Hand gels falter.

Alcohol-based gels may not effectively eliminate from people's hands a type of virus that causes millions of cases of diarrhea worldwide each year, say researchers.

Such hand sanitizers are rising in popularity because of their convenience, says Christine Moe of Emory University in Atlanta. Unlike washing with soap and water, using these gels doesn't require rinsing or drying one's hands.

Because the gels have been shown to kill a wide variety of bacteria and viruses, Moe adds, they're becoming a common fixture in places where frequent hand washing is necessary. Until now, however, researchers hadn't tested the effectiveness of such sanitizers against noroviruses, a family of viruses that causes gastrointestinal infections and has become notorious for spreading among passengers on cruise ships.

Moe and her colleagues recruited five volunteers to come into the lab. The scientists spread a known amount of Norwalk virus, a common type of norovirus, on the volunteers' fingers. To each of three fingers, the researchers then applied one of three cleansing agents--antibacterial soap rinsed with water, plain water, or a popular alcohol-based hand sanitizer. Each volunteer's fourth finger remained unwashed for comparison.

To the researchers' surprise, plain water was most effective, removing 96 percent of Norwalk virus. Antibacterial soap was close behind, reducing viral counts by 88 percent. The alcohol-based hand gels reduced the virus by only about half.

Alcohol-based hand gels "are better than nothing, but in areas where soap mad water are available, people should use those first," Moe says.--C.B.