title: A systematic review of ETEC epidemiology focusing on colonization factor and toxin expression.
abstract: BACKGROUND
  Vaccine development for enterotoxigenic Escherichia coli (ETEC) is dependent on in-depth understanding of toxin and colonization factor (CF) distribution. We sought to describe ETEC epidemiology across regions and populations, focusing on CF and toxin prevalence.
  
  
  METHODS
  We conducted a systematic review of the published literature, including studies reporting data on ETEC CF and toxin distributions among those with ETEC infection. Point estimates and confidence intervals were calculated using random effects models.
  
  
  RESULTS
  Data on 17,205 ETEC isolates were abstracted from 136 included studies. Approximately half of the studies (49%) involved endemic populations, and an additional 17% involved only travel populations. Globally, 60% of isolates expressed LT either alone (27%) or in combination with ST (33%). CFA/I-expressing strains were common in all regions (17%), as were ETEC expressing CFA/II (9%) and IV (18%). Marked variation in toxins and CFs across regions and populations was observed.
  
  
  CONCLUSIONS
  These results demonstrate the relative importance of specific CFs in achieving target product profiles for a future ETEC vaccine. However, heterogeneity across time, population, and region, confounded by variability in CF and toxin detection methodologies, obfuscates rational estimates for valency requirements.
authors: Enteric Diseases Department, Infectious Disease Directorate, Naval Medical Research Center, 503 Robert Grant Avenue, Silver Spring, MD 20910-7500, USA.
authors: S D
authors: SD
authors: Isidean
authors: M S
authors: MS
authors: Riddle
authors: S J
authors: SJ
authors: Savarino
authors: C K
authors: CK
authors: Porter
mesh_terms: D001427:Bacterial Toxins / Q000096:biosynthesis*; D054307:Enterotoxigenic Escherichia coli / Q000145:classification / Q000276:immunology / Q000302:isolation & purification; D004768:Enterotoxins / Q000096:biosynthesis*; D004927:Escherichia coli Infections / Q000453:epidemiology*; D029968:Escherichia coli Proteins / Q000096:biosynthesis*; D022361:Escherichia coli Vaccines; D036781:Fimbriae Proteins / Q000096:biosynthesis*; D006801:Humans
chemical_list: D001427:Bacterial Toxins; D004768:Enterotoxins; D029968:Escherichia coli Proteins; D022361:Escherichia coli Vaccines; C022924:colonization factor antigens; C034151:heat stable toxin (E coli); D036781:Fimbriae Proteins; C027538:heat-labile enterotoxin, E coli