Today we will learn about a disease caused by another member of the Herpes virus family. I am referring to Herpes zoster, which, in addition to causing chickenpox, is responsible for a disease known in popular tradition as St. Anthony's fire.
Shingles is a viral disease, which in the most common form manifests itself with a painful rash. This, in general, is limited to only one side of the body and is characterized by the presence of numerous vesicles. As mentioned, Saint Anthony's fire is caused by the varicella-zoster virus (VZV), belonging to the Herpes virus family.We have in fact seen how the same virus is responsible for the appearance of both chickenpox and S. Antonio's fire. Before proceeding, a clarification is necessary. . In other words, only individuals who have had chickenpox can develop shingles. I'll explain. Once chickenpox is contracted, the immune system is unable to completely annihilate the virus, but it pushes it back, forcing it to hide in the cells of the spinal nerve roots. Here, the virus remains inactive and quiet, "hiding" for years or even for a lifetime. However, it may happen that - in some situations that make the body more vulnerable - the virus can reactivate and launch a new attack. In this case, following the path of a nerve, the varicella-zoster virus produces the typical painful rash in the skin area of distribution of the nerve itself.
St. Anthony's fire can occur for various reasons, generally associated with a general decline in the immune system. The awakening of the latent virus can, for example, coincide with a particularly stressful period from a physical or psychological point of view. It is not surprising, therefore, how St. Anthony's fire is observed above all with advancing age or with the use of some immunosuppressive drugs. In addition, it tends to affect more those suffering from debilitating diseases, such as AIDS or cancer. According to medical statistics, one in ten people, most often after the age of 50, will have shingles in their lifetime.
We anticipated that the most characteristic sign of St. Anthony's fire is the appearance of a clustered bullous rash. This rash is accompanied by very intense pain, often associated with a burning and itching sensation. Sometimes, the pain is so intense that even just touching the affected part is intolerable. Similar to cold sores, the onset of shingles is often preceded by a tingling sensation or local numbness. Within a short time, a streak of red dots appears, which then evolves into fluid-filled blisters, similar to lesions of the chickenpox. These bubbles contain a liquid that is first clear and then purulent, and typically appears on only one side of the body. The distribution, in particular, always reflects the path of the sensory nerves affected by the virus. Usually, the rash occurs on the chest or on the back. More rarely, it appears on the face, around the eyes, inside the mouth, on an arm or on a leg. Apart from the typical bullous rash, shingles sometimes occurs with other symptoms, such as fever, chills, headache, stomach pain and general malaise, which may also precede the onset of the rash. Having clarified this, a few days after the appearance of the vesicles we witness their rupture, a moment which coincides with the peak of contagiousness of the disease. Within a few days, 6 or 7 to be exact, the lesions dry up with the formation of scabs.
The fire of Sant'Antonio has a course that varies from ten days to three months. Many cases are resolved with complete recovery, while others unfortunately become chronic resulting in the so-called post-herpetic neuralgia. This complication causes persistent pain weeks, months or even years after the disappearance of the herpes zoster skin lesions.
As for the diagnosis, the symptoms and skin lesions that characterize herpes zoster lend themselves to a fairly unambiguous interpretation. A visual inspection of the affected area by the doctor is therefore generally sufficient. In the presence of suspicious symptoms, it is still possible to resort to some laboratory tests. The most common test is a blood test for immunoglobulins, therefore antibodies, linked specifically to the presence of the varicella-zoster virus (VZV). In other cases, however, it is possible to perform the dosage of the viral particles by PCR, that is, by amplifying their DNA.
Fortunately for many people, Saint Anthony's fire attacks heal and leave only an unpleasant memory. The resolution of herpes zoster is in fact generally spontaneous and often limited to a single episode. However, given the rather annoying disorders it causes, it is useful to use local and systemic treatments to reduce the exanthema and relieve the intensity of pain. In particular, therapy with antiviral drugs, including acyclovir, can reduce the severity of the manifestations and accelerate healing times from herpes zoster. In this regard, an important recommendation to shorten the duration of the manifestations is to start this treatment as soon as possible. To control pain, analgesic and anti-inflammatory drugs can be used, while antibiotics are only useful when the rashes are infected with bacterial superinfection.
As mentioned in the introductory part, a person affected by shingles can only infect a person who has not yet had chickenpox, while contact with people who have already suffered from chickenpox in the past cannot transmit shingles. To prevent normal general hygiene precautions apply to shingles. As this is a viral infection, it is therefore necessary to avoid touching the areas affected by the skin rash and not having direct contact with people affected by the infection or with their clothing. Until the vesicles have turned into scabs, the person is extremely contagious. Recently a specific vaccine has been introduced to vaccinate people from 50 years of age, in order to prevent herpes zoster and post-herpetic neuralgia . However, the vaccine is not able to offer absolute protection and seems to reduce the risk of developing St. Anthony's fire by roughly 50%.
