Handwashing and Ebola virus disease outbreaks: A randomized comparison of soap, hand sanitizer, and 0.05% chlorine solutions on the inactivation and removal of model organisms Phi6 and E. coli from hands and persistence in rinse water

PLoS One. 2017 Feb 23;12(2):e0172734. doi: 10.1371/journal.pone.0172734. eCollection 2017.

Abstract

To prevent Ebola transmission, frequent handwashing is recommended in Ebola Treatment Units and communities. However, little is known about which handwashing protocol is most efficacious. We evaluated six handwashing protocols (soap and water, alcohol-based hand sanitizer (ABHS), and 0.05% sodium dichloroisocyanurate, high-test hypochlorite, and stabilized and non-stabilized sodium hypochlorite solutions) for 1) efficacy of handwashing on the removal and inactivation of non-pathogenic model organisms and, 2) persistence of organisms in rinse water. Model organisms E. coli and bacteriophage Phi6 were used to evaluate handwashing with and without organic load added to simulate bodily fluids. Hands were inoculated with test organisms, washed, and rinsed using a glove juice method to retrieve remaining organisms. Impact was estimated by comparing the log reduction in organisms after handwashing to the log reduction without handwashing. Rinse water was collected to test for persistence of organisms. Handwashing resulted in a 1.94-3.01 log reduction in E. coli concentration without, and 2.18-3.34 with, soil load; and a 2.44-3.06 log reduction in Phi6 without, and 2.71-3.69 with, soil load. HTH performed most consistently well, with significantly greater log reductions than other handwashing protocols in three models. However, the magnitude of handwashing efficacy differences was small, suggesting protocols are similarly efficacious. Rinse water demonstrated a 0.28-4.77 log reduction in remaining E. coli without, and 0.21-4.49 with, soil load and a 1.26-2.02 log reduction in Phi6 without, and 1.30-2.20 with, soil load. Chlorine resulted in significantly less persistence of E. coli in both conditions and Phi6 without soil load in rinse water (p<0.001). Thus, chlorine-based methods may offer a benefit of reducing persistence in rinse water. We recommend responders use the most practical handwashing method to ensure hand hygiene in Ebola contexts, considering the potential benefit of chlorine-based methods in rinse water persistence.

Publication types

  • Comparative Study
  • Randomized Controlled Trial

MeSH terms

  • Adolescent
  • Bacteriophage phi 6 / drug effects*
  • Bacteriophage phi 6 / isolation & purification
  • Chlorine*
  • Disease Outbreaks / prevention & control*
  • Escherichia coli / drug effects*
  • Escherichia coli / isolation & purification
  • Female
  • Hand Disinfection / methods*
  • Hand Sanitizers*
  • Hemorrhagic Fever, Ebola
  • Humans
  • Male
  • Soaps*
  • Water Microbiology
  • Young Adult

Substances

  • Hand Sanitizers
  • Soaps
  • Chlorine

Grants and funding

This study was funded by a grant from the United States Agency for International Development, Office of Foreign Disaster Assistance (AID-OFDA-A-15-00026). MW was supported by the National Science Foundation (grant 0966093). The funders had no role in data collection and analysis, decision to publish, or preparation of the manuscript. The funders had no input into study design after the grant was awarded. The funders were provided a final version of the manuscript before submission, and had only minor grammatical comments.