Currently, one out of ten people in the US is affected by fungal nail infection. Although anyone can get a nail fungus, Center for Disease Control and Prevention (CDC) mentions some people are more likely to get the nail fungus (https://www.cdc.gov/fungal/nail-infections.html), including those who with following conditions;
The fungus can go into your nail through a small crack on the nail. When you are injured your nail, you are more susceptible to fungal nail infection.
Diabetic people tend to have the lower immune system and low blood circulation.
Weak immune system
Low blood circulation
Athlete foot is a fungal infection on your foot, meaning that your toenail are more likely to be exposed to fungi.
In addition to those conditions above, simply the age can be a factor too – older adults are more prone to get fungal nail infection.
If you have these conditions above, be extra careful for the fungal nail infection. If you notice any changes on your nails, ask doctor immediately.