There are several diagnostic modalities that have been used.
Viral Culture: Vesicles contain the highest number of viral titers during the first 24-48 hours after appearance. However, in clinical practice, recovery of virus from samples is only possible in 7- 25% of patients with active disease.9
Immunofluorescence: Slides prepared from scrapings of lesions can be stained for viral antigens by immunofluorescence. This allows for the identification and typing of isolates.10
Serology: Antibodies develop within the first few weeks of primary infection and persist indefinitely. Serology has limited applications in clinical practice. A four-fold increase in titers occurs between the acute infection and convalesce in primary infection. Serology may be used to differentiate HSV-1 and HSV-2 subtypes for risk stratification of recurrence.11
PCR: Used for diagnosis of HSV infections in other sites like meninges, eyes, etc.
Tzanck smear: Tzanck smears look for cytopathic changes in cells associated with HSV. This technique does not provide a diagnosis; it is rarely done in clinical practice.