text: Bacteria Naturally the cause is bacteria such as staphylococci that are present on the skin. Bacterial colonisation begins in the hair follicles and can cause local cellulitis and inflammation. Myiasis caused by the tumbu fly in Africa usually presents with cutaneous furuncles. Risk factors for furunculosis include bacterial carriage in the nostrils, diabetes mellitus, obesity, lymphoproliferative neoplasms, malnutrition, and use of immunosuppressive drugs.
  Family history
  People with recurrent boils are as well more likely to have a positive family history, take antibiotics, and to have been hospitalised, anemic, or diabetic; they are also more likely to have associated skin diseases and multiple lesions.
  Other
  Other causes include poor immune system function such as from HIV/AIDS, diabetes, malnutrition, or alcoholism. Poor hygiene and obesity have also been linked. It may occur following antibiotic use due to the development of resistance to the antibiotics used. An associated skin disease favors recurrence. This may be attributed to the persistent colonization of abnormal skin with S. aureus strains, such as is the case in persons with atopic dermatitis.
  Boils which recur under the arm, breast or in the groin area may be associated with hidradenitis suppurativa (HS).
  Diagnosis
  Diagnosis is made through clinical evaluation by a physician, which may include culturing of the lesion. Evaluation can further include imaging, such as an ultrasound, to evaluate for formation of an abscess or other complications.