Potential risk factors and causes of fungal infection include the following:

• Compromised immune system. Yeast infections may occur when the immune system is weakened due to illness, disease (e.g., diabetes), stress or certain medications (e.g., immunosuppressants). A weak immune system can disturb the natural balance of skin organisms and allow one type to overgrow.
  
  
• Use of antibiotics. Antibiotic use may also cause yeast infections by killing the natural bacteria that keep the yeast growth under control.
  
  
• Tropical climate. Fungi grow best in regions that are warm and humid, so people living in such areas may be more prone to fungal infection.
  
  
• Obesity. People who are obese may also be at higher risk because they have many skin folds to encourage fungal growth.
  
  
• Heredity. Some individuals may be more susceptible to fungal skin infections due to genetic predisposition.
  
  
• Pre-existing injury or infection. People are more likely to develop fungal infections when they have pre-existing skin injury, nail injury or infection.
  
  
• Poor hygiene. A lack of hygiene can promote the growth of fungus on the skin and nails.

Continuous exposure to water may predispose an individual to fungal infections, as well as manicures and pedicures. 

In addition, dermatophyte fungal infections may be caused by direct contact with infected humans, animals, contaminated objects or soil.