Herpes simplex virus (HSV) occurs worldwide and produces a variety of clinical manifestations, ranging from mild stomatitis to fatal disease. Herpes simplex virus type 2 (HSV-2) causes recurrent genital herpes episodes more often than herpes simplex virus type 1 (HSV-1), although HSV-1 is responsible for a growing number of genital herpes cases.
Key Points
Herpes simplex virus (HSV) infections are extremely common worldwide. The herpes simplex viruses comprise two distinct types of DNA viruses: herpes simplex virus type 1 (HSV-1) and herpes simplex virus type 2 (HSV-2). While HSV subtyping is available, typing is not required for treatment. Treatment for HSV-1 and HSV-2 infections is the same.
Indications for HSV Testing
- Sexually transmitted infection – seronegative individuals are at risk of acquiring infection from seropositive partners
- HSV-1
- Usually transmitted via nonsexual route
- An increasing proportion of genital herpes is due to HSV-1
- HSV-2
- Majority of persons positive for HSV-2 have not been diagnosed with genital herpes
- Individuals with HSV-2 can have mild or unrecognized disease and may shed virus from genital area intermittently
- HSV-2 infection increases the risk of acquiring HIV infection (refer to STDs and HIV – CDC Fact Sheet)
- HSV-1
- Transmission from mother to neonate
- First-time (primary) infection of woman during pregnancy – increases the risk of transmitting virus to neonate during delivery
- Most neonatal infections are acquired intrapartum
- Reinfection with HSV – rare, but dormant virus can be reactivated
- Prognostic indicator and guide for treatment in transplant patients – majority of HSV infections in transplant recipients result from reactivation of latent virus, especially during early posttransplant period and periods of severe immunosuppression
- Central nervous system (CNS) infections
- HSV-related meningitis – generally benign and controlled with antivirals
- Untreated HSV-related encephalitis – >70% fatality rate
- Antiviral susceptibility for HSV (eg, acyclovir)
HSV Typing
- Typing is unreliable and potentially clinically insignificant in many cases due to cross-reactivity between the 2 HSV types
- Typing may be useful epidemiologically, for patient counseling regarding disease acquisition, and for some assistance with prognosis (CDC, 2014)
- HSV subtype does not affect choice of treatment
- Early false negative results may occur; type-specific antibody testing may not be positive until 2-3 months postinfection
- If pursuing subtyping, HSV-1/-2 glycoprotein G (gG) antigen serology testing is recommended
- “Type-specific” antibody testing
- Does not detect cross-reacting antibodies
- Provides more accurate serological assessment of HSV-1/HSV-2
- IgM testing – limited clinical utility; not reliable for diagnosis of genital lesions or neonatal herpes (CDC, 2014)
Laboratory Testing for HSV
HSV infection can be confirmed by direct detection of the virus, detection of antibodies to HSV, or immunohistochemical testing
Test Methodology | Description |
---|---|
NAAT (PCR) testing for viral DNA |
Rapid diagnostic testing. Preferred method for CSF testing and neonates. May detect asymptomatic HSV shedding. High sensitivity and specificity. Typing is included in some reflex tests. |
Viral culture |
Traditional gold standard test for identifying acute HSV infection in active lesions (eg, vesicles, ulcers, inflamed mucous membranes). Molecular testing (eg, PCR) generally preferred High specificity but low sensitivity, especially for recurrent and healing lesions. High rate of false negatives – sensitivity declines rapidly as lesions begin to heal. More often positive in primary infection (80-90%) than recurrences (30%) (CDC, 2014). Typing is included in some reflex tests. |
Antigen detection by DFA |
Rapid diagnostic test with culture backup for negative DFA results. Test may be helpful in identifying acute HSV infection in active lesions. Molecular testing is generally preferred. Lower sensitivity compared to PCR Typing is not included in this testing. |
Cytology |
Not recommended. |
CSF, cerebrospinal fluid; DFA, direct fluorescent antibody; NAAT, nucleic acid amplification test; PCR, polymerase chain reaction |
Test Methodology | Description |
---|---|
HSV-specific glycoprotein G2 (HSV-2) and glycoprotein G1 (HSV-1) |
Glycoprotein G-based type specific test is acceptable for HSV serologic diagnosis (CDC, 2015). May be useful for the following:
|
IgG testing |
Sensitivity varies; false-negative results might be more frequent at early stages of infection. Type-specific HSV IgG antibodies may require 3-6 months to form. Follow-up testing is required to confirm negative IgG glycoprotein result in context of positive HSV types 1 or 2 antibody results. |
IgM testing |
Not recommended; lacks adequate predictive value for acute infection (CDC, 2015). |
aHSV-1 and -2 are closely related antigenically and high cross-reactivity exists between the 2 common antigens, which may affect the accuracy of antigen-based typing tests. Serology tests that use HSV-1 or -2 glycoprotein G (gG) antigens are considered “type-specific” antibody tests and do not detect cross-reacting antibodies. Thus, they provide a more accurate serological assessment of whether the HSV is type 1 or 2. Because glycoprotein antibodies may require up to 3 months to form, follow-up testing is recommended to confirm a negative IgG glycoprotein in the context of positive HSV-1 or -2 antibody results. |
Test Methodology | Description |
---|---|
Antiviral susceptibility testing |
Determine susceptibility to treatment in immunosuppressed patients (eg, patients with HIV or organ transplant). |
Test Methodology | Description |
---|---|
Immunohistochemical staining of FFPE prepared tissues/cells |
Not commonly ordered. May be considered if tissue histology is suspicious for HSV. |
FFPE, formalin-fixed paraffin-embedded |
Diagnosis
Indications for Testing
- Genital or oral ulcerative or vesicular lesions
- Central nervous system (CNS) infections
- Unidentified encephalitis
- Encephalitis with focal neurologic symptoms
- Herpes simplex virus (HSV)-related meningitis
- Corneal ulcer
- Transmission from mother to neonate – evaluate first-time (primary) infection of woman during pregnancy
- Prognostic indicator and guide for treatment in transplant patients – majority of HSV infections in transplant recipients result from reactivation of latent virus, especially during early posttransplant period and periods of severe immunosuppression
- Antiviral susceptibility for HSV (eg, acyclovir, foscarnet)
Criteria for Diagnosis
Genital herpes HSV case definition (CDC, 1996)
Laboratory Testing
- Refer to Key Points for laboratory testing options
- CNS disease – consider multiple panel testing on cerebrospinal fluid (CSF) and serum to rule out other viral illnesses (eg, varicella-zoster virus [VZV], mumps)
Histology
Refer to Key Points
Prognosis
- Following active infection, HSV establishes latent infection that can be reactivated
- Neonates
- Better prognosis with herpes simplex virus type 1 (HSV-1) ocular, oral, cutaneous disease
- Less neurologic morbidity with HSV-1 encephalitis
- More sequelae from HSV-1 disseminated disease
Differential Diagnosis
- Oral disease
- Acute necrotizing ulcerative gingivitis
- Aphthous ulcers
- Behçet syndrome
- Erythema multiforme
- Enterovirus
- Herpangina (coxsackievirus)
- Impetigo
- Pemphigus
- Stevens-Johnson syndrome
- Genital disease
- Atopic dermatitis
- Behçet syndrome
- Erosive lichen planus
- Haemophilus ducreyi
- Treponema pallidum
- Urethritis
- Skin lesions
- Finger lesions – paronychia
- Congenital disease
- VZV
- Rubella
- Toxoplasma gondii
- Treponema pallidum
- Parvovirus B19
- Cytomegalovirus
Screening
Serologic screening in asymptomatic persons not recommended (U.S. Preventive Services Task Force [USPSTF], 2016; Choosing Wisely, 2018)
Background
Epidemiology
- Prevalence (CDC, 2014)
- Herpes simplex virus type 1 (HSV-1) – ~60% seropositivity in U.S. adults; >90% positivity in undeveloped countries
- Herpes simplex virus type 2 (HSV-2) – ~16% seropositivity in persons aged 14 to 49 years in the U.S.
- Age
- 33% of cases <20 years
- 50% of cases >50 years
- Sex – M<F (HSV-2)
- Transmission
- HSV-1
- Predominantly oral
- Genital herpes cases increasing
- Vertical transmission
- HSV-2
- Predominantly sexually (can occur during asymptomatic periods)
- Vertical transmission (perinatally)
- HSV-1
Organism
- Double-stranded DNA virus of the Herpesviridae family
- HSV-1 – majority of nongenital HSV infections
- HSV-2 – cause of genital infections in >80% of patients
- Biological features unique to herpes virus
- Latency
- Reactivation
Clinical Presentation
- Only 10-30% of new infections are symptomatic
- Primary infections are usually longer in duration than reactive infections
- HSV-2 causes recurrent genital herpes episodes more often than HSV-1
- Genital herpes (primary and recurrent)
- Increases risk for acquiring HIV
- Usually presents as symptomatic and painful genital ulcer
- Genital herpes (primary and recurrent)
- Pregnancy
- Disease has higher rate of dissemination
- More commonly associated with visceral involvement
- Clinical symptoms are widespread and depend on clinical site, age, and immune status of host
- Gingivostomatitis – widespread oral ulcers with lymphadenopathy (submandibular, cervical)
- Recurrent herpes labialis – erythematous papules and vesicles on lips
- Keratitis – eye pain, light sensitivity, corneal dendritic ulcers (can lead to blindness)
- Conjunctivitis – increases risk of keratitis
- Herpes gladiatorum – vesicular skin eruptions usually in face, ears, and neck areas
- Eczema herpeticum – dissemination of oral herpes into a previously abnormal skin area (burns, atopic dermatitis)
- Herpes sycosis – vesiculopapular lesions in beard area
- Herpetic whitlow – vesicular eruption located on pulp of distal phalanges of hands
- Aseptic meningitis and recurrent meningitis (Mollaret meningitis)
- Occurs as a complication of HSV-1 or HSV-2 primary infection
- Seizures may be first presentation
- Visceral herpes (esophagitis, pneumonitis, hepatitis) – more common in immunocompromised patients
- Meningitis/encephalitis – associated with focal neurologic findings
- Neonatal herpes – infection may be acquired in utero, intrapartum, or postnatally
- Encephalitis
- Congenital – microcephaly, hydrocephalus, chorioretinitis, cutaneous vesicular lesions, myocarditis, skin lesions
- Proctitis – most common in homosexual men
- Erythema multiforme – secondary HSV is one of the most common causes
Prevention
- Barrier contraception and daily suppressive therapy recommended to prevent partner infection
- Pregnant women not infected with HSV-2 should be advised to avoid intercourse during the third trimester with infected partner
ARUP Laboratory Tests
Preferred test for detecting herpes simplex virus (HSV) infection in cerebrospinal fluid (CSF), neonates, or when rapid diagnostic test for suspected HSV infection is necessary
Qualitative Polymerase Chain Reaction
Detect and genotype HSV types 1 and 2
Qualitative Polymerase Chain Reaction
Genotype HSV types 1 and 2
Negative result does not rule out presence of PCR inhibitors in patient specimen or test-specific nucleic acid in concentrations below level of detection by this test
Qualitative Polymerase Chain Reaction
Traditional gold standard test for identifying acute HSV infection in active lesions (eg, vesicles, ulcers, inflamed mucous membranes)
Molecular testing is generally preferred; refer to HSV by PCR
Cell Culture/Immunoassay
Detect HSV by viral culture and differentiate types 1 and 2; molecular testing generally preferred
Cell Culture/Immunoassay
Reflex pattern: if culture is positive for HSV, then HSV typing will be added
Rapid diagnostic test with culture backup for negative direct fluorescent antibody (DFA) results
Test may be helpful in identifying acute HSV infection in active lesions (eg, vesicles, ulcers, inflammation of mucous membranes)
Molecular testing is generally preferred; refer to HSV by PCR
Sensitivity of DFA methodology dependent on adequacy of specimen; if there are fewer than 20 cells, DFA result will be reported as "sample inadequate"
Direct Fluorescent Antibody Stain/Cell Culture
Reflex pattern: if DFA is negative or inadequate, then HSV culture will be added
Aid in the histological diagnosis of HSV
Stained and returned to client pathologist; consultation available if needed
Immunohistochemistry
In the absence of active lesions, this is the preferred serology test for diagnosing HSV infection
Semi-Quantitative Chemiluminescent Immunoassay
Preferred testing for HSV when recent acquisition of HSV is suspected
Because glycoprotein antibodies may require 3-6 months to form, follow-up testing is recommended to confirm a negative IgG glycoprotein result in the context of positive HSV type 1 or 2 antibody results
Refer to HSV IgG glycoprotein types 1 and 2 antibody test
Semi-Quantitative Chemiluminescent Immunoassay
Detect HSV resistance to acyclovir
Cell Culture, Susceptibility
Detect HSV resistance to foscarnet sodium
Cell Culture/Susceptibility
Differentiate herpes simplex virus (HSV) types 1 and 2 based on cultured virus isolates
For culture combined with typing, refer to the HSV culture reflex test
Cell Culture/Immunofluorescence
Rapid diagnostic test with culture backup that may be helpful when uncertain whether a lesion is due to varicella-zoster virus (VZV) or HSV
Direct Fluorescent Antibody Stain/Cell Culture
For suspected and/or active HSV infection, molecular testing is preferred; refer to HSV by polymerase chain reaction (PCR)
If pursuing antibody testing, refer to HSV types 1 and 2 IgG glycoprotein cerebrospinal fluid (CSF) testing
If acute HSV infection is suspected, molecular testing is preferred; refer to HSV by PCR
Semi-Quantitative Chemiluminescent Immunoassay
Not a first-line test for HSV 2 typing
Semi-Quantitative Enzyme-Linked Immunosorbent Assay
Order in conjunction with HSV type 1 glycoprotein antibody test
Semi-Quantitative Chemiluminescent Immunoassay
Not a stand-alone test
Order in conjunction with HSV type 2 glycoprotein antibody test
Because glycoprotein antibodies may require 3-6 months to form, follow-up testing is recommended to confirm a negative IgG glycoprotein result in the context of positive HSV types 1 or 2 antibody results
Semi-Quantitative Chemiluminescent Immunoassay
Not a stand-alone test
Molecular testing is preferred; refer to HSV by PCR test
Semi-Quantitative Enzyme-Linked Immunosorbent Assay
Semi-Quantitative Enzyme-Linked Immunosorbent Assay
Not recommended for HSV testing; IgM lacks adequate predictive value for acute infection
If pursing antibody testing, preferred test is HSV types 1 and 2 IgG glycoprotein antibodies
If acute HSV infection is suspected, molecular testing is preferred; refer to HSV by PCR
Semi-Quantitative Chemiluminescent Immunoassay/Semi-Quantitative Enzyme-Linked Immunosorbent Assay
Reflex pattern: if HSV 1 and/or 2 IgG is 1.10 IV or greater, then HSV 1 gG-specific IgG and HSV 2 gG-specific IgG will be added
Semi-Quantitative Enzyme-Linked Immunosorbent Assay/Semi-Quantitative Chemiluminescent Immunoassay
Not recommended for HSV testing; lacks adequate predictive value for acute infection
Preferred testing is HSV by PCR
Semi-Quantitative Chemiluminescent Immunoassay/Semi-Quantitative Enzyme-Linked Immunosorbent Assay
Reflex pattern: if HSV 1/2 IgG, CSF is greater than or equal to 1.10 IV, then HSV 1 gG-specific IgG, CSF and HSV 2 gG-specific IgG, CSF will be added
Not recommended for HSV testing; IgM lacks adequate predictive value for acute infection
Molecular testing is preferred
Semi-Quantitative Enzyme-Linked Immunosorbent Assay
Not recommended as a stand-alone test; refer to HSV antibody reflex test
Semi-Quantitative Chemiluminescent Immunoassay
Not recommended for HSV testing; IgM lacks adequate predictive value for acute infection
If pursuing antibody testing, refer to HSV IgG glycoprotein types 1 and 2 antibodies
If acute HSV infection is suspected, molecular testing is preferred; refer to HSV by PCR
Semi-Quantitative Enzyme-Linked Immunosorbent Assay
Not recommended for diagnosing congenital infections in newborns; tests should be selected individually to target the most likely infectious agents
May be used in pregnant women to assess past exposure or immunization to toxoplasma, rubella, cytomegalovirus (CMV), and HSV
Semi-Quantitative Chemiluminescent Immunoassay
Panel includes cytomegalovirus antibody, IgG; HSV type 1 (HSV-1) and HSV type 2 (HSV-2) antibodies, IgG; rubella antibody, IgG; and Toxoplasma gondii antibody, IgG
Not recommended for diagnosing congenital infections in newborns; tests should be selected individually to target the most likely infectious agents
Panel includes cytomegalovirus antibody, IgM; HSV-1 and HSV-2 antibodies, IgM; rubella antibody, IgM; and Toxoplasma gondii antibody, IgM
Semi-Quantitative Chemiluminescent Immunoassay/Semi-Quantitative Enzyme-Linked Immunosorbent Assay
Molecular testing is preferred for patients presenting with meningitis/encephalitis; refer to PCR panel for meningitis/encephalitis
Semi-Quantitative Enzyme-Linked Immunosorbent Assay/Semi-Quantitative Chemiluminescent Immunoassay
Reflex pattern: if HSV 1 and/or 2 IgG, CSF is 1.10 IV or greater, then HSV 1 G-specific IgG, CSF and HSV 2 G-specific IgG, CSF will be added
Not a preferred test; refer to relevant test for the specific pathogen suspected
Semi-Quantitative Enzyme-Linked Immunosorbent Assay/Semi-Quantitative Chemiluminescent Immunoassay
Reflex pattern: if HSV 1 and/or 2 IgG is 1.10 IV or greater, then HSV 1 G-specific IgG and HSV 2 G-specific IgG will be added
For best results, specify specimen source and suspected virus on order form; molecular diagnostics are preferred for suspected invasive CMV
Cell Culture/Immunofluorescence
Generally, virus-specific testing (eg, antigen detection or molecular) is recommended
Cell Culture
Molecular diagnostics are preferred for suspected invasive CMV
Cell Culture/Immunofluorescence
Medical Experts
Couturier

Hillyard

Schlaberg

References
Choosing Wisely - Retest Interval - American Academy of Family Physicians - 20 Things
American Academy of Family Physicians. Choosing Wisely. Twenty Things Physicians and Patients Should Question. American Board of Internal Medicine (ABIM) Foundation. [Updated: Aug 2018; Accessed: May 2019]
19348670
Anzivino E, Fioriti D, Mischitelli M , et al. Herpes simplex virus infection in pregnancy and in neonate: status of art of epidemiology, diagnosis, therapy and prevention. Virol J. 2009;6:40.
CDC - 2015 Sexually Transmitted Diseases Treatment Guidelines - Special Populations
Workowski KA, Bolan GA. Sexually transmitted diseases treatment guidelines, 2015. U.S. Department of Health and Human Services, Centers for Disease Control and Prevention. Morbidity and Mortality Weekly Report. [Posted: Jun 2015; Accessed: Feb 2020]
19797284
17939933
18156035
23359576
17317423
25677998
Neu N, Duchon J, Zachariah P. TORCH infections. Clin Perinatol. 2015;42(1):77-103.
Reflex pattern: if HSV by polymerase chain reaction (PCR) result is detected, subtyping will be added