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Handwashing and diarrhoea in the community

 

Clinical bottom line

Washing hands with soap can dramatically reduce diarrhoeal diseases.


Reference

V Curtis, S Cairncross. Effect of washing hands with soap on diarrhoea risk in the community: a systematic review. Lancet Infectious diseases 2003, 5.

Study

The study looked for English-language publications to the end of 2002 relating handwashing to the risk of infectious intestinal or diarrhoeal diseases in the community. There was a wide search strategy, and there was no limit on geographical setting.

To be included studies had to have an estimate of the risk of not washing hands. Any study design was included, including observational studies. Studies could be in adults or children.

Results

There were 17 reports with 20 different studies. Seven reported on interventions to improve handwashing and ten were observational studies that related handwashing practice to disease rates. ten studies were in Asia, three in Africa, two in Latin America, one in the USA and one in Australia. Nine were in urban settings, five in rural settings, one in both, one in a refugee camp and one did not state a location. Only two studies were randomised.

Table 1 shows the risk estimates for not washing hands and the equivalent reduction in diarrhoeal disease risk. Results were consistent across different subgroups of study.

Table 1: Risks of not washing hands

Studies

Data points

Relative risk

Reduction in risk of diarrhoeal disease (%)

All

20

1.7 (1.4 to 2.2)

43

Intervention studies

10

1.9 (1.3 to 2.7)

47

High methodological quality

6

1.7 (1.5 to 2.0)

42

Soap only

19

1.8 (1.4 to 2.2)

44

Severe outcomes only

9

1.9 (1.4 to 2.7)

48

Shigellosis only

2

2.4 (1.6 to 3.7)

59

The two studies in Western countries (USA and Australia) were both conducted in children, with interventions for carers about washing hands after caring for children, especially after toileting. Both showed similar reductions in risk with handwashing.

Comment

The authors comment on the low quality of some of the studies, and point out the difficulties of conducting randomised trials. They also point out that the estimated annual death rate from diarrhoeal diseases in 2.2 million. They estimate that up to 1 million of these could be prevented by adequate handwashing. Though most of these deaths are in less developed countries where facilities are poor, the lesson still holds for developed countries like the UK.