Herpes%20simplex%20virus%20infection Diagnosis

• Diagnosis is usually based on distinctive lesions but lab tests may be done if lesions are atypical & 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 w/ HSV-1 infection than HSV-2
• Occurs most commonly in children <5 years; transmitted through close contact w/ individuals who have active viral shedding
• May be asymptomatic
• Painful vesicles & 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 & 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 & 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 & 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
• Local symptoms: Pain, itching, dysuria, vaginal & urethral discharge & 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, & presents w/ lymphadenopathy & systemic symptoms
• More severe infections & higher rate of complications in women:
  
  • Lesions occur on vulva, cervix, vagina, clitoris, urethral or perianal skin & 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 & superinfection w/ bacteria or fungi
• Infection in men:
  •  Lesions usually occur on the prepuce, glans penis, penile shaft; usually w/ 6-10 vesicles
  •  Perianal infection & 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 herpes simplex virus (HSV) replication
  • Test of choice because it is rapid (within 7 days), sensitive & allows discrimination between HSV-1 & HSV-2

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

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

Tzanck Smear

• A Tzanck preparation (Wright-Giemsa 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