The two groups reported similar rates of handwashing on a short questionnaire. For five weeks, investigators tracked the families, phoning almost every other week to record how much hand sanitizer have been used, whether someone had developed a GI or respiratory infection, and if the illness had spread to others in the real home. The families given hands sanitizer had a 59 % lower incidence of secondary GI illnesses as compared with the control group, after adjustment for other factors such as the number of young children in the household. In addition, families reporting higher quantities sanitizer usage had been about 20 % less inclined to transmit respiratory illnesses, but this effect didn’t reach statistical significance.Customers in the first ’90s,’ Yoon said. ‘But the first registered problem was reported from Israel in 1995, because they had it used even earlier probably. After that in 2000 we discovered genetic mutations causing resistance in head lice here.’ Mind lice, which can’t jump or fly, transmit simply by direct physical contact. They infest the throat and head quickly, feeding on blood and attaching their eggs to the base of hair shafts. ‘They itch, but they do not transmit disease,’ said Yoon. ‘So it’s not at all life-threatening, even if it’s very irritating and uncomfortable.’ Six million to 12 million U.S.