HSV is a common STD worldwide. Although HSV type 2 (HSV-2) remains the main causative agent for the preponderance of virologically confirmed infections, HSV type 1 (HSV-1) is associated with an increasing proportion of cases of genital herpes.
HSV-1 generally infects the mucous membrane of the eye, mouth, and mucocutaneous junctions of the face, and it is also one of the most common causes of severe sporadic encephalitis in adults.
HSV-2 is usually associated with mucocutaneous genital lesions. Recently, an increasing number of genital herpes infections have been shown to be due to HSV-1. HSV-1 causes primary episodes indistinguishable from HSV-2, but with less frequent recurrence.
Pregnant women who develop genital herpes near the time of delivery are at high risk for transmission to the neonate. Transmission of HSV infection to neonates is associated with high morbidity and mortality rates if untreated.
Because HSV-1 and HSV-2 share common antigenic determinants, antibody detected against one viral type may cross-react with the other viral type. Truly type-specific antibody tests are based on glycoprotein G1 (from HSV-1) and glycoprotein G2 (from HSV-2), as these proteins exhibit very limited homology. The CDC recommends the use of type-specific glycoprotein G based assays when serology is performed.
Other names: Herpes simplex serology, HSV antibody titer.
Normal range: Negative.
Use
To diagnose a patient with a history of genital lesions who did not have a diagnostic workup, diagnose a past or present HSV infection in a patient with an atypical presentation, determine susceptibility of a sexual partner of a patient with documented genital HSV infection, and identify asymptomatic HSV infection in pregnant women who are at risk for shedding at the time of delivery with potential transmission to the infant or help predict the risk of recurrence.
Interpretation
HSV IgM " �combined positive result (i.e., the presence of IgM class HSV 1 and/or 2 antibodies) indicates recent infection. The presence of HSV 1 and/or 2 antibodies may indicate a primary or reactivated infection but cannot distinguish between them.
The IgG antibody assay differentiates between type 1 and 2 HSV antibodies. The presence of IgG antibodies specific for HSV type 1 or 2 indicates previous exposure to the corresponding serotype of the virus.
Limitations
A clinical diagnosis of genital herpes should be confirmed with laboratory testing. The diagnosis can be made by viral culture, PCR, DFA, Tzanck preparation, and type-specific serologic tests. The choice of test varies with the clinical presentation.
Both the CDC and the International Union against Sexually Transmitted Infections (IUSTI) recommend using molecular methods for typing all patients with first-episode genital herpes.
The prevalence of HSV antibodies can vary depending on a number of factors such as age, gender, geographic location, socioeconomic status, race, sexual behavior, testing method used, specimen collection and handling procedures, and the clinical and epidemiologic history of individual patients.
A negative result does not necessarily rule out a primary or reactivated infection, since specimens may have been collected too early in the course of disease, when antibodies have not yet reached detectable levels, or too late, after IgM levels have declined below detectable levels.
False-positive test results may occur in patients infected with EBV, in primary or reactivated varicella virus infection, and in the presence of rheumatoid factor antibodies.