Herpes%20simplex%20virus%20infection Diagnosis

• Diagnosis is usually based on distinctive lesions but lab tests may be done if lesions are atypical and if patient has a central nervous system (CNS) disease or severe infection or is pregnant, immunocompromised, or a neonate

Orolabial Herpes Simplex Virus (HSV) Disease

• Most orolabial lesions are caused by HSV-1 but may also be caused by HSV-2
  
  • Recurrent disease tends to occur more frequently with HSV-1 infection than HSV-2
• Occurs most commonly in children <5 years; transmitted through close contact with individuals who have active viral shedding
• May be asymptomatic
• Painful vesicles and ulcerative lesions on tongue palate, gingiva, buccal mucosa or lips
• 3-5 lesions typically appear at the vermilion border of the lips (cold sores)
  
  • Lesions become pustular, ulcerative and crusted within 72-96 hours; pain resolves soon after that
• Edema of oropharynx causes difficulty in swallowing (sore throat)
• Halitosis
• Drooling which may bring about lesions in the chin and neck
• Cervical lymphadenopathy
• Systemic symptoms: Fever, myalgia, malaise, flu-like symptoms
• Disease duration: 2-3 weeks

Genital Herpes Simplex Virus (HSV) Disease

• HSV-2 is usually the cause of herpes genitalis but HSV-1 may occur in up to ¹/₃ of new cases
  
  • HSV-1 tends to cause fewer recurrences and milder disease than HSV-2
• Typically occurs in adults; usually transmitted through sexual contact
  • Incubation period is 2 days-2 weeks after exposure; primary lesions appear 4-7 days after contact
• Initially, most infections may be asymptomatic or atypical, thus often undiagnosed
  • Atypical presentations include small erosions or fissures and urethritis or dysuria without lesions
• Local symptoms: Pain, itching, dysuria, vaginal and urethral discharge and tender inguinal lymphadenopathy
• Systemic symptoms: Fever, headache, myalgia, abdominal pain
• Lesions may be present in varying stages (vesicles, pustules or ulcers)
• Primary genital infection is different from recurrent infection in that it is often more painful, extensive, prolonged, likely to be bilateral, and presents with lymphadenopathy and systemic symptoms
• More severe infections and higher rate of complications in women:
  
  • Lesions occur on vulva, cervix, vagina, clitoris, urethral or perianal skin and extragenital areas eg buttocks, thighs or perineum
  • Painful lesions contain a large amount of infectious viral particles which are excreted over 3 weeks
  • Systemic complications: Urinary retention syndrome, aseptic meningitis, transverse myelitis, sacral radiculopathy, extragenital lesions (buttocks, perineum or thighs), disseminated infections and superinfection with bacteria or fungi
• Infection in men:
  •  Lesions usually occur on the prepuce, glans penis, penile shaft; usually with 6-10 vesicles
  •  Perianal infection and proctitis may be common in homosexual men
  •  Systemic complications rarely occur in men; aseptic meningitis is reported
  •  Extragenital areas eg buttocks, perineum or thighs may be affected
•  Disease duration: 2-4 weeks

Virologic Tests

• Viral culture
  
  • Sources of specimens for culture: Skin, mucocutaneous lesions, blood, cerebrospinal fluid (CSF), urine, stool, oropharynx or conjunctiva
  • A positive viral culture will show cytopathic effect characteristic of HSV replication
  • Test of choice because it is rapid (within 7 days), sensitive and allows discrimination between HSV-1 and HSV-2
    • Low sensitivity in recurrent and healing lesions

• Antigen detection tests
  
  • Eg immunoperoxidase tests, immunofluorescence, enzyme immunoassay
  • Detect HSV antigens
  • Rapid but do not allow discrimination between HSV-1 and HSV-2

• Polymerase chain reactions (PCR)
  • Test for HSV DNA
  • Highly sensitive, but its role as a diagnostic test for cutaneous HSV is not well-defined
  • Test of choice for HSV infection in the central nervous system (CNS) and systemic infections
  • Nucleic acid amplification tests (NAAT)
    • Most sensitive test to detect HSV from genital ulcers or other mucocutaneous lesions

Type-specific Serologic Tests

• Eg enzyme-linked immunosorbent assay (ELISA), complement fixation tests, Western blot
• Do not distinguish anogenital from orolabial infection
• Immunoglobulin G (IgG) antibody indicates past infection while immunoglobulin M (IgM) antibody suggests recent infection
  • IgM antibody detection lacks sensitivity especially for recurrent infections
• May be used to diagnosed HSV infection in the absence of genital lesions
• Useful in identification and a guide for counseling of pregnant women at risk for HSV-2 infection

Tzanck Smear

• A Tzanck preparation (Wright-Giemsa or Papanicolaou stain) may show multinucleated giant cells or intranuclear inclusions from the scrapings from the base of freshly ruptured lesions
• The method cannot reliably differentiate HSV from varicella-zoster virus (VZV)