The simple act of washing hands with soap can significantly cut the risk of diarrhea (from 30 percent to 50 percent, Fewtrell et al., 2005) and that of respiratory tract infection (from 21 percent to 45 percent, Curtis and Cairncross, 2003)
UNICEF estimates that diarrhea kills one child every 30 seconds. Scientific research shows that handwashing with soap prevents disease in a more straightforward and cost-effective way than any single vaccine.
The World Health Organization (WHO) estimates that diarrheal infections claim the lives of 1.87 million children under five each year, making diarrhea the second-most common cause of death among children under five.
Diarrheal diseases are often described as water-related, but they are more accurately excreta-related since the pathogens come from fecal matter. These pathogens make people ill when they enter the mouth via hands that have been in contact with feces. Handwashing with soap breaks the disease cycle. In 2005, Fewtrell et al. 2005 compared the effectiveness of handwashing with soap for reducing diarrheal illness to other interventions.
Acute respiratory infections such as pneumonia are another primary cause of child deaths. Handwashing reduces the rate of respiratory infections in two ways: by removing respiratory pathogens found on hands and surfaces; and by removing other pathogens (in particular, enteric viruses) found to cause diarrhea and respiratory symptoms. Evidence suggests that better hygiene practices – washing hands with soap after defecation and before eating – could cut the infection rate by about 25 percent.
A study in Pakistan found that handwashing with soap reduced the number of pneumonia-related infections in children under five by more than 50 percent, as well as skin infection – impetigo – by 34 percent.
Research shows that handwashing with soap reduces the incidence of infections like intestinal worms, especially ascariasis and trichuriasis. While more evidence is needed, existing research points to the effectiveness of handwashing in reducing the incidence of these diseases.