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S. typhi

CAS Number:
Synonyms: Bacillus typhosus, Eberthella typhosa, Salmonella enterica serovar Typhi, Salmonella typhosa
Contaminant Type: Microbial

Salmonella typhi (S. typhi) is a bacterium that causes typhoid fever in humans [965]; illnesses are typically caused by ingesting contaminated food or water [953].

S. typhi is a facultative anaerobic, gram negative bacterium that belongs to the family Enterobacteriaceae and the genus Salmonella. The nomenclature and classification of salmonella genus have changed over the years [965]. The current classification of S. typhi is Salmonella enterica serovar typhi [965].

Contaminated water and food are the common sources of typhoid fever in endemic areas [965, 953]. Patients with typhoid fever (either acute or chronic) excrete large numbers of organisms and serve as the principal transmission sources. [965]

Although S. typhi is strictly adapted to humans, it can survive in the environment. It may survive in water or ice for many weeks [963]; some studies suggest that S. typhi can survive for days to a few weeks in groundwater, pond water, or seawater [967, 968]. Survival in sewage is usually less than a week [963]. The optimal growth temperature for S. typhi is 37 °C and it can be killed by a temperature of 60 °C for 15 minutes, and rapidly by boiling [965]. S. typhi is acid sensitive and will generally be killed at a pH level of less than 2.5 [969].

S. typhi is strictly adapted to humans and only causes illness in humans [965]. Typhoid fever is an acute systemic infection that can be fatal [953]. A similar disease, paratyphoid fever, is often discussed together with typhoid fever. Paratyphoid is caused by S. Paratyphi A, B and sometimes C, and is usually less severe than typhoid fever [953]. Typhoid and paratyphoid fevers are collectively referred to as enteric fevers [953]. Typical symptoms of typhoid fever include prolonged fever, headache, enlargement of the spleen, rose-colored spots on the abdominal surface, constipation, or diarrhea [953, 965].

Typhoid fever has been a severe epidemic human disease for centuries [963]. In the United States, improvements in sanitation, quality of water supplies, and food hygiene since the 1920s have dramatically decreased the prevalence of typhoid fever. For example, between 1990 and 1999, 420 cases and less than one death per year have been attributed to typhoid fever [966]. A large portion of infections is related to foreign travels [970, 971].

S. typhi is currently not regulated by USEPA in drinking water.

No occurrence data for S. typhi were found for source waters currently used for drinking water in the United States.

Date of Literature Search: August 2009

953 Virginia Bioinfomatics Institute ; 2009; Pathogen information (pathinfo); http://pathport.vbi.vt.edu/pathinfo/pathogens/enterica_Info.shtml; As posted on August 25, 2009. Virginia Bioinformatics Institute Blacksburg, VA 24061
963 Huckstep, R.L.; 1962; Epidemiology; Typhoid Fever and Other Salmonella Infections; Chapter 3. pp. 10 and 17 - 19. E. & S. Livingstone Ltd. Edinburgh and London.
965 Kim, A.Y., Goldberg, M.B., Rubin, R.H., Gorbach, S.L. (Ed.), Bartlett, J.G. (Ed.) and Blackflow, N.R. (Ed.); 2004; Salmonella Infections; Infectious Diseases; Chapter 68. pp. 618 - 620 and 623 - 625. Lippincott Williams & Wilkins, Philadelphia.
966 Groseclose, S.L., Hall, P.A., Knowles, C.M., Adams, D.A., Park, S., Perry, F., Sharp, P., Anderson, W.J., Snavely, K., Fagan, R.F., Aponte, J.J., Jones, G.F., Nitschke, D.A., Worsham, C.A., Glynn, M.K., Chang, M.H., Doyle, T. and Jajosky, R.A.; 2001; Summary of Notifiable Diseases, United States, 1999; Morbidity and Mortality Weekly Report; 48:53. pp. 86. Centers for Disease Control and Prevention, Department of Health and Human Services, Atlanta, GA.
967 Cho, J.C. and Kim, S.J.; 1999; Viable, but non-culturable, state of a green fluorescence protein-tagged environmental isolate of Salmonella typhi in groundwater and pond water; FEMS Microbiology Letters ; 170:1:257
968 Wait, D.A. and Sobsey, M.D.; 2001; Comparative survival of enteric viruses and bacteria in Atlantic ocean seawater; Wat. Sci. Tech.; 43:12:139
969 Gorden J. and Small P.L.; 1993; Acid resistance in enteric bacteria; Infect Immun. ; 61:1:364
970 Ryan, C.A., Hargrett-Bean, N.T. and Blake, P.A.; 1989; Salmonella typhi infections in the United States, 1975-1984: increasing role of foreign travel; Re. Infect. Dis.; 11:1:1
971 Lynch, M.F., Blanton, E.M., Bluens, S., Polyak, C., Vojdani, J., Stevenson, J., Medalla, F., Barzilay, E. Joyce, K., Barrett, T., Mintz, E.D.; 2009; Typhoid fever in the United States, 1999-2006; JAMA; 302:8:859

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