Handwashing with soap improves health and saves lives by preventing infections. Many infections start when hands are contaminated with disease-causing bacteria and viruses. This can happen after using the toilet, changing a child’s diaper, coughing, sneezing, touching other people’s hands, and touching other contaminated surfaces. A single gram of human feces can contain 10 million viruses and one million bacteria, and infant feces are particularly pathogenic.[i] Handwashing with soap works by removing bacteria and viruses from hands before they get a chance to cause infections or spread to other people. This is why cleaning hands with soap, particularly after contact with fecal material from using the toilet or cleaning a child’s bottom, is so important.

When hands are contaminated with disease-causing bacteria and viruses, these pathogens can enter the body or pass from person-to-person. Once these bacteria and viruses enter the body, they can cause a wide range of infections.

Two major illnesses that are transmitted on the hands are diarrhea and pneumonia. Together, diarrhea and pneumonia kill an estimated 1.7 million children every year. Many of these deaths can be prevented by handwashing with soap.[ii] Other infections that handwashing with soap can help prevent include Ebola, skin and eye infections; intestinal worms, and healthcare-associated infections.

Read about handwashing and its impact on different infections below.

Have additional questions about handwashing with soap? Visit our Frequently Asked Questions page, or click here to ask an expert.


Each day 2,195 children die from diarrhea. This makes it one of the top killers of children under the age of five globally.[iii] Almost all causes of childhood diarrhea are caused by infections, which means that most of these deaths are entirely preventable. One of the most effective ways of preventing diarrhea is by handwashing with soap. In fact, a review of more than 40 studies found that handwashing with soap can prevent four out of every 10 cases of diarrhea.[iv] Children living in households where there is active handwashing promotion and available soap have half the rates of diarrhea compared to children without these.[v]

Diarrheal diseases are often described as water-related but should more accurately be known as excreta-related, as the bacteria and viruses (germs) that cause diarrhea come from fecal matter (poo). These germs make people ill when they enter the mouth via hands that have been in contact with feces, contaminated drinking water, unwashed raw food, unwashed utensils, or smears on clothes. Handwashing with soap breaks this cycle.

Pneumonia and Acute Respiratory Infections

Acute respiratory infections like pneumonia are another leading cause of death in children under the age of five. Handwashing reduces the rate of respiratory infections in two ways: by removing respiratory pathogens found on hands and surfaces and by removing other pathogens, such as viruses that affect the gut, found to cause both diarrhea and respiratory symptoms. Evidence suggests that washing hands with soap after defecation and before eating could cut the respiratory infection rate by about 21-25 percent.[vi][vii] However, the full effect might turn out to be even bigger. For example, a study in Pakistan found that handwashing with soap reduced the number of pneumonia related infections in children under the age of five by more than 50 percent.[viii] [ix]

Proper handwashing helps prevent the spread of cold and flu by removing viruses that get onto hands from coughs and sneezes. This is particularly important during flu season. Materials such as posters that can be used to promote good hand hygiene during peak seasons of respiratory illness or flu transmission can be found at this link.


Ebola virus disease is a severe and often fatal acute viral disease that can spread from animal to human or from human to human, both through direct contact with an infected person or animal’s bodily fluids and through contact with surfaces that have been contaminated with these infected bodily fluids. Handwashing with soap is an important component of Ebola infection protection.

Given the impact of Ebola and the role of handwashing, the PPPHW has developed an Ebola Key Topics page. Additional information about Ebola is available on this World Health Organization factsheet and FAQs, as well as the WHO/UNICEF Ebola and water, sanitation, and hygiene questions and answers page.

Skin & Eye Infections

Though not as extensive and robust as the research evidence for diarrheal disease and respiratory infections, studies have shown that handwashing with soap reduces the incidence of skin diseases and eye infections like trachoma.[x][xi]

Intestinal Worms

While more evidence is needed, existing research shows that handwashing with soap reduces the incidence of intestinal worms, especially ascariasis and trichuriasis.[xii]

Healthcare-Associated Infections

Healthcare-associated infections (HAIs) affect 15 out of every 100 patients during a hospital stay; the rate is even higher in intensive care units, in low-resource settings, and for newborns.[xiii] HAIs impact hundreds of millions of patients every year. They can cause short-term illness, long-term disability, and death. They also contribute to longer hospital stays, antibiotic resistance, and a massive financial impact for patients, families, and entire health care systems. Most HAIs can be prevented through good hand hygiene—cleaning hands at the right times and in the right way, either by handwashing with soap or utilizing alcohol-based hand rubs. Good hand hygiene in healthcare has saved millions of lives, but currently only about 40 percent of health workers globally practice good hand hygiene.[xiv]

The World Health Organization’s Clean Care is Safer Care campaign works to improve hand hygiene amongst healthcare workers.



[i] Majorin F, Freeman MC, Barnard S, Routray P, Boisson S, Clasen T. Child Feces Disposal Practices in Rural Orissa: A Cross Sectional Study. PLoS One. 2014 Feb 20;9(2):e89551

[ii]UNICEF. Committing to Child Survival: A Promise Renewed Progress Report 2013. Published September 2013. Accessed January 22, 2015.

[iii] CDC. Diarrhea: Common Illness, Global Killer. Published January 24, 2013. Accessed January 22, 2015.

[iv] Freeman MC, Stocks M, Cumming O, Jeandron A, Higgins JPT, Wolf J, Prüss-Ustün A, Bonjour S, Hunter PR, Fewtrell L, Curtis V. Hygiene and health: systematic review of handwashing practices worldwide and update of health effects. Tropical Medicine and International Health 19(8): 906-16.

[v] Luby, S. P. et al. (2005). Effect of handwashing on child health: A randomised controlled trial. The Lancet, 366(9481), 225-233.

[vi] Aiello, AE, Coulborn RM, Perez V, Larson EL. Effect of Hand Hygiene on Infectious Disease Risk in the Community Setting: A Meta-Analysis. Am J Public Health. 2008 August; 98(8): 1372–1381.

[vii] Curtis, V. & Cairncross, S. (2003). Effect of washing hands with soap on diarrhoea risk in the community: A systematic review. The Lancet Infectious Diseases, 3(5), 275-281.

[viii] Luby, S. P. et al. (2005). Effect of handwashing on child health: A randomised controlled trial. The Lancet, 366(9481), 225-233.

[ix] Talaat M1, Afifi S, Dueger E, El-Ashry N, Marfin A, Kandeel A, Mohareb E, El-Sayed N. Effects of hand hygiene campaigns on incidence of laboratory-confirmed influenza and absenteeism in schoolchildren, Cairo, Egypt. Emerg Infect Dis. 2011 (4):619-25.

[x] Ngondi, J., et al., Associations between Active Trachoma and Community Intervention with Antibiotics, Facial Cleanliness, and Environmental Improvement (A,F,E). PLoS Negl Trop Dis, 2008. 2(4): p. e229.

[xi] Stocks ME, Ogden S, Haddad D, Addiss DG, McGuire C, Freeman MC. Effect of water, sanitation, and hygiene on the prevention of trachoma: a systematic review and meta-analysis. PLoS Med. 2014 Feb 25;11(2):e1001605. doi: 10.1371/journal.pmed.1001605. eCollection 2014.

[xii] Freeman MC, Clasen T, Brooker SJ, Akoko DO & Rheingans R (2013) The impact of a school-based hygiene, water quality and sanitation intervention on soil-transmitted helminth reinfection: a cluster-randomized trial. The American Journal of Tropical Medicine and Hygiene 89, 875–883.

[xiii] WHO/UNICEF (2015). Water, sanitation and hygiene in health care facilities: Status in low- and middle-income countries and way forward.

[xiv] Benedetta Allegranzi, Sepideh Bagheri Nejad, Christophe Combescure, Wilco Graafmans, Homa Attar, Liam Donaldson, Didier Pittet, Burden of endemic health-care-associated infection in developing countries: systematic review and meta-analysis, The Lancet, Volume 377, Issue 9761, 15–21 January 2011, Pages 228-241.