Onychomycosis of the fingernail is most often caused by Candida albicans, a species of yeast that’s also known as an opportunistic fungal pathogen. This type of nail fungus usually affects swimmers and divers, since their hands are submerged in water for long periods of time. Onychomycosis of the fingernail typically starts by affecting the soft tissue around the nails and then progresses to the nail plate where it causes a secondary infection. Candida species account for most of the yeast-causing onychomycosis cases, and Candida albicans specifically is responsible for 5% of all onychomycosis cases.
As for non dermatophyte molds, Scytalidium, Scopulariopsis, and Aspergillus are the mold generations that most often lead to onychomycosis. Scytalidium is particularly common in tropical and subtropical climates, but will also follow sufferers to more temperate climates if they relocate after being infected. Nondermatophyte molds are most often seen in elderly people above the age of 60 since the nail’s ability to fight off infection weakens with age.
Risk factors for onychomycosis include living in a warm climate or otherwise humid environment, being of older age or in poor health, participating in physical activities, perspiring heavily, having a family history of nail fungus, being immunosuppressed, wearing occlusive footwear, and partaking in communal bathing. Immunosuppression may be caused by HIV, radiotherapy, chemotherapy, or other diseases that weaken the body’s immune response and impact its ability to fight infections. Occlusive footwear refers to unventilated sneakers and boots, often made of rubber or vinyl, which create a warm and moist environment for fungi to thrive.
In terms of age, onychomycosis occurs in 20% of people above the age of 60 and in 50% of people above the age of 70, compared to 10% of the general population. It is believed that elderly people are more affected by onychomycosis due to poor blood circulation and the decreased defense against nail fungus that comes with old age. Furthermore, their nails are thicker and grow at a slower rate than younger individuals. Lastly, elderly individuals will have been exposed to the fungi for longer periods of time, giving it more of a chance to grow and spread throughout the body.
In order to prevent fungal nail infections, it is recommended that you throw out old shoes, wear clean socks daily, keep your feet clean and dry, wear shoes in public showers, and treat cases of athlete’s foot before it has a chance to spread to the nails. On the other hand, it is recommended that you do not share towels or shoes, do not share nail scissors or clippers, and avoid shoes that make your feet feel hot and sweaty. This is because onychomycosis tends to develop when the feet are warm and damp for long stretches of time.