title: Molecular epidemiological investigation of a typhoid fever outbreak in South Africa, 2005: the relationship to a previous epidemic in 1993.
abstract: 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.
authors.affiliation: Enteric Diseases Reference Unit, National Institute for Communicable Diseases and Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa. karenk@nicd.ac.za
authors.forename: K H
authors.initials: KH
authors.lastname: Keddy
authors.forename: A
authors.initials: A
authors.lastname: Sooka
authors.forename: H
authors.initials: H
authors.lastname: Ismail
authors.forename: A M
authors.initials: AM
authors.lastname: Smith
authors.forename: I
authors.initials: I
authors.lastname: Weber
authors.forename: M E
authors.initials: ME
authors.lastname: Letsoalo
authors.forename: B N
authors.initials: BN
authors.lastname: Harris
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D004196:Disease Outbreaks; D016521:Electrophoresis, Gel, Pulsed-Field; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017720:Molecular Epidemiology; D058889:Molecular Typing; D012485:Salmonella typhi / Q000145:classification* / Q000235:genetics* / Q000302:isolation & purification; D013019:South Africa / Q000453:epidemiology; D014435:Typhoid Fever / Q000453:epidemiology*; D055815:Young Adult