Establishing evidence for common-but-underresearched WASH cholera interventions

WHAT DID THIS STUDY SET OUT TO ACHIEVE?

The purpose of this research was to establish the laboratory efficacy and field effectiveness of under-researched, on-going public health interventions commonly implemented to prevent cholera transmission in humanitarian crises, including:

1. household spraying
2. distribution of household disinfection kits
3. bucket chlorination.

These interventions are widely implemented in cholera response activities but lack both the fundamental laboratory data on efficacy (e.g. when you spray chlorine on a surface with Vibrio cholerae on it, is the bacteria inactivated?) and field effectiveness (e.g. how effective are programs as implemented in emergency response). This research aimed to fill these evidence gaps using laboratory research methods and mixed-methods field research, including household surveys, key informant interviews, focus group discussions, water quality testing, and household surface testing.

WHAT WERE THE KEY FINDINGS?

• Lab research showed that household spraying is most efficacious using 0.2% chlorine sprayed on all surfaces, or wiped on most non-heavily soiled surfaces, and 2.0% concentration on contaminated porous surfaces. Surfaces must be visibly wetted to achieve disinfection.
• Bucket chlorination can be efficacious at inactivating V. cholerae bacteria and providing residual chlorine when dosage is determined by a jar test using all three commonly used chlorine types (HTH, NaDCC, NaOCI).
• However, effectiveness for both interventions varied in the field, depending on how they were implemented in each context.
• Responders in the field were not familiar with household disinfection kits, preferring household spraying. Therefore, a field evaluation of kits was not conducted.

WHAT DOES THIS MEAN FOR POLICYMAKERS AND PRACTITIONERS?

• To ensure bucket chlorination effectiveness matches efficacy, it is recommended to conduct more frequent dosing (jar) tests, regularly monitor chlorine residual at the household level, and safely store chlorine solutions away from heat and sun.
• It is recommended to conduct regular monitoring in bucket chlorination programmes, including:
  • Assurance testing of chlorine solution concentration
  • Chlorine residual at the household level.
• To make household spraying most effective, spraying agents should: disinfect surfaces systematically until wet using 0.2/2.0% chlorine solution, including kitchen spaces, patients’ beds, and latrines; arrive at households quickly; and concurrently deploy hygiene promotion activities.
• The fact no hygiene distribution kit intervention could be found for evaluation emphasises the gap between the current international-level policy and the realities of cholera response programmes.
• There is a need for greater attention to the dissemination of new evidence and training of responders and affected populations regarding methods to prevent cholera transmission.