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My son had a plantar wart on his foot, which (as I understand it) is caused by a virus which only infects skin cells. Once in the skin cell the virus replicates, but when attacked by the immune system prompts the growth of a hard, thick layer of skin (callus). Warts are caused by a HPV.

Given the wart has infected a skin cell, and skin cells are next to each other in a great big sheet covering the entire human body, why is it that we don't become completely covered in wart? I assume that it's not the immune system keeping the wart at bay, because the original wart isn't defeated and we can get other spot infections elsewhere.

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The Wikipedia page you link to says that they are self-limiting, although it doesn't say why. –  canadianer May 28 at 6:44
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actually there is a person who was completely covered with warts; not as a homogeneous sheet, though. Watched the video on youtube. –  WYSIWYG May 28 at 6:46
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1 Answer 1

Plantar warts grow deep into the skin and slowly [1]. It is a common thing for warts to multiply [1], but because of the slow growth speed, their symptoms [2] and the self clear-up [1] they can't end up by covering the entire skin surface of a previously healthy person.

There are cases of generalized warts in patients with immune deficiency like hypogammaglobulinaemia, impairment of cell mediated immunity [3]. The immune system plays an important role in limiting warts. There is also a case of generalized facial warts in a patient with no other known medical condition [4].

References:

  1. American College of Foot and Ankle Surgeons, Plantar Wart (Verruca Plantaris)
  2. MAYO Clinic, Diseases and Conditions - Plantar warts.
  3. Reid TM, Fraser NG, Kernohan IR. Generalized warts and immune deficiency. Br. J. Dermatol. 1976 Nov;95(5):559-64. PubMed PMID: 1086679.

  4. Semon H. Papillomatosis: Generalized Facial Warts. Proc. R. Soc. Med. 1935 Dec;29(2):90. PubMed PMID: 19990539.

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Your reference for "self clear-up" only indicates that this is a possibility, not a certainty, and doesn't discuss the mechanism. "Generalized warts and immune deficiency" was informative, and suggests that en.wikipedia.org/wiki/Antigenic_variation is the cause of subsequent infections. –  Josh Jun 2 at 23:26
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