herpes%20simplex%20virus%20infection
HERPES SIMPLEX VIRUS INFECTION
Primary herpes simplex virus (HSV) infection is first infection with either herpes simplex virus-1 (HSV-1) or herpes simplex virus-2 (HSV-2) in individuals who do not have antibodies to either HSV-1 or HSV-2.
First episode-non primary infection is infection with either HSV-1 or HSV-2 in individuals who have previously existing antibodies against HSV-1 or HSV-2 respectively.
Recurrent HSV infection results from reactivation of latent virus. It is usually brought about by triggering factors eg UV light, immunosuppression.
Orolabial HSV disease is mostly caused by HSV-1 that occurs most commonly in children <5 years of age. It is transmitted through close contact with individuals who have active viral shedding.
Genital HSV disease is caused by HSV-2 that is the usual cause of herpes genitalis. It typically occurs in adults and transmitted through sexual contact.

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

Classification

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

Laboratory Tests

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
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