Handwashing with soap prevents many common and life-threatening infections. Many illnesses start when hands become contaminated with disease-causing bacteria and viruses. This can happen after using the toilet, contact with a child’s excreta, coughing, sneezing, touching other people’s hands, and touching other contaminated surfaces. For example, a single gram of human feces can contain 10 million viruses and one million bacteria, and infant feces are particularly pathogenic.[i]
When hands are contaminated with disease-causing bacteria and viruses, these pathogens can enter the body or pass from one person to another to cause disease. Two major illnesses that are transmitted on the hands are diarrhea and pneumonia. Together, diarrhea and pneumonia cause more than 20% of deaths of children under the age of five.[ii] Many of these deaths can be prevented by handwashing with soap.
Handwashing with soap works by removing bacteria and viruses before they can enter the body or spread to other people. Cleaning hands with soap, particularly before eating or preparing food, and after contact with fecal material from using the toilet or cleaning a child’s bottom, is one of the most effective ways to prevent disease. Learn more about handwashing and health below.
Each year, around 525,000 children die from diarrheal diseases, making it one of the top killers of children 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 diarrheal diseases is handwashing with soap.
Diarrheal diseases are often described as water-related, but should more accurately be known as excreta-related, as the germs and parasites which cause diarrhea come from fecal matter. These microbes make people ill when they enter the mouth via hands that have been in contact with feces, contaminated drinking water, unwashed raw foods, unwashed utensils, or other contaminated sources. Handwashing with soap helps to break fecal-oral transmission routes.
A review of more than 40 studies found that handwashing with soap can prevent approximately 4 of every 10 cases of diarrhea.[iv] Children living in households where soap is available and in neighborhoods where handwashing is actively promoted were found to have half the rates of diarrhea compared to children living in households without these factors.[v]
Pneumonia and Acute Respiratory Infections
Acute respiratory infections, including pneumonia, are another leading cause of death in children under the age of five.[vi] Pneumonia alone accounts for approximately 13% of child deaths. Handwashing reduces the rate of respiratory infections by removing respiratory pathogens from hands, and preventing them from entering the body or passing on to other people. Evidence suggests that washing hands with soap after defecation and before eating can cut the respiratory infection rate by up to 25%.[vii][viii] One 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%.[ix]
Proper handwashing also 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 to promote good hand hygiene during peak seasons of respiratory illness or flu transmission can be found at this link.
Healthcare-associated infections (HCAI), also known as nosocomial infections, affect 15.5% of patients in developing countries and contribute to antimicrobial resistance, which causes 700,000 deaths each year.[x] HCAIs impact hundreds of millions of patients every year, and often lead to other infections, long-term disability, and death. HCAIs prolong recovery time and hospital stays, result in disability, increase medical costs, and pose life-threatening risks for patients.[xi]
Most HCAIs can be prevented through good hand hygiene. For effective hand hygiene, all staff in healthcare facilities (HCF) must wash or disinfect their hands at 5 critical moments: before patient contact, before an aseptic task, after body fluid exposure risk, after patient contact, and after contact with patient surroundings.[xii] Good hand hygiene in healthcare saves millions of lives, but currently only about 40% of healthcare workers globally practice good hand hygiene.[xiii]
Visit our key topics page on Hygiene in Healthcare Facilities to learn more.
Handwashing with soap can play a key role in preventing or slowing outbreaks. For example, proper handwashing with soap can remove the germs that cause Ebola Virus Disease or other hemorrhagic infections. It is also a critical practice to prevent cholera infections.
Ebola virus disease is a severe and often fatal acute viral hemorrhagic infection that can spread from animal to human and 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 infected bodily fluids. Handwashing with soap is an important component of Ebola prevention.
It is estimated that cholera kills up to 143,000 people per year.[xiv] Cholera is caused by ingesting contaminated water or food, and handwashing with soap is a vital part of cholera prevention. Read our fact sheet to learn more.
Other infections and intestinal worms
Studies have shown that handwashing with soap reduces the incidence of skin diseases and eye infections like trachoma.[xv][xvi] Research also shows that handwashing with soap reduces the incidence of intestinal worms, particularly ascariasis and trichuriasis.[xvii] Handwashing with soap is the most effective way to prevent pinworm infections.[xviii]
[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; 9(2): e89551.
[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. Trop Med Int Health, 2014; 19(8): 906-16.
[v] Luby SP, et al. Effect of handwashing on child health: A randomised controlled trial. Lancet, 2015; 366(9481): 225-33.
[vi] UNICEF (n.d.). Data: Monitoring the Situation of Children and Women.
[vii] 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 Pub Health, 2008; 98(8): 1372-81.
[viii] Curtis V, Cairncross S. Effect of washing hands with soap on diarrhoea risk in the community: A systematic review. Lancet Infect Dis, 2003; 3(5), 275-81.
[ix] Luby SP, et al. Effect of handwashing on child health: A randomised controlled trial. Lancet, 2015; 366(9481): 225-33.
[x] Allegranzi B, et al. Burden of endemic health-care-associated infection in developing countries: systematic review and meta-analysis. Lancet, 2011; 377(9761): 228-41.
[xiii] Allegranzi B, et al. Burden of endemic health-care-associated infection in developing countries: systematic review and meta-analysis. Lancet, 2011.
[xv] 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): e229.
[xvi] 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; 11(2).
[xvii] Freeman MC, Clasen T, Brooker SJ, Akoko DO & Rheingans R. The impact of a school-based hygiene, water quality and sanitation intervention on soil-transmitted helminth reinfection: a cluster-randomized trial. Am J Trop Med Hyg, 2013; 89: 875-83.