Herpes zoster, colloquially known as shingles, is the
reactivation (from the general area of the spinal cord) of
varicella zoster virus (VZV, primary infection of which leads to
chickenpox), one of the Herpesviridae group, leading to a crop of
painful blisters over the area of a dermatome.
The earliest symptoms of shingles include headache, sensitivity to
light, flu-like symptoms without fever, as well as itching,
tingling, and extreme pain where the rash is developing. Often,
pain is the first symptom. This pain can be characterized as
stinging, tingling, numbing, or throbbing, and can be pronounced
with quick stabs of intensity. Then 1-3 crops of red lesions
develop, which gradually turn into small blisters filled with
serous fluid. A general feeling of unwellness often occurs. In some
cases, the rash does not form blisters, but has an appearance much
like urticaria ("hives").
Shingles cannot be passed from one person to another. However, the
virus that causes shingles, VZV, can be spread from a person with
active shingles to a person who has never had chickenpox through
direct contact with the rash. The person exposed would then develop
chickenpox, not shingles. The virus is not spread through sneezing,
coughing or casual contact. A person with shingles can spread the
disease when the rash is in the blister-phase. Once the rash has
developed crusts, the person is no longer contagious. A person is
not infectious before blisters appear or with post-herpetic
neuralgia (pain after the rash is gone).
Chickenpox virus can remain dormant for decades, and does so inside
the ganglion near the spinal cord. As the virus is reactivated it
spreads down peripheral nerve fibers and produces intense pain. The
blisters therefore only affect one area of the body and do not
cross the midline. They are most common on the torso, but can also
appear on the face (where they are potentially hazardous to vision)
or other parts of the body.
Outbreaks occur for many different reasons, most of which are a
result of events which depress the immune system, such as aging,
severe emotional stress, severe illness or long-term use of
corticosteroids. There have been recorded cases of outbreaks
occurring due to unmanaged stress or other stresses to the skin
such as pinching in more sensitive areas of the skin
(nipples, ears, and underarms), scratching, or
biting.
The causative agent for herpes zoster is varicella zoster virus
(VZV). Most people are infected with this virus as a child, as it
causes chickenpox. The body eliminates the virus from the system,
but it remains dormant in the ganglia adjacent to the spinal cord
(called the dorsal root ganglion) or the ganglion semilunare
(ganglion Gasseri) in the cranial base.
Generally, the immune system suppresses reactivation of the virus.
In the elderly, whose immune response generally tends to
deteriorate, as well as in those patients whose immune system is
being suppressed, this process fails. (Some researchers speculate
that sunburn and other, unrelated stresses that can affect the
immune system may also lead to viral reactivation.) The virus
starts replicating in the nerve cells, and newly formed viruses are
carried down the axons to the area of skin served by that ganglion
(a dermatome). Here, the virus causes local inflammation in the
skin, with the formation of blisters.
The pain characteristic of herpes zoster is thought to be due to
irritation of the sensory nerve fibers in which the virus
reproduces.[
Stages-
1)Back or underarm pain and small rash spots appear
2)Rash (itchy for some) spreads around the body
3)More pain develops
4)Bubbles filled with fluid pop up
5)After 4-5 days pain is gone and bubbles turn dark purple and peel
off
