Molecular epidemiological investigation of a typhoid fever outbreak in South Africa, 2005: the relationship to a previous epidemic in 1993

• Published in: Epidemiology and infection Vol. 139; no. 8; pp. 1239 - 1245
• Main Authors: KEDDY, K. H., SOOKA, A., ISMAIL, H., SMITH, A. M., WEBER, I., LETSOALO, M. E., HARRIS, B. N.
• Format: Journal Article
• Language: English
• Published: Cambridge, UK Cambridge University Press 01.08.2011
• Subjects: Adolescent; Adult; Aged; Aged, 80 and over; Biological and medical sciences; Case-Control Studies; Child; Child, Preschool; Disease; Disease Outbreaks; Electrophoresis; Electrophoresis, Gel, Pulsed-Field; Epidemics; Epidemiology; Female; Fever; Fundamental and applied biological sciences. Psychology; Gastrointestinal infections; Gels; Gene loci; Genetic loci; Humans; Infections; Infectious diseases; Investigations; Laboratories; Low income groups; Male; Microbiology; Middle Aged; Molecular Epidemiology; Molecular Typing; Salmonella enterica; Salmonella typhi - classification; Salmonella typhi - genetics; Salmonella typhi - isolation & purification; South Africa - epidemiology; Typhoid; Typhoid fever; Typhoid Fever - epidemiology; Variables; Water supply; Young Adult; South Africa; Southern Africa; Africa; United States > US; Epidemic; typhoid fever; multiple-locus variable-number tandem repeat analysis (MLVA); pulsed-field gel electrophoresis (PFGE); South Africa; Infection; Bacteriosis; Molecular epidemiology; Digestive diseases; Salmonellosis; Typhoid
• ISSN: 0950-2688; 1469-4409
• DOI: 10.1017/S0950268810002207

In 2005, over 600 clinically diagnosed typhoid fever cases occurred in South Africa, where an outbreak had been previously described in 1993. Case-control and molecular investigations, including Salmonella enterica serovar Typhi (S. Typhi) isolates from that area from 1993, 2005 and later, were undertaken. Controls were significantly older than cases (P=0·003), possibly due to immunity from previous infection, and a significantly larger proportion had attended a gathering (P=0·035). Exposure to commercial food outlets and person-to-person transmission was not significant. Pulsed-field gel electrophoresis and multi-locus tandem repeat analysis revealed common clusters of S. Typhi strains identified in 1993 and 2005 as well as in 2007 and 2009. This outbreak probably occurred in a non-immune population due to faecally contaminated water. S. Typhi strains appeared to be related to strains from 1993; failure to address unsafe water may lead to further outbreaks in the area if the current population immunity wanes or is lost.