A study from Pakistan shows that the simple act of handwashing with soap can sharply reduce the chances a child will get pneumonia and diarrhea, the two leading causes of childhood deaths in poor countries. But the practice will take much effort to promote.

Diarrhea and respiratory tract infections kill 3.5 million children under age five each year.  A study in the medical journal Lancet by U.S. and Pakistani public health experts shows that this number could be cut in half if handwashing with soap were common practice.

Researcher Stephen Luby of the U.S. Centers for Disease Control and colleagues offered free soap and weekly encouragement to 600 families living in a squatter settlement in Karachi. He says that after one year, the incidence of pneumonia and diarrhea was 50 percent lower among young children in those families than in another group of 300 families who did not receive soap or weekly advice from fieldworkers.

"Respiratory organisms are transmitted on the hand and by removing those, we will interrupt transmission," said Mr. Luby.   "This has been looked at in some developed country settings. This is the first time it has really been looked at in low income settings where pneumonia is a leading cause of death. But we would expect this same mechanism to be effective in other places."

In addition to the benefit against pneumonia and diarrhea, the Karachi study also shows that handwashing with soap lowered the incidence of the contagious skin infection impetigo by one-third.

"I think it's really easy for us to look at the problems of global poverty and global childhood mortality and to become hopeless," he added.  "I think one of the things this study suggests is that there are low cost things that can be done to improve the lives and health of people living in these poor settings."

At the University of Geneva Hospital, hygiene expert Didier Pittet calls the study remarkable.  While it measured only disease rates and not mortality, he says carrying out handwashing on a large scale would undoubtedly save millions of children's lives.

"Clearly soap and education made an extraordinary benefit to children in this part of the world. Could we reproduce this on a larger scale? It would be difficult, but why don't we try? It's a very simple action and it works," said Dr. Pittet.

Dr. Pittet notes that although soap in Karachi costs only one dollar per household per week, it is still expensive when family income averages only $15 a week.  He suggests that soap and advice be provided free in developing nations, perhaps by a public-private partnership like the Central American Handwashing Initiative of the late 1990s. In that program, governments, donor agencies, and four soap companies cooperated to promote clean hands to fight diarrhea in the region, despite poor sanitation.

"Let's think about the fact that if companies would like to provide soap freely around the world or if we can just get some solidarity," added Mr. Pittet.  "Let's say that every time we buy five soaps, we would give one or half a soap to Africa or to Asia or to South America, to these poor countries, I think we can do it. I mean, this is easy."

Dr. Pittet is leading a new World Health Organization (WHO) program to promote hand cleaning and other hygienic practices among health care workers in developing countries. As he puts it, the time has come to shout from the roof tops that hand hygiene promotion should be a worldwide public health priority.