Household Flooring Associated with Reduced Infant Diarrheal Illness in Zimbabwe in Households with and without WASH interventions.

Objectives Diarrhoeal illness is a leading cause of childhood morbidity and mortality and has long-term negative impacts on child development. Although flooring, water and sanitation have been identified as important routes of transmission of diarrhoeal pathogens, research examining variability in the association between flooring and diarrhoeal illness by water and sanitation is limited. Methods We utilised cross-sectional data collected for the evaluation of Zimbabwe's Prevention of Mother-to-Child HIV transmission programme in 2014 and 2017-18. Mothers of infants 9-18 months of age self-reported the household's source of drinking water and type of sanitation facility, as well as infant diarrhoeal illness in the four weeks prior to the survey. Household flooring was assessed using interviewer observation, and households in which the main material of flooring was dirt/earthen were classified as having unimproved flooring, and those with solid flooring (e.g. cement) were classified as having improved flooring. Results Mothers of infants living in households with improved flooring were less likely to report diarrhoeal illness in the last four weeks (PDa = -4.8%, 95% CI: -8.6, -1.0). The association between flooring and diarrhoeal illness did not vary by the presence of improved/unimproved water (p(RERI) = 0.91) or sanitation (p(RERI) = 0.76). Conclusions Our findings support the hypothesis that household flooring is an important pathway for the transmission of diarrhoeal pathogens, even in settings where other aspects of sanitation are sub-optimal. Improvements to household flooring do not require behaviour change and may be an effective and expeditious strategy for reducing childhood diarrhoeal illness irrespective of household access to improved water and sanitation.