Anyone (including healthy people) is susceptible to getting a fungal nail infection - but some situations make it easier for the fungi to start. If you have a cut or opening near the nail, then the microorganisms can enter that area.
Because your nail bed is the right temperature and moist enough, this provides the right home for fungi to grow and multiply. You can get a fungal infection if you’re older and have certain health conditions that make you more likely to get one.
Diabetes or poor circulation can make a person a prime candidate for nail fungus because of a compromised immune system. Men, more than women, are most likely to get a nail fungus infection.
If you’re consistently exposed to a warm environment, such as living or working in an area that causes a lot of sweating, you can get a nail fungus. A fungus doesn’t need much to get started once you’ve come in contact with one of these microorganisms. Combine some warmth and moisture and you have the perfect breeding ground.
The type of fungi that cause nail infections are very contagious, easily spread on contact - and given the right opportunity, will branch out to other parts of the body. A fungal infection can be annoying, sometimes painful - and it can make you feel embarrassed about how your nails look.
Not wearing shoes in an area where fungi love to be (such as a shower in a gym, a community pool or a water park) can make you a candidate to getting an infection. Just as not wearing shoes in some areas can cause you to get a fungus, wearing the wrong shoes, (such as ones that are too narrow) can provide the right environment for a fungus. So can wearing socks - especially in warm or hot weather.
Your family health history also plays a part. If your family members struggle or have struggled with fungal infections, odds are high that you’ll also have to deal with this health problem, too.
Having another type of tinea fungus elsewhere on the body can also be a culprit that causes nail fungus. Wearing acrylic nails often can be inviting for nail fungus because any separation of the acrylic nail from the natural nail leaves room for warmth and moisture for the fungus to grow.
With the right environment, the warm temperature, the moistness and the food supplied by your body (fungi love the keratin in your nails and this is what it eats) the fungi can happily exist on and in your nails until you seek treatment.
References:
http://www.mayoclinic.org/diseases-conditions/nail-fungus/basics/definition/con-20019319