bioRxiv2025
Soil-transmitted helminths, like Ascaris, are significant contributors to disease burden in low- and middle-income countries (LMICs). Infections are associated with growth faltering and mortality in children and are often transmitted through contact with eggs in fecally contaminated soil. Interventions, like replacing household soil floors with cement-based alternatives, may reduce exposure to Ascaris eggs, but there are currently no estimates on the removal or survival of Ascaris eggs on cement-based surfaces. This study addresses that knowledge gap by evaluating the removal of Ascaris eggs from mopping and the survival of Ascaris eggs on two cement-based mixes: an Ordinary Portland Cement (OPC) mortar and an OPC mortar with fly ash, which provides a more sustainable alternative to the OPC mortar mix. We assessed egg survival at two temperatures representing the dry (15{degrees}C) and wet (34{degrees}C) seasons in Bangladesh using two different egg enumeration methods. After mopping, over 92% of viable eggs were removed from surfaces, with no significant differences between cement-based mixes (p = 0.51). The first-order decay rate constants (k) of Ascaris eggs were similar between mix designs (p = 0.62) but varied significantly between temperatures (p = 4.2 x 10-25) and egg enumeration methods (p = 2.4 x 10-8). The k values were of greater magnitude at 34{degrees}C compared to at 15{degrees}C. At 15{degrees}C, k values were not significantly different from zero, indicating no inactivation. The k values we obtained were comparable to those reported in previous studies for different matrices, indicating comparable inactivation of Ascaris eggs on cement-based surfaces compared to liquid and semi-solid matrices. These results provide some of the first estimates of removal efficiencies and inactivation times in realistic environmental conditions for Ascaris on surfaces while supporting the use of OPC mortar mix designs with fly ash in interventions to reduce Ascaris transmission in rural LMIC households. Author SummarySoil-transmitted helminths, like Ascaris, are parasites that are major contributors to disease in children and women of childbearing age in low- and middle-income countries. Interventions, like replacing soil floors in households with cement-based flooring, may reduce exposure to Ascaris eggs which cause infections, but there is little information on how or why these interventions may be effective. This study investigates the effectiveness of simple cleaning methods, like mopping, in removing Ascaris eggs from cement-based surfaces and explores how long these eggs can survive on these surfaces under different environmental conditions. We tested two types of cement-based surfaces, a traditional cement-based mortar mix, and a more sustainable cement-based mortar mix, and found that mopping removed over 92% of Ascaris eggs, with no differences between cement mixes. Experiments simulating wet and dry seasonal conditions showed that Ascaris eggs survive longer in cooler environments, again with no differences between cement mixes. These findings provide important insights into the role of cement-based flooring in interrupting disease transmission and suggest sustainable cement-based mortar mixes are a feasible alternative to traditional cement-based mortar mixes.