title: Population-based study of the incidence of Shigella diarrhea and causative serotypes in Santiago, Chile.
abstract: BACKGROUND
  Shigella is an important cause of diarrheal disease in children in developing countries. The increasing prevalence of antibiotic-resistant strains has stimulated interest in the use of multivalent Shigella vaccines. Because Shigella vaccines under development are based on eliciting immunity to O antigens, monitoring the distribution of serotypes in defined target populations is critical. We initiated health center-based surveillance in a poor semirural community in Colina, Santiago (7489 children <60 months of age) to determine the age-specific incidence of Shigella disease and the responsible serotypes.
  
  
  RESULTS
  Surveillance was maintained at the 2 health centers during warm seasons (November 1 through April 30) for 4 successive years (1994 to 1998). Shigella was recovered from 54 of 243 cases of dysentery (22%) and from 215 of 3966 cases of nondysenteric diarrhea (5.4%) (P < 0.001). The peak mean annual incidence of shigellosis occurred among children 12 to 47 months of age (9.0 to 12.6 cases/10(3) children), although the incidence in infants (5.2/10(3)) and children 48 to 59 months of age (6.2/10(3)) was also substantial. During the 1995 through 1996 season, an age-matched healthy control was cultured for every child <60 months of age with diarrhea. Shigella isolation from cases (34 of 576, 5.9%) was >8-fold higher than controls (4 of 576, 0.7%) (P < 0.01). Four serotypes, Shigella sonnei (45%), Shigella flexneri 2b (19%), S. flexneri 2a (14%) and S. flexneri 6 (11%), accounted for 89% of all cases.
  
  
  CONCLUSIONS
  Shigella remains an important pediatric pathogen in Santiago. The serotype distribution from Colina, which closely resembles data from a population-based surveillance study in Santiago in the mid-1980s, demonstrates a remarkable degree of serotype stability in Santiago during a 15-year period.
authors.affiliation: Programa de Microbiología, ICBM, Facultad de Medicina, Campus Oriente, Universidad de Chile, Santiago.
authors.forename: V
authors.initials: V
authors.lastname: Prado
authors.forename: R
authors.initials: R
authors.lastname: Lagos
authors.forename: J P
authors.initials: JP
authors.lastname: Nataro
authors.forename: O
authors.initials: O
authors.lastname: San Martin
authors.forename: C
authors.initials: C
authors.lastname: Arellano
authors.forename: J Y
authors.initials: JY
authors.lastname: Wang
authors.forename: A A
authors.initials: AA
authors.lastname: Borczyk
authors.forename: M M
authors.initials: MM
authors.lastname: Levine
mesh_terms: D016022:Case-Control Studies; D002675:Child, Preschool; D002677:Chile / Q000453:epidemiology; D003967:Diarrhea / Q000382:microbiology; D003968:Diarrhea, Infantile / Q000453:epidemiology / Q000382:microbiology; D004405:Dysentery, Bacillary / Q000453:epidemiology* / Q000382:microbiology*; D006801:Humans; D015994:Incidence; D007223:Infant; D011159:Population Surveillance; D012703:Serotyping; D012760:Shigella / Q000145:classification* / Q000302:isolation & purification