From the Guidelines
Diagnosing shingles is primarily based on the clinical presentation of a painful, blistering rash that follows a dermatomal distribution on one side of the body, with laboratory tests such as viral culture, PCR, or DFA testing used to confirm the diagnosis. The diagnosis of shingles typically involves a healthcare provider examining the characteristic rash and evaluating symptoms, including pain, burning, tingling, or itching in the affected area for 1-5 days before the rash appears 1.
Key Diagnostic Features
- A painful, blistering rash that follows a dermatomal distribution on one side of the body
- Red patches that progress to fluid-filled blisters that eventually crust over
- Pain, burning, tingling, or itching in the affected area for 1-5 days before the rash appears
- A thorough medical history, as shingles only occurs in people previously infected with chickenpox or who received the chickenpox vaccine
Laboratory Tests
- Viral culture of the fluid from blisters
- PCR testing of the fluid from blisters
- DFA (direct fluorescent antibody) testing of skin lesion samples
- Blood tests for varicella-zoster virus antibodies, particularly in cases without a clear rash 1
Importance of Early Diagnosis
Early diagnosis is crucial as antiviral medications are most effective when started within 72 hours of rash onset, helping to reduce the severity and duration of symptoms and lower the risk of complications like postherpetic neuralgia. According to the practice guidelines for the diagnosis and management of skin and soft tissue infections, high-dose IV acyclovir remains the treatment of choice for VZV infections in compromised hosts, while oral acyclovir, famciclovir, and valacyclovir are beneficial for VZV infections in otherwise healthy hosts 1.
From the Research
Diagnosis of Shingles
- Shingles is diagnosed clinically by recognition of the distinctive, painful vesicular rash appearing in a unilateral, dermatomal distribution 2
- The rash is usually unilateral, confined to a single dermatome, and typically progresses to clear vesicles that become cloudy and crust over in seven to 10 days 3
- Patient history is critical in reaching a diagnosis, not only to manage the outbreak effectively, but also to prevent severe complications such as dissemination of the virus into the central nervous system 4
- Laboratory testing, including polymerase chain reaction, can confirm atypical cases 2
Clinical Presentation
- Patients may present with malaise, headache, low-grade fever, and abnormal skin sensations for two to three days before the classic maculopapular rash appears 3
- The intensity of the pain can vary, and it is typically confined to a single dermatome 5
- Postherpetic neuralgia is the most common complication, occurring in about one in five patients, and is defined as pain in a dermatomal distribution sustained for at least 90 days after acute herpes zoster 3