Skip Navigation Links
Centers for Disease Control and Prevention
 CDC Home Search Health Topics A-Z
National Center for HIV/AIDS, Viral Hepatitis, STD and TB Prevention
  Division of Sexually Transmitted Diseases
    Program and Training Branch
STD Prevention STD Training Home Links Contact Us Glossary 
STD Prevention
Self-Study Modules
Herpes Simplex Virus (HSV)
Course Objective
Line separator
Target audience
Line separator
Continuing education
Line separator
Line separator
Pathogenesis and microbiology
Line separator
Clinical manifestations and sequelae
Line separator
Diagnostic methods
Line separator
Patient management / treatment
Line separator
Patient counseling and education
Line separator
Partner management
Line separator
Case study
Line separator
Line separator

Self-Study STD Module - Genital Herpes Simplex Virus (HSV) Infection

Diagnostic Methods

Clinical diagnosis of HSV is insensitive and nonspecific; therefore, the clinical diagnosis of genital herpes should be confirmed by laboratory testing. Many infected persons do not experience the multiple vesicular or ulcerative lesions typical of genital herpes.

There are two main types of lab tests used for confirmatory diagnosis:

  • Virologic tests
  • Type-specific serologic tests

Virologic Tests

Viral culture is considered the gold standard for HSV diagnosis. It is the preferred test if genital ulcers or other mucocutaneous lesions are present. Viral culture is highly specific (>99%), but sensitivity depends on stage of lesion and proper collection technique and declines rapidly as lesions begin to heal. Viral recovery for early vesicles is about 90%, for ulcers about 70%, and for crusted lesions about 30%.

Culture is more commonly positive in primary infection (80%90%) than with recurrences (30%). Most cultures will be positive within 24-72 hours.

Antigen detection is fairly sensitive (>85%) in symptomatic shedders and may be better than culture for detecting HSV in healing lesions. Antigen detection is rapid (2-12 hours) and highly specific, but false positives can occur.  The direct fluorescent antibody (DFA) test distinguishes between HSV-1 and HSV-2, while other virologic tests do not.

Cytology (Tzanck or Pap) identifies typical HSV-infected cells (multi-nucleated giant cells and eosinophilic inclusion bodies) in exfoliated cells or biopsies. Cytologic detection of cellular changes resulting from HSV infection is insensitive (50%) and nonspecific. It should not be relied upon for HSV diagnosis, either for genital lesions (i.e., Tzanck preparation) or for cervical Pap smears.

Polymerase Chain Reaction (PCR) assays for HSV DNA are highly sensitive and specific, however PCR tests are not FDA-cleared for testing of genital specimens, are not widely available, and may lack standardization across laboratories. PCR is the preferred test for detecting HSV in spinal fluid.

The following table shows a comparison of the virologic tests

Click here for a Study Question

Page 8 of 20 BackStatusStatusNext

Page last modified: June 3, 2009
Page last reviewed: June 3, 2009

Content Source: Division of STD Prevention, National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention

STD Home
| STD Index

CDC Home | Search | Health Topics A-Z

Centers for Disease Control and Prevention
National Center for HIV/AIDS, Viral Hepatitis, STD and TB Prevention
     Division of Sexually Transmitted Diseases Prevention