii) 4,419 to 5,336 predicted genes. Plasmids and prophages have been identified in S. Typhi. For example, a resistant plasmid of 218 kb and seven prophages were detected in S. Typhi CT18. Up to ten 15 Salmonella pathogenicity islands (SPIs) have been detected in S. Typhi, these include SPI-1 to 7, 9, 11 to 13, and 15 to 18. Comparative genomics and phylogenetic analyses have shown that S. Typhi (i) has had a monophyletic origin approx. 50,000 years ago (ii) has suffered reductive evolution (approx. 5% of the genome 200 genes are functionally inactive), (iii) belongs to clade A, according to den Bakker et al. (2011) classification, and (iv) has 349 gene families unique to this serovar.
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