Here is why: Human feces are the main source of diarrheal pathogens. They are the source of shigellosis, typhoid, cholera, all other common endemic gastro-enteric infections and some respiratory infections such as influenza and pneumonia. A single gram of human feces can contain 10 million viruses and one million bacteria.
These pathogens are passed from an infected host to a new one via various routes but all of these illnesses emanate from feces. Removing excreta and cleaning hands with soap after contact with fecal material –from using the toilet or cleaning a child – prevents the transmission of the bacteria, viruses and protozoa that cause diarrheal diseases.
Other measures (food handling, water purification, and fly control) have an impact on these diseases as well, but sanitation and handwashing provide the necessary protection against fecal contact. They start by creating initial barriers to fecal pathogens from reaching the domestic environment. Handwashing with soap stops the transmission of disease agents and so can significantly reduce diarrhea and respiratory infections, and may impact skin and eye infections.
Research shows that children living in households exposed to handwashing promotion and soap had half the diarrheal rates of children living in control neighborhoods. Because handwashing can prevent the transmission of a variety of pathogens, it may be more effective than any single vaccine. Promoted on a wide enough scale, handwashing with soap can be thought of as a “do-it-yourself” vaccine. Ingraining the habit of handwashing could save more lives than any single vaccine or medical intervention.