Stream 1 General Dermatology - Selected Infections

Topics to be covered in the Certificate Course.

Herpes simplex
 Herpes zoster
 Varicella
Other less common Herpes subtypes
Papilloma virus (Warts)
Impetigo and Folliculitis

The common wart is really the human papilloma virus. It is an ubiquitous infection in childhood. Luckily most individuals will develop an immune reaction within a couple of months and then the warts will disappear. However there are a considerable proportion of patients who do not develop normal immune reactions and warts can persist for two to three years. Young warts are more immunogenic than old warts. They have more surface wart markers that the immune system can recognise and mount an immune response to, so I think it is important to actually treat warts early. They can be treated with various topical irritants usually containing mixtures of salicylic acid and lactic acid such as Duofilm wart paint or they can be frozen with liquid nitrogen, again simply to cause some local inflammation and make the viral markers on the surface of the epidermal cell more obvious. Unless an immune reaction occurs the warts will not disappear.

 Note that the HPV typing has reached as high a number as 78, so theoretically you are only immune to that particular serotype when you develop an immune reaction. Luckily most of these serotypes are uncommon. Some are oncogenic and it is important to recognise this because what looks like a wart can subsequently become a squamous cell skin cancer. You do not have to know specifically what HPV types are associated with which tumours. You should just be aware there are a lot of HPV types.
 Note that wart tissue is confined to the epidermis but it expands and pushes the dermis down giving the impression that it has roots that go deep, but it really does not. Proper removal of a wart involving only epidermal tissue should not give rise to scarring. Note though that wart HPV virus extends well beyond the margins of an obvious wart, in fact sometimes up to 5mm. This is why surgical removal is so uniformly unsuccessful or should I say only has about a 20% success rate, simply because not enough tissue is removed. Plantar warts, because of pressure, tend to grow inwards, but again they do not break through the basement membrane. 
Various treatment modalities for warts will be discussed in the Certificate course.. Because there are so many treatments it means that no one is uniformly successful.