Germs love your hands. Do different areas of our hands harbor different germs? Scientific evidence is complex but it seems that different areas of skin in general (and hands) do harbor different types of germs. Our hands are like a sprawling metropolis — and not all neighborhoods are equally safe! Different areas of our hands can harbor different types and amounts of germs: viruses, bacteria, fungi, and even parasites. That is the major reason why we need to clean all areas of our hands during handwashing. But, believe it or not, most people (even healthcare professionals) do not do it well. That is why we embarked on the mission to teach everyone how to BETTER wash their hands. Because it matters for our own health and for the health of those around us. Our approach is innovative, fun and indelible.
Why Different Areas of Hands Have Different Germs?
- Hands’ Anatomy and Use: Some parts of the hand (like palms, fingertips and under fingernails) touch surfaces more often and pick up more germs. Other areas, like between fingers or around the wrist, are more sheltered and can trap moisture, making a cozy environment for bacteria.
- Skin Environment: Different areas have different oils, moisture levels and skin textures, influencing which microbes survive there.
- Habits & Proper Handwashing Technique: While handwashing, people often neglect certain areas (like thumbs, wrists, and in-between fingers), allowing germs to survive and later even spread.
Areas of Hands and the Germs They Harbor
The microbiome of the hands is in constant flux as the hands are a critical vector for transmitting microorganisms between people, pets, inanimate objects and our environments (Sarah L. Edmonds-Wilson et all). Nonetheless, here is a brief attempt to identify certain parts of hands that may harbor different germs.
Fingertips and Under the Nails: The Most Crowded District
This is the most crowded district in the city called hand. Some bugs that can be found on fingertips and under the nails include:
- Bacteria like:
- Staphylococcus aureus — causes skin infections, abscesses, sometimes even deadly bloodstream infections (MRSA).
- Escherichia coli (E. coli) — from fecal matter. E. coli lives in large bowel normally but can become pathogen and cause foodborne illness and urinary tract infections.
- Klebsiella spp. — it is linked to pneumonia and wound infections.
- Viruses:
- Human papillomavirus (HPV) — HPV is a virus that causes warts, often under the nails as well.
- Parasites:
- Pinworm eggs — Pinworm eggs can hide under nails after scratching.
- Fungi:
- Candida albicans is a fungus that causes fungal nail infections.
Fun fact: Artificial nails and long natural nails harbor even more gram-negative bacteria like Pseudomonas. This is especially important to know for those working in the healthcare industry.
Palms: The Grand Central Station
A typical hand surface harbors >150 unique species-level bacterial phylotypes. Palms touch hundreds of surfaces a day, transferring and collecting microbes constantly.
In the metropolitan city metaphor, palms would be the Grand Central Station. Some germs they can contain:
- Viruses:
- Rhinovirus (common cold), influenza (flu), norovirus (stomach flu).
- Bacteria:
- Enterococcus — bacteria which can cause serious infections if transmitted.
- Parasites:
- Giardia lamblia cysts — these are rare, but contaminated surfaces can transfer microscopic parasite cysts onto hands.
In-Between Fingers: The Dark Alleyways
In the metaphoric sense, in between fingers are the dark alleyways. Germs that can live in-between fingers include:
- Fungi:
- Tinea manuum (fungal infection). This tinea is similar to athlete’s foot. Like most fungi, this tinea thrives in warm, moist areas.
- Bacteria:
- Micrococcus spp. Micrococcus is normally harmless bacteria. However, in compromised host (with decreased immune system), it can cause opportunistic infections.
- Viruses:
- Coxsackievirus (hand-foot-and-mouth disease). Like many other enteroviruses, Coxsackie virus likes it want. Logically, one would conclude that they warmest area on hands is in between the fingers. This virus can spread through close contact and contaminated hands and it likes the area in between fingers. Certain subgroups can cause hand-foot-and-mouth disease
Back of Hands: The Suburbs
In the metaphoric sense, back of hands are the suburbs. Backs of hands are often missed during washing, so even low-level contamination can linger. Germs that can live on the back of hands include:
- Bacteria:
- Staphylococcus epidermidis — part of normal skin flora but can cause infections if skin is broken.
- Viruses:
- Less common, but droplets from sneezing/coughing can land here.
Thumbs: The Unsuspecting Highway
In a metaphoric sense, thumbs are the unsuspecting highway. Because thumbs are used for gripping and handling, they are high-contact zones for germs. Germs that can be found on thumbs include:
- Bacteria:
- Same as palms and fingertips (E. coli, Staph aureus).
- Viruses:
- RSV (Respiratory Syncytial Virus) — a major cause of respiratory infections in children.
Wrists: The Outskirts
In a metaphoric sense, the wrists are the outskirts of the city. Wrist washing is rarely taught. This is in particular a major oversight when jewelry is involved (but more on that in another post). Germs that can be found on wrists include:
- Bacteria:
- Normal skin flora (Corynebacterium), but also pathogens like Staph aureus if not cleaned properly.
- Parasites:
- In rare tropical cases: mites (like scabies) can survive at skin surfaces near wrists.
Why Cleaning Every Area Matters
- Complete Germ Removal: Missing one area lets germs survive and multiply.
- Prevention of Spread: Hands are a major route of transmission for diseases (especially respiratory and gastrointestinal illnesses).
- Protection Against Resistant Bacteria: In healthcare and crowded settings, leftover germs may include antibiotic-resistant strains.
The Takeaway: Your hands are mini ecosystems, and different areas are more vulnerable to certain types of microbes. Skipping parts during washing means leaving open doors for infection.
Key parts to target during handwashing: palms, back of hands, in-between fingers, fingertips, fingernails/under nails, thumbs, and wrists. (PBI-FNT-W). This is called washing your hands the right way: The Indelible Way. Use Bubble Beats Handwashing Trainer to learn HOW and develop a healthy habit.
References:
The Hand Microbiome, Bacterial Diversity, and Defining ‘Clean’ in Hand Hygiene. By Kelly M. Pyrek. April 22 2025. https://www.healthcarehygienemagazine.com/the-hand-microbiome-bacterial-diversity-and-defining-clean-in-hand-hygiene/
What Microbes Live On The Hands. By Rachel Wainwright. January 22 2025. https://abchealthonline.com/6605357-what-microbes-live-on-the-hands
Sarah L. Edmonds-Wilson, Nilufar I. Nurinova, Carrie A. Zapka, Noah Fierer, Michael Wilson. Review of human hand microbiome research, Journal of Dermatological Science, Volume 80, Issue 1, 2015, Pages 3-12, ISSN 0923-1811, https://doi.org/10.1016/j.jdermsci.2015.07.006 https://www.sciencedirect.com/science/article/pii/S0923181115300268
N. Fierer, M. Hamady, C.L. Lauber, & R. Knight, The influence of sex, handedness, and washing on the diversity of hand surface bacteria, Proc. Natl. Acad. Sci. U.S.A. 105 (46) 17994-17999, https://doi.org/10.1073/pnas.0807920105 (2008) https://www.pnas.org/doi/10.1073/pnas.0807920105
Hedderwick SA, McNeil SA, Lyons MJ, Kauffman CA. Pathogenic Organisms Associated with Artificial Fingernails Worn by Healthcare Workers. Infection Control & Hospital Epidemiology. 2000;21(8):505-509. doi:10.1086/501794
Price, Lesley et al. Comparing the effectiveness of hand hygiene techniques in reducing the microbial load and covering hand surfaces in healthcare workers: Updated systematic review. American Journal of Infection Control, Volume 50, Issue 10, 1079 – 1090. https://www.ajicjournal.org/article/S0196-6553(22)00067-0/fulltext
WHO Guidelines on Hand Hygiene in Health Care: First Global Patient Safety Challenge Clean Care Is Safer Care. Geneva: World Health Organization; 2009. 7, Transmission of pathogens by hands. Available from: https://www.ncbi.nlm.nih.gov/books/NBK144014/
Dr. Jasminka Vukanovic-Criley MD, FACP, FHM is a multiple award-winning physician, internist, hospitalist, healthcare & education innovator & Associate Clinical Professor of Medicine at UCLA. She is a career mentor & advisor to numerous undergraduate, graduate & postgraduate students & faculty. As a researcher, Dr. Criley received awards from the National Institutes of Health & the U.S. Department of Education Her work focuses on creating research-driven #edtech games & digital media to improve health, civics, science education & promote healthy habits. Dr Criley is also a sought-after speaker & a founding Board member of Physician’s Weekly. She can be reached on X at @criley_md and at www.linkedin.com/in/jasminka-criley-md