However, herpes simplex virus (HSV) can occasionally produce a rash in such a pattern (zosteriform herpes simplex).When the rash is absent (early or late in the disease, or in the case of zoster sine herpete), shingles can be difficult to diagnose. Apart from the rash, most symptoms can occur also in other conditions. Laboratory tests are available to diagnose shingles. The most popular test detects VZV-specific IgM antibody in blood; this appears only during chickenpox or shingles and not while the virus is dormant. In larger laboratories, lymph collected from a blister is tested by polymerase chain reaction (PCR) for VZV DNA, or examined with an electron microscope for virus particles. Molecular biology tests based on in vitro nucleic acid amplification (PCR tests) are currently considered the most reliable. Nested PCR test has high sensitivity, but is susceptible to contamination leading to false positive results. The latest real-time PCR tests are rapid, easy to perform, and as sensitive as nested PCR, and have a lower risk of contamination. They also have more sensitivity than viral cultures. Differential diagnosis
Shingles can be confused with herpes simplex, dermatitis herpetiformis and impetigo, and skin reactions caused by contact dermatitis, candidiasis, certain drugs and insect bites. Prevention
Shingles can be prevented by the chickenpox vaccine if the vaccine is administered before the individual gets chickenpox. If primary infection has already occurred, there are shingles vaccines that reduce the risk of developing shingles or developing severe shingles if the disease occurs.
Symptoms include hearing loss and vertigo (rotational dizziness).Shingles may occur in the mouth if the maxillary or mandibular division of the trigeminal nerve is affected, in which the rash may appear on the mucous membrane of the upper jaw (usually the palate, sometimes the gums of the upper teeth) or the lower jaw (tongue or gums of the lower teeth) respectively. Oral involvement may occur alone or in combination with a rash on the skin over the cutaneous distribution of the same trigeminal branch. As with shingles of the skin, the lesions tend to only involve one side, distinguishing it from other oral blistering conditions. In the mouth, shingles appears initially as 1–4 mm opaque blisters (vesicles), which break down quickly to leave ulcers that heal within 10–14 days. The prodromal pain (before the rash) may be confused with toothache. Sometimes this leads to unnecessary dental treatment. Post-herpetic neuralgia uncommonly is associated with shingles in the mouth. Unusual complications may occur with intra-oral shingles that are not seen elsewhere. Due to the close relationship of blood vessels to nerves, the virus can spread to involve the blood vessels and compromise the blood supply, sometimes causing ischemic necrosis. Therefore, oral involvement rarely causes complications, such as osteonecrosis, tooth loss, periodontitis (gum disease), pulp calcification, pulp necrosis, periapical lesions and tooth developmental anomalies. Disseminated shingles
In those with poor immune function, disseminated shingles may occur (wide rash). It is defined as more than twenty skin lesions appearing outside either the primarily affected dermatome or dermatomes directly adjacent to it.