Enhancing handwashing frequency and technique of primary caregivers in Harare, Zimbabwe: A cluster -randomized controlled trial using behavioral and microbial outcomes

Rationale: Consistent hand hygiene prevents diarrheal and respiratory diseases, but it is often not practiced. The disease burden is highest in low-income settings, which need effective interventions to promote domestic handwashing. To date, most handwashing campaigns have focused on promoting frequent handwashing at key times, whereas specifically promoting handwashing techniques proven to be effective in removing microbes has been confined to healthcare settings. Methods: We used a cluster-randomized, factorial, controlled trial to test the effects of two handwashing interventions on the behavior of primary caregivers in Harare, Zimbabwe. One intervention targeted caregivers directly, and the other targeted them through their children. Outcome measures were surveyed at baseline and six weeks' follow-up and included observed handwashing frequency and technique and fecal hand contamination before and after handwashing. Results: Combining the direct and indirect interventions resulted in observed handwashing with soap at 28% of critical handwashing times, while the corresponding figure for the non-intervention control was 5%. Observed handwashing technique, measured as the number of correctly performed handwashing steps, increased to an average of 4.2, while the control averaged 3.4 steps. Demonstrated handwashing technique increased to a mean of 6.8 steps; the control averaged 5.2 steps. No statistically significant group differences in fecal hand contamination before or after handwashing were detected. Conclusions: The results provide strong evidence that the campaign successfully improved handwashing frequency and technique. It shows that the population-tailored design, based on social-cognitive theory, provides effective means for developing powerful interventions for handwashing behavior change. We did not find evidence that children acted as strong agents of handwashing behavior change. The fact that the microbial effectiveness of handwashing did not improve despite strong improvements in handwashing technique calls for critical evaluation of existing handwashing recommendations. The aim of future handwashing campaigns should be to promote both frequent and effective handwashing.