TY - JOUR
T1 - Money and Microbes
T2 - A Global Systematic Review and Meta-Analysis of Currency Contamination
AU - Appiah, Peter Ofori
AU - Odoom, Alex
AU - Tetteh-Quarcoo, Patience B.
AU - Donkor, Eric S.
N1 - Publisher Copyright:
© The Author(s) 2026. This article is distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 License (https://creativecommons.org/licenses/by-nc/4.0/) which permits non-commercial use, reproduction and distribution of the work without further permission provided the original work is attributed as specified on the SAGE and Open Access pages (https://us.sagepub.com/en-us/nam/open-access-at-sage).
PY - 2026/1/1
Y1 - 2026/1/1
N2 - Money passes through numerous hands daily, creating an ideal medium for the accumulation and transfer of pathogenic microorganisms. Despite this, a comprehensive synthesis of contamination levels on currency is lacking. Aim: This systematic review and meta-analysis assessed the prevalence and types of microbial contamination on money. Methods: A systematic search was conducted for studies published up to December 2024. The review followed the PRISMA guidelines. Pooled prevalence estimates were calculated via a random-effects model. Heterogeneity between studies was assessed via the I² statistic, and sensitivity analyses were performed. Results: A total of 35 studies met the eligibility criteria. The overall pooled prevalence of microbial contamination on money was 12.8% (95% CI: 10.9-14.7). Subgroup analyses revealed pooled prevalence rates of 14.0% (95% CI: 11.1-16.8) for bacteria, 17.0% (95% CI: 12.1-21.8) for fungi, and 9.7% (95% CI: 6.8-12.7) for parasites. Klebsiella spp. 20.3% (95,% CI: 10.4-30.2) and Staphylococcus aureus 19.8% (95% CI: 12.7-26.8) were the predominant bacterial isolates, whereas Aspergillus niger 42.2% (95% CI: 29.1-55.3) was the most frequently identified fungal species, and Entamoeba histolytica was the most frequently identified parasites 18.9% (95% CI: 1.3-36.5). Contamination was greater for paper money 21.3% (95% CI: 13-29.6) than for coins 14.8% (95% CI: 4.3-25.3). Specifically, bacteria were more common on coins 26.4% (95% CI: 8.6-44.2) than on paper money 23.7% (95% CI: 9.5-37.8), whereas parasites were more common on paper money 18.1% (95% CI: 1.2-15.4) than on coins 2.1% (95%, CI: 1.2-3.0). The microbial load of the dirty notes was more 3.0% (95% CI: 2.3-4.1) and that of the newer notes was 2.2% (95% CI: 1.3-3.7). Conclusion: Money is consistently contaminated with potentially pathogenic microbes. Although direct transmission has not been definitively proven, the frequent presence of clinically significant microorganisms on money poses a credible public health risk.
AB - Money passes through numerous hands daily, creating an ideal medium for the accumulation and transfer of pathogenic microorganisms. Despite this, a comprehensive synthesis of contamination levels on currency is lacking. Aim: This systematic review and meta-analysis assessed the prevalence and types of microbial contamination on money. Methods: A systematic search was conducted for studies published up to December 2024. The review followed the PRISMA guidelines. Pooled prevalence estimates were calculated via a random-effects model. Heterogeneity between studies was assessed via the I² statistic, and sensitivity analyses were performed. Results: A total of 35 studies met the eligibility criteria. The overall pooled prevalence of microbial contamination on money was 12.8% (95% CI: 10.9-14.7). Subgroup analyses revealed pooled prevalence rates of 14.0% (95% CI: 11.1-16.8) for bacteria, 17.0% (95% CI: 12.1-21.8) for fungi, and 9.7% (95% CI: 6.8-12.7) for parasites. Klebsiella spp. 20.3% (95,% CI: 10.4-30.2) and Staphylococcus aureus 19.8% (95% CI: 12.7-26.8) were the predominant bacterial isolates, whereas Aspergillus niger 42.2% (95% CI: 29.1-55.3) was the most frequently identified fungal species, and Entamoeba histolytica was the most frequently identified parasites 18.9% (95% CI: 1.3-36.5). Contamination was greater for paper money 21.3% (95% CI: 13-29.6) than for coins 14.8% (95% CI: 4.3-25.3). Specifically, bacteria were more common on coins 26.4% (95% CI: 8.6-44.2) than on paper money 23.7% (95% CI: 9.5-37.8), whereas parasites were more common on paper money 18.1% (95% CI: 1.2-15.4) than on coins 2.1% (95%, CI: 1.2-3.0). The microbial load of the dirty notes was more 3.0% (95% CI: 2.3-4.1) and that of the newer notes was 2.2% (95% CI: 1.3-3.7). Conclusion: Money is consistently contaminated with potentially pathogenic microbes. Although direct transmission has not been definitively proven, the frequent presence of clinically significant microorganisms on money poses a credible public health risk.
KW - currency
KW - microbial contamination
KW - money
KW - public health
KW - systematic review
UR - https://www.scopus.com/pages/publications/105027652283
U2 - 10.1177/11786302251407936
DO - 10.1177/11786302251407936
M3 - Review article
AN - SCOPUS:105027652283
SN - 1178-6302
VL - 20
JO - Environmental Health Insights
JF - Environmental Health Insights
ER -
