Microbiologic effectiveness of hand washing with soap in an urban squattersettlement, Karachi, Pakistan

We conducted a study in a squatter settlement in Karachi, Pakistan where re sidents report commonly washing their hands to determine if providing soap, encouraging hand washing, and improving wash-water quality would improve h and cleanliness. We allocated interventions to 75 mothers and collected han d-rinse samples on unannounced visits. In the final model compared with mot hers who received no hand-washing intervention, mothers who received soap w ould be expected to have 65% fewer thermotolerant coliform bacteria on thei r hands (95% CI 40%, 79%) and mothers who received soap, a safe water stora ge vessel, hypochlorite for water treatment, and instructions to wash their hands with soap and chlorinated water would be expected to have 74% fewer (95% C1 57%, 84%). The difference between those who received soap alone, an d those who received soap plus the safe water vessel was not significant (P = 0.26). Providing soap and promoting hand washing measurably improved mot hers' hand cleanliness even when used with contaminated water.