Page History

Background: Salmonella enterica subsp. enterica serovar Typhi is a serovar of the O:9 (D1) serogroup. S. Typhi causes typhoid fever, a life-threatening disease that is characterized by sustained fever as high as 103° to 104° F (39° to 40° C). In developed countries, this serovar is considered rare; however, in developing countries in Africa, Asia, and Latin America , it is among the top ten Salmonella serovars causing that caused disease in humans, where it . S. Typhi kills approx. 600.000 people annually. A number of projects have sequenced the genome of strains of S. Typhi strains; these studies have concluded that S. Typhi is a highly clonal serovar that emerged approx. 30,000--50,000 years ago. Horizontal In addition, studies have found that horizontal gene transfer had played plays an important role in the evolution S. Typhi, including this included the acquisition of plasmids encoding multiple antibiotic resistant genes in multidrug resistant strains.

Animal reservoir: S. Typhi is a human-restricted serovar.

Geographical distribution: S. Typhi is widely distributed; however, the prevalence of this serovar varies considerable. In developed countries (U.S., Canada, Europe), S. Typhi isolations correspond to less than 1% of all Salmonella serovars isolated from humans. In developing countries, S. Typhi isolations correspond to approxup to. 30% of all Salmonella isolated in some countries in Latin America and Asia.

Outbreaks: Salmonella Typhi has caused multiple outbreaks and sporadic cases, including outbreaks in the U.S. and Europe. In developing countries with endemic presence of typhoidal Salmonella, outbreaks are mostly undetected. On large outbreak (5,963 cases), was reported in Nepal.

...