title: Variability in hand contamination based on serial measurements: implications for assessment of hand-cleansing behavior and disease risk.
abstract: Measuring hand contamination at critical times, such as eating, can be challenging. We examined whether hand contamination measured at random, such as on arrival (initial), predicts contamination at critical times. Mothers of young children in Bangladesh rinsed both hands in 200 mL of Ringer's solution. We compared results of serial samples with respect to fecal coliform counts. Among 39 mothers, the geometric mean of fecal coliforms was 307 colony-forming units (cfu)/100 mL at initial collection and 3,001 cfu/100 mL during critical times (P = 0.0006). There was no correlation between initial and critical time fecal coliform counts (R = 0.13, P = 0.43). The mean difference between initial and critical time counts was 3.5 (standard deviation = 1.4) on the log base-10 scale. Contamination of the same subjects' hands varied substantially within a few hours. Because hand contamination measured at random cannot reliably predict hand contamination at times of potential pathogen transmission, single random hand rinses are not valid proxy measures for handwashing behavior.
authors: University at Buffalo, 3435 Main Street, Buffalo, NY 14221, USA. pkram@buffalo.edu
authors: Pavani K
authors: PK
authors: Ram
authors: Iqbal
authors: I
authors: Jahid
authors: Amal K
authors: AK
authors: Halder
authors: Benjamin
authors: B
authors: Nygren
authors: M Sirajul
authors: MS
authors: Islam
authors: Stewart P
authors: SP
authors: Granger
authors: John W
authors: JW
authors: Molyneaux
authors: Stephen P
authors: SP
authors: Luby
mesh_terms: D000328:Adult; D001459:Bangladesh / Q000453:epidemiology; D002675:Child, Preschool; D004755:Enterobacteriaceae / Q000302:isolation & purification*; D005260:Female; D006225:Hand / Q000382:microbiology*; D006235:Hand Disinfection / Q000592:standards*; D006801:Humans; D012307:Risk Factors