Who to Test

Clinicians should make testing decisions based on individualized risk factors and patient preferences. Although there is some disagreement among experts as to which groups benefit most from serologic (blood) testing, there is general agreement that testing is significantly underutilized. As indicated by the clinical scenarios in the table on page 4, a wide range of patients are likely to benefit from the use of swab and/or type-specific serologic tests (Immunoglobulin G, or IgG, antibody tests).

Swab test options include viral culture and the more sensitive polymerase chain reaction (PCR). These tests are most sensitive when obtained within 3-4 days of the start of an outbreak. Recently approved HSV DNA tests are also available for symptomatic patients. These new tests are highly sensitive, distinguish between HSV-1 and HSV-2, and can yield results in 1-2 days.

Type-specific serologic tests detect the presence of antibodies to HSV, and can be performed in the presence or absence of lesions. Serologic tests cannot determine the anatomic location of HSV disease (i.e., genital versus non-genital). However, there is general agreement that a positive HSV-2 serologic test indicates genital infection with a high degree of certainty. HSV-1 serologic tests are less helpful in determining the site of infection. More than half of the U.S. population has HSV-1 antibodies by late adolescence (up to and including 29 years of age), primarily due to non-genital infection, thus HSV-1 testing may be less useful than HSV-2 testing.8

In general, patients with low or no likelihood of infection should not be tested. This includes children and those who have not had genital-to-genital or oral-to-genital sexual contact.