COMPARATIVE IN-VIVO EFFICIENCIES OF HAND-WASHING AGENTS AGAINST HEPATITIS-A VIRUS (HM-175) AND POLIOVIRUS TYPE-1 (SABIN)

The abilities of 10 hygienic hand-washing agents and tap water (contai ning approximately 0.5 ppm of free chlorine) to eliminate strain HM-17 5 of hepatitis A virus (HAV) and poliovirus (PV) type 1 (Sabin) were c ompared by using finger pad and whole-hand protocols with three adult volunteers. A mixture of the two viruses was prepared in a 10% suspens ion of feces, and 10 mul of the mixture was placed on each finger pad. The inoculum was allowed to dry for 20 min, and the contaminated area was exposed to a hand-washing agent for 10 s, rinsed in tap water, an d dried with a paper towel. In the whole-hand protocol, the hands were contaminated with 0.5 ml of the virus mixture, exposed for 10 s to a band-washing agent, washed, and dried as described above. Tryptose pho sphate broth was used to elute any virus remaining on the finger pads or hands. One part of the eluate was assayed directly for PV with FRhK -4 cells, while the other part was first treated with a PV-neutralizin g serum and then assayed for HAV with the same cell line. The results are reported as mean percentages of reduction in PFU compared with the amount of infectious virus detectable after initial drying. In the fi nger pad protocol, an unmedicated liquid soap was the least effective agent (77.96% +/- 7.17% reduction) for removing HAV, and a medicated l iquid soap was the most effective agent (92.04% +/- 4.02% reduction) f or reducing the HAV titer; the smallest reduction in PV titer was obta ined with tap water (85.22% +/- 2.91% reduction), and the same medicat ed soap was the most effective agent against PV (98.39% +/- 1.98% redu ction). Significant differences were found between HAV removal and PV removal with 9 of the 11 agents tested (F = 102.14; P < 0.05). There w as good correspondence between the results of the finger pad protocol and the results of the whole-hand method. In additional experiments, w e attempted to transfer infectious virus remaining on finger pads trea ted with various hand-washing agents by having the finger pads contact clean metal disks at a pressure of about 1 kg/cm2 for 10 s. Detectabl e amounts of both of the viruses were transferred after washing with a ll of the agents except a 1:30 dilution of a mixture containing 1.5% c hlorhexidine gluconate and 15% cetrimide in 70% ethanol, 70% ethanol a lone, and a foam containing 62% ethanol. More work is needed to determ ine the health implications of residual infectious viruses on washed h ands, but our findings reinforce the need to determine the virus-elimi nating efficiencies of hand-washing products, particularly those used in health care settings, day-care centers, and food establishments.